4,984 results on '"Barman, P."'
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2. Effect of Direct Sowing and Stratification on Germination and Growth of Peach under Sub-tropical Climate of Uttar Pradesh
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Srivastava, K.K., Barman, P., and Kumar, D.
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- 2021
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3. Reconfigurable Spin-Wave Properties in Two-Dimensional Magnonic Crystals Formed of Diamond and Triangular Shaped Nanomagnets
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Barman, Swapnil and Mitra, Rajib Kumar
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Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Two-dimensional ferromagnetic nanodot structures exhibit intriguing magnetization dynamics and hold promise for future magnonic devices. In this study, we present a comparative experimental investigation into the reconfigurable magnetization dynamics of non-ellipsoidal diamond and triangular-shaped nanodot structures, employing broadband ferromagnetic resonance spectroscopy. Our findings reveal substantial variations in the spin wave (SW) spectra of these structures under different bias field strengths (H) and angles ({\phi}). Notably, the diamond nanodot structure exhibits a variation from nearly symmetric W-shaped dispersion to a skewed dispersion and subsequent transition to a discontinuous dispersion with subtle variation in bias field angle. On the other hand, in the triangular nanodot array a SW mode anti-crossing appears at {\phi} = 15{\deg} which is starkly modified with the increase in {\phi} to 30{\deg}. By analyzing the static magnetic configurations, we unveil the nature of the SW spectra in these two shapes. We reinforce our observations with simulated spatial power and phase maps. This study underscores the critical impact of dot shape and inversion symmetry on SW dynamical response, highlighting the significance of selecting appropriate structures and bias field strength and orientation for required functionalities. The remarkable tunability demonstrated by the magnonic crystals underscores their potential suitability for future magnonic devices.
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- 2024
4. Deciphering Assamese Vowel Harmony with Featural InfoWaveGAN
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Barman, Sneha Ray, Mahanta, Shakuntala, and Sharma, Neeraj Kumar
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Computer Science - Computation and Language - Abstract
Traditional approaches for understanding phonological learning have predominantly relied on curated text data. Although insightful, such approaches limit the knowledge captured in textual representations of the spoken language. To overcome this limitation, we investigate the potential of the Featural InfoWaveGAN model to learn iterative long-distance vowel harmony using raw speech data. We focus on Assamese, a language known for its phonologically regressive and word-bound vowel harmony. We demonstrate that the model is adept at grasping the intricacies of Assamese phonotactics, particularly iterative long-distance harmony with regressive directionality. It also produced non-iterative illicit forms resembling speech errors during human language acquisition. Our statistical analysis reveals a preference for a specific [+high,+ATR] vowel as a trigger across novel items, indicative of feature learning. More data and control could improve model proficiency, contrasting the universality of learning., Comment: to be included in the Interspeech Proceedings
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- 2024
5. Dark matter-electron scattering and freeze-in scenarios in the light of $Z^\prime$ mediation
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Barman, Basabendu, Das, Arindam, and Mandal, Sanjoy
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We investigate dark matter (DM)-electron scattering in a minimal $U(1)_X$ extension of the Standard Model (SM), where the DM can appear as a Majorana fermion, a complex singlet scalar or a Dirac fermion. To study bounds on the $U(1)_X$ gauge coupling $(g_X)$ and new gauge boson mass $(M_{Z^\prime})$, from DM-electron scattering, we consider several direct search experiments like CDMS, DAMIC, SENSEI, PandaX-II, DarkSide-50 and XENON1T-S2 for different $U(1)_X$ charges. In this set-up we consider DM production via freeze-in both in radiation dominated and modified cosmological background to project sensitivities on $g_X-M_{Z^\prime}$ plane satisfying observed relic abundance. DM-electron scattering could provide comparable, or even stronger bounds than those obtained from the electron/ muon $(g-2)$, low energy scattering and intensity frontier experiments within 0.01 GeV $\lesssim M_{Z^\prime} \lesssim$ 0.1 GeV. Constrains from freeze-in could provide stronger sensitivities for $M_{Z^\prime}\gtrsim \mathcal{O}(1)$ GeV, however, these limits are comparable to those obtained from LHCb, LEP experiments for $\mathcal{O}(10)$ GeV $\lesssim M_{Z^\prime} \lesssim 150$ GeV. In future, electron-muon scattering (MUonE), proton (FASER, DUNE) and electron/positron (ILC) beam dump experiments could probe these parameters., Comment: 22 pages, 6 figures
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- 2024
6. Top-philic Machine Learning
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Barman, Rahool Kumar and Biswas, Sumit
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High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
In this article, we review the application of modern machine-learning (ML) techniques to boost the search for processes involving the top quarks at the LHC. We revisit the formalism of Convolutional Neural Networks (CNNs), Graph Neural Networks (GNNs), and Attention Mechanisms. Based on recent studies, we explore their applications in designing improved top taggers, top reconstruction, and event classification tasks. We also examine the ML-based likelihood-free inference approach and generative unfolding models, focusing on their applications to scenarios involving top quarks., Comment: A short review prepared by invitation for EPJ Special Topics issue. Version accepted for publication; 45 pages, 17 figures, 1 table; v2: typos corrected
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- 2024
7. DIDChain: Advancing Supply Chain Data Management with Decentralized Identifiers and Blockchain
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Herbke, Patrick, Lamichhane, Sid, Barman, Kaustabh, Pandey, Sanjeet Raj, Küpper, Axel, Abraham, Andreas, and Sabadello, Markus
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Computer Science - Cryptography and Security ,Computer Science - Networking and Internet Architecture - Abstract
Supply chain data management faces challenges in traceability, transparency, and trust. These issues stem from data silos and communication barriers. This research introduces DIDChain, a framework leveraging blockchain technology, Decentralized Identifiers, and the InterPlanetary File System. DIDChain improves supply chain data management. To address privacy concerns, DIDChain employs a hybrid blockchain architecture that combines public blockchain transparency with the control of private systems. Our hybrid approach preserves the authenticity and reliability of supply chain events. It also respects the data privacy requirements of the participants in the supply chain. Central to DIDChain is the cheqd infrastructure. The cheqd infrastructure enables digital tracing of asset events, such as an asset moving from the milk-producing dairy farm to the cheese manufacturer. In this research, assets are raw materials and products. The cheqd infrastructure ensures the traceability and reliability of assets in the management of supply chain data. Our contribution to blockchain-enabled supply chain systems demonstrates the robustness of DIDChain. Integrating blockchain technology through DIDChain offers a solution to data silos and communication barriers. With DIDChain, we propose a framework to transform the supply chain infrastructure across industries., Comment: Accepted to be published at the 18th IEEE International Conference on Service-Oriented System Engineering 2024
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- 2024
8. Lepton Collider as a window to Reheating
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Barman, Basabendu, Bhattacharya, Subhaditya, Jahedi, Sahabub, Pradhan, Dipankar, and Sarkar, Abhik
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics ,High Energy Physics - Theory - Abstract
We propose a search strategy for MeV-scale feebly interacting massive particle (FIMP) dark matter (DM) at the $e^+e^-$ collider. We argue, detection of a mono-$\gamma$ signal plus missing energy can indicate to an MeV-scale reheating temperature of the Universe, after addressing observed DM abundance and other relevant constraints., Comment: 9 pages, 7 figures, and 1 table
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- 2024
9. Signatures of gravitational wave memory in the radiative process of entangled quantum probes
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Barman, Subhajit, Chakraborty, Indranil, and Mukherjee, Sajal
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General Relativity and Quantum Cosmology ,High Energy Physics - Theory ,Quantum Physics - Abstract
In this article, we examine entangled quantum probes in geodesic trajectories in a background with gravitational wave (GW) burst. In particular, these quantum probes are prepared initially either in the symmetric or anti-symmetric Bell's states and we study the radiative process as the GW burst passes. Our considered GW burst backgrounds have the profiles of -- Heaviside-theta, $tanh$, Gaussian, and $sech$-squared functions respectively. The first two burst profiles have an asymmetric nature and thus result in non-zero gravitational wave memory. Whereas, for the last two symmetric profiles there is no asymptotic memory. For eternal switching, our observations suggest that the collective transition rate for the entangled probes due to symmetric GW bursts remains the same as obtained in the flat space. Whereas, for asymmetric bursts with memory, there is a finite change, indicating a direct possibility to distinguish between the two above-mentioned scenarios. We also consider finite switching in terms of Gaussian functions and observe characteristic differences in the radiative process between the GW backgrounds with and without memory. Notably, if the Gaussian switching is peaked much later compared to the passing of GW, only memory profiles contribute to the radiative process. We further discuss the physical implications of our findings., Comment: 22 pages, 5 figures, comments are welcome
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- 2024
10. Causal Contextual Bandits with Adaptive Context
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Madhavan, Rahul, Maiti, Aurghya, Sinha, Gaurav, and Barman, Siddharth
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Computer Science - Machine Learning ,Computer Science - Artificial Intelligence - Abstract
We study a variant of causal contextual bandits where the context is chosen based on an initial intervention chosen by the learner. At the beginning of each round, the learner selects an initial action, depending on which a stochastic context is revealed by the environment. Following this, the learner then selects a final action and receives a reward. Given $T$ rounds of interactions with the environment, the objective of the learner is to learn a policy (of selecting the initial and the final action) with maximum expected reward. In this paper we study the specific situation where every action corresponds to intervening on a node in some known causal graph. We extend prior work from the deterministic context setting to obtain simple regret minimization guarantees. This is achieved through an instance-dependent causal parameter, $\lambda$, which characterizes our upper bound. Furthermore, we prove that our simple regret is essentially tight for a large class of instances. A key feature of our work is that we use convex optimization to address the bandit exploration problem. We also conduct experiments to validate our theoretical results, and release our code at our project GitHub repository: https://github.com/adaptiveContextualCausalBandits/aCCB., Comment: Reinforcement Learning Conference (RLC) 2024, 10 pages (31 pages including appendix), 8 plots. arXiv admin note: text overlap with arXiv:2111.00886
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- 2024
11. Gravitational wave signatures of cogenesis from a burdened PBH
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Barman, Basabendu, Haque, Md Riajul, and Zapata, Óscar
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Astrophysics - Cosmology and Nongalactic Astrophysics ,High Energy Physics - Phenomenology - Abstract
We explore the possibility of explaining the observed dark matter (DM) relic abundance, along with matter-antimatter asymmetry, entirely from the evaporation of primordial black holes (PBH), beyond the semi-classical approximation. We find that, depending on the timing of modification to the semi-classical approximation and the efficiency of the backreaction, it is possible to produce the correct DM abundance for PBHs with masses $\gtrsim\mathcal{O}(10^3)$ g, whereas producing the right amount of baryon asymmetry requires light PBHs with masses $\lesssim\mathcal{O}(10^2)$ g, satisfying bounds on the PBH mass from the Cosmic Microwave Background and Big Bang Nucleosynthesis. However, in a simplistic scenario, achieving both {\it simultaneously} is not feasible, typically because of the stringent Lyman-$\alpha$ constraint on warm dark matter mass. We also demonstrate how induced gravitational waves from PBH density fluctuations can provide a window to test the memory-burden effects, thereby placing constraints on either the DM mass scale or the scale of leptogenesis., Comment: 27 pages, 8 figures
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- 2024
12. Dominating surface-group representations via Fock-Goncharov coordinates
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Barman, Pabitra and Gupta, Subhojoy
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Mathematics - Geometric Topology - Abstract
Let $S$ be a punctured surface of negative Euler characteristic. We show that given a generic representation $\rho:\pi_1(S) \rightarrow \mathrm{PSL}_n(\mathbb{C})$, there exists a positive representation $\rho_0:\pi_1(S) \rightarrow \mathrm{PSL}_n(\mathbb{R})$ that dominates $\rho$ in the Hilbert length spectrum as well as in the translation length spectrum, for the translation length in the symmetric space $\mathbb{X}_n= \mathrm{PSL}_n(\mathbb{C})/\mathrm{PSU}(n)$. Moreover, the $\rho_0$-lengths of peripheral curves remain unchanged. The dominating representation $\rho_0$ is explicitly described via Fock-Goncharov coordinates. Our methods are linear-algebraic, and involve weight matrices of weighted planar networks., Comment: 39 pages
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- 2024
13. Diffusion of brightened dark excitons in a high-angle incommensurate Moir\'e homobilayer
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Ray, Arnab Barman, Ollis, Trevor, R., Sethuraj K., and Vamivakas, Anthony Nickolas
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Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
The last few years have witnessed a surge in interest and research efforts in the field of twistronics, especially in low-angle twisted bilayers of transition metal dichalocogenides. These novel material platforms have been demonstrated to host periodic arrays of excitonic quantum emitters, interlayer excitons with long lifetimes, and exotic many-body states. While much remains to be known and understood about these heterostructures, the field of high-angle, incommensurate bilayers is even less explored. At twist angles larger than a few degrees, the presence of periodicity in these bilayers becomes chaotic, making the systems essentially aperiodic and incommensurate in nature due to the limitations of fabrication techniques. In this work, we demonstrate the emergence of a brightened dark intralayer exciton in twisted molybdenum diselenide homobilayer. We show that this dark exciton diffuses across the excitation spot more efficiently as compared to trions or excitons, reaching diffusion lengths greater than 4 microns. Temperature-dependent spectra provide corroborative evidence and reveal a brightened dark trion. Our results reveal some of the richness of the physics of these high-angle systems.
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- 2024
14. Kramers nodal line in the charge density wave state of YTe$_3$ and the influence of twin domains
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Sarkar, Shuvam, Bhattacharya, Joydipto, Bhakuni, Pramod, Sadhukhan, Pampa, Batabyal, Rajib, Malliakas, Christos D., Bianchi, Marco, Curcio, Davide, Roy, Shubhankar, Pariari, Arnab, Sathe, Vasant G., Mandal, Prabhat, Kanatzidis, Mercouri G., Hofmann, Philip, Chakrabarti, Aparna, and Barman, Sudipta Roy
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Condensed Matter - Materials Science - Abstract
Recent studies have focused on the relationship between charge density wave (CDW) collective electronic ground states and nontrivial topological states. Using angle-resolved photoemission and density functional theory, we establish that YTe$_3$ is a CDW-induced Kramers nodal line (KNL) metal, a newly proposed topological state of matter. YTe$_3$ is a non-magnetic quasi-2D chalcogenide with a CDW wave vector ($q_{\rm cdw}$) of 0.2907c$^*$. Scanning tunneling microscopy and low energy electron diffraction revealed two orthogonal CDW domains, each with a unidirectional CDW and similar YTe$_3$. The effective band structure (EBS) computations, using DFT-calculated folded bands, show excellent agreement with ARPES because a realistic x-ray crystal structure and twin domains are considered in the calculations. The Fermi surface and ARPES intensity plots show weak shadow bands displaced by $q_{\rm cdw}$ from the main bands. These are linked to CDW modulation, as the EBS calculation confirms. Bilayer split main and shadow bands suggest the existence of crossings, according to theory and experiment. DFT bands, including spin-orbit coupling, indicate a nodal line along the $\Sigma$ line from multiple band crossings perpendicular to the KNL. Additionally, doubly degenerate bands are only found along the KNL at all energies, with some bands dispersing through the Fermi level.
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- 2024
15. Probing Reheating with Gravitational Waves from Graviton Bremsstrahlung
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Barman, Basabendu, Bernal, Nicolás, Cléry, Simon, Mambrini, Yann, Xu, Yong, and Zapata, Óscar
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Astrophysics - Cosmology and Nongalactic Astrophysics ,High Energy Physics - Phenomenology - Abstract
In this talk, based on arXiv:2301.11345, arXiv:2305.16388, arXiv:2311.12694, we discuss the production of primordial gravitational waves (GW) sourced by graviton bremsstrahlung during inflationary reheating. For reheating, we consider inflaton decays and annihilations into pairs of bosons or fermions, assuming an inflaton $\phi$ that oscillates around a generic monomial potential $V(\phi) \propto \phi^n$. The GW spectrum exhibits distinct features depending on the underlying reheating dynamics, which is controlled by the inflaton potential and the type of coupling between the inflaton and the matter fields. We show that the produced stochastic GW background could be probed in next-generation GW detectors, especially at high frequencies. We further highlight the potential of bremsstrahlung-induced GW to probe the underlying dynamics of reheating., Comment: 6 pages, 4 figures. Contribution to the 2024 Electroweak session of the 58th Rencontres de Moriond. Based on Refs. arXiv:2301.11345, arXiv:2305.16388 and arXiv:2311.12694
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- 2024
16. Mirror-enhanced acceleration induced geometric phase: towards detection of Unruh effect
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Barman, Dipankar, Ghosh, Debasish, and Majhi, Bibhas Ranjan
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Quantum Physics ,General Relativity and Quantum Cosmology ,High Energy Physics - Theory - Abstract
Fulling-Davies-Unruh effect contains great amount of theoretical importance in various branches of physics. Requirement of very high acceleration hinders its experimental evidence. We propose a novel model to capture this effect experimentally through measuring the Pancharatnam-Berry phase (PBP) of the accelerated quantum system. We find that allowing the qubit's motion along one of the parallel directions of two parallel mirrors and by keeping it in between them, PBP can be greatly enhanced. Our investigation shows that for the current measurable PBP ($\sim 10^{-6}$ rad), energy gap $\sim1$ GHz of the qubit, distance between two mirrors $L\sim150$ (or $300)\,m$ and detector's position $z_0 \sim3.3\,m$ the required acceleration of the qubit can be as low as $a\sim 10^9~ m/s^2$. This value is potentially very achievable within the current technology and thereby providing a very close to realistic model for experimentally verify the aforesaid quantum phenomenon., Comment: Latex, 5 pages, 3 figures
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- 2024
17. Anomalous Inverse Spin Hall Effect (AISHE) due to Unconventional Spin Currents in Ferromagnetic Films with Tailored Interfacial Magnetic Anisotropy
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Aon, Soumik, Bhunia, Harekrishna, Pal, Pratap Kumar, Miah, Abu Bakkar, Mahapatra, Dhananjaya, Barman, Anjan, and Mitra, Partha
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Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
A single layer ferromagnetic film magnetized in the plane of an ac current flow, exhibits a characteristic Hall voltage with harmonic and second harmonic components, which is attributed to the presence of spin currents with polarization non-collinear with the magnetization. A set of 30 nm thick permalloy (Py) films used in this study are deposited at an oblique angle with respect to the substrate plane which induces an in-plane easy axis in the magnetization of the initial nucleating layers of the films which is distinct from the overall bulk magnetic properties of the film. This unusual magnetic texture provides a platform for the direct detection of inverse spin Hall effect in Hall bar shaped macroscopic devices at room temperatures which we denote as Anomalous Inverse Spin Hall Effect (AISHE). Control samples fabricated by normal deposition of permalloy with slow rotation of substrate shows significant reduction of the harmonic Hall signal that further substantiates the model. The analysis of the second harmonic Hall signal corroborates the presence of spin-orbit torque arising from the unconventional spin-currents in the single-layer ferromagnets.
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- 2024
18. Long-Term Effects of the Dana Center Math Pathways Model: Evidence from a Randomized Trial. A CAPR Working Paper
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Columbia University, Center for the Analysis of Postsecondary Readiness (CAPR), Columbia University, Community College Research Center (CCRC), MDRC, Sepanik, Susan, and Barman, Sukanya
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Following up on an individual-level randomized controlled trial of a Dana Center Math Pathways (DCMP) model, this study assessed longer-term impacts on students' math completion, academic progress, and academic attainment. The version of the DCMP that was assessed in this study diversified the developmental and college-level math course content that students take, separating it into distinct pathways that better aligned with their career interests. It also streamlined developmental math sequences into a one-semester developmental course for all students, regardless of placement level, and implemented evidence-based curricula and pedagogy to engage students in active problem solving that was pertinent to real-life situations. The study, which followed 1,411 students from four Texas community colleges and ten campuses, found that, in the five years after random assignment, program group students were consistently more likely to successfully complete their first college-level math courses than control group students. The study did not find impacts after five years on the number of overall college credits that students accrued or on the likelihood that students attained a credential or transferred to a four-year college.
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- 2023
19. Intrinsic and extrinsic plasmons in the hard x-ray photoelectron spectra of nearly free electron metals
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Balal, Mohammad, Sarkar, Shuvam, Bhakuni, Pramod, Gloskovskii, Andrei, Chakrabarti, Aparna, and Barman, Sudipta Roy
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Condensed Matter - Materials Science - Abstract
Collective plasmon excitations in solids that result from the process of photoemission are an important area of fundamental research. In this study, we identify a significant number ($n$) of multiple bulk plasmons ($n\omega_p$) in the hard x-ray photoelectron spectra of the core levels and valence bands (VBs) of two well-known, nearly free electron metals, aluminum (Al) and magnesium (Mg). On the basis of earlier theoretical works, we estimate the contributions of extrinsic, intrinsic, and interference processes to the intensities of 1$s$ to 2$s$ core level plasmons. The intrinsic contribution diminishes from 22% for 1$\omega_p$, to 4.4% for 2$\omega_p$, and becomes negligible thereafter (0.5% for 3$\omega_p$). The extrinsic and intrinsic plasmon contributions do not vary significantly across a broad range of photoelectron kinetic energies, and also between the two metals (Al and Mg). The interference contribution varies from negative to zero as $n$ increases. An asymmetric line shape is observed for the bulk plasmons, which is most pronounced for 1$\omega_p$. Signature of the surface plasmon is detected in normal emission, and it exhibits a significantly increased intensity in the grazing emission. The VB spectra of Al and Mg, which are dominated by $s$-like states, exhibit excellent agreement with the calculated VB based on density functional theory. The VB exhibits four multiple bulk plasmon peaks in the loss region, which are influenced by an intrinsic process in addition to the extrinsic process. On a completely oxidized aluminum surface, the relative intensity of the Al metal bulk plasmon remains nearly unaltered, while the surface plasmon is completely attenuated., Comment: Phys. Rev. B (in press)
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- 2024
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20. AIS 2024 Challenge on Video Quality Assessment of User-Generated Content: Methods and Results
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Conde, Marcos V., Zadtootaghaj, Saman, Barman, Nabajeet, Timofte, Radu, He, Chenlong, Zheng, Qi, Zhu, Ruoxi, Tu, Zhengzhong, Wang, Haiqiang, Chen, Xiangguang, Meng, Wenhui, Pan, Xiang, Shi, Huiying, Zhu, Han, Xu, Xiaozhong, Sun, Lei, Chen, Zhenzhong, Liu, Shan, Zhang, Zicheng, Wu, Haoning, Zhou, Yingjie, Li, Chunyi, Liu, Xiaohong, Lin, Weisi, Zhai, Guangtao, Sun, Wei, Cao, Yuqin, Jiang, Yanwei, Jia, Jun, Zhang, Zhichao, Chen, Zijian, Zhang, Weixia, Min, Xiongkuo, Göring, Steve, Qi, Zihao, and Feng, Chen
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Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Multimedia - Abstract
This paper reviews the AIS 2024 Video Quality Assessment (VQA) Challenge, focused on User-Generated Content (UGC). The aim of this challenge is to gather deep learning-based methods capable of estimating the perceptual quality of UGC videos. The user-generated videos from the YouTube UGC Dataset include diverse content (sports, games, lyrics, anime, etc.), quality and resolutions. The proposed methods must process 30 FHD frames under 1 second. In the challenge, a total of 102 participants registered, and 15 submitted code and models. The performance of the top-5 submissions is reviewed and provided here as a survey of diverse deep models for efficient video quality assessment of user-generated content., Comment: CVPR 2024 Workshop -- AI for Streaming (AIS) Video Quality Assessment Challenge
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- 2024
21. Resonant Reheating
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Barman, Basabendu, Bernal, Nicolás, and Xu, Yong
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High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
We investigate a novel reheating scenario proceeding through $s$-channel inflaton annihilation, mediated by a massive scalar. If the inflaton $\phi$ oscillates around the minimum of a monomial potential $\propto \phi^{n}$, we reveal the emergence of resonance phenomena originating from the dynamic evolution of the inflaton mass for $n>2$. Consequently, a resonance appears in both the radiation and the temperature evolution during the reheating process. By solving the coupled Boltzmann equations, we present solutions for radiation and temperature. We find non-trivial temperature characteristics during reheating, depending on the value of $n$ and the masses of the inflaton and mediator. Some phenomenological aspects of the model are explored. As a concrete example, we show that the same mediator participates in the genesis of dark matter, modifying the standard freeze-in dynamics. In addition, we demonstrate that the resonant reheating scenario could be tested by next-generation low- and high-frequency gravitational wave detectors., Comment: 28 pages, 11 figures
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- 2024
22. Hook length biases in ordinary and $t$-regular partitions
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Singh, Gurinder and Barman, Rupam
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Mathematics - Combinatorics ,Mathematics - Number Theory - Abstract
In this article, we study hook lengths of ordinary partitions and $t$-regular partitions. We establish hook length biases for the ordinary partitions and motivated by them we find a few interesting hook length biases in $2$-regular partitions. For a positive integer $k$, let $p_{(k)}(n)$ denote the number of hooks of length $k$ in all the partitions of $n$. We prove that $p_{(k)}(n)\geq p_{(k+1)}(n)$ for all $n\geq0$ and $n\ne k+1$; and $p_{(k)}(k+1)- p_{(k+1)}(k+1)=-1$ for $k\geq 2$. For integers $t\geq2$ and $k\geq1$, let $b_{t,k}(n)$ denote the number of hooks of length $k$ in all the $t$-regular partitions of $n$. We find generating functions of $b_{t,k}(n)$ for certain values of $t$ and $k$. Exploring hook length biases for $b_{t,k}(n)$, we observe that in certain cases biases are opposite to the biases for ordinary partitions. We prove that $b_{2,2}(n)\geq b_{2,1}(n)$ for all $n>4$, whereas $b_{2,2}(n)\geq b_{2,3}(n)$ for all $n\geq 0$. We also propose some conjectures on biases among $b_{t,k}(n)$., Comment: To appear at Journal of Number Theory
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- 2024
23. Time-resolved Hubble Space Telescope Wide Field Camera 3 Spectrophotometry Reveals Inefficient Day-to-Night Heat Redistribution in the Highly Irradiated Brown Dwarf SDSS 1557B
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Amaro, Rachael C., Apai, Daniel, Lew, Ben W. P., Zhou, Yifan, Lothringer, Joshua D., Casewell, Sarah L., Tan, Xianyu, Barman, Travis, Marley, Mark S., Mayorga, L. C., and Parmentier, Vivien
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Astrophysics - Earth and Planetary Astrophysics ,Astrophysics - Solar and Stellar Astrophysics - Abstract
Brown dwarfs in ultra-short period orbits around white dwarfs offer a unique opportunity to study the properties of tidally-locked, fast rotating (1-3 hr), and highly-irradiated atmospheres. Here, we present phase-resolved spectrophotometry of the white dwarf-brown dwarf (WD-BD) binary SDSS 1557, which is the fifth WD-BD binary in our six-object sample. Using the Hubble Space Telescope Wide Field Camera 3 Near-infrared G141 instrument, the 1.1 to 1.7 $\mu$m phase curves show rotational modulations with semi-amplitudes of 10.5$\pm$0.1%. We observe a wavelength dependent amplitude, with longer wavelengths producing larger amplitudes, while no wavelength dependent phase shifts were identified. The phase-resolved extracted BD spectra exhibit steep slopes and are nearly featureless. A simple radiative energy redistribution atmospheric model recreates the hemisphere integrated brightness temperatures at three distinct phases and finds evidence for weak redistribution efficiency. Our model also predicts a higher inclination than previously published. We find that SDSS 1557B, the second most irradiated BD in our sample, is likely dominated by clouds on the night side, whereas the featureless day side spectrum is likely dominated by H$^-$ opacity and a temperature inversion, much like the other highly-irradiated BD EPIC2122B., Comment: 19 pages and 11 figures. Accepted to Astrophysical Journal
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- 2024
24. Orbital and Atmospheric Characterization of the 1RXS J034231.8+121622 System Using High-Resolution Spectroscopy Confirms That The Companion is a Low-Mass Star
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Ó, Clarissa R. Do, Sappey, Ben, Konopacky, Quinn M., Ruffio, Jean-Baptiste, O'Neil, Kelly K., Do, Tuan, Martinez, Gregory, Barman, Travis S., Nguyen, Jayke S., Xuan, Jerry W., Theissen, Christopher A., Blunt, Sarah, Thompson, William, Hsu, Chih-Chun, Baker, Ashley, Bartos, Randall, Blake, Geoffrey A., Calvin, Benjamin, Cetre, Sylvain, Delorme, Jacques-Robert, Doppmann, Greg, Echeverri, Daniel, Finnerty, Luke, Fitzgerald, Michael P., Inglis, Julie, Jovanovic, Nemanja, López, Ronald A., Mawet, Dimitri, Morris, Evan, Pezzato, Jacklyn, Schofield, Tobias, Skemer, Andrew, Wallace, J. Kent, Wang, Jason J., Wang, Ji, and Liberman, Joshua
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Astrophysics - Solar and Stellar Astrophysics ,Astrophysics - Earth and Planetary Astrophysics - Abstract
The 1RXS J034231.8+121622 system consists of an M dwarf primary and a directly imaged low-mass stellar companion. We use high resolution spectroscopic data from Keck/KPIC to estimate the objects' atmospheric parameters and radial velocities (RVs). Using PHOENIX stellar models, we find that the primary has a temperature of 3460 $\pm$ 50 K a metallicity of 0.16 $\pm$ 0.04, while the secondary has a temperature of 2510 $\pm$ 50 K and a metallicity of $0.13\substack{+0.12 \\ -0.11}$. Recent work suggests this system is associated with the Hyades, placing it an older age than previous estimates. Both metallicities agree with current $[Fe/H]$ Hyades measurements (0.11 -- 0.21). Using stellar evolutionary models, we obtain significantly higher masses for the objects, of 0.30 $\pm$ 0.15 $M_\odot$ and 0.08 $\pm$ 0.01 $M_\odot$ (84 $\pm$ 11 $M_{Jup}$) respectively. Using the RVs and a new astrometry point from Keck/NIRC2, we find that the system is likely an edge-on, moderately eccentric ($0.41\substack{+0.27 \\ -0.08}$) configuration. We also estimate the C/O ratio of both objects using custom grid models, obtaining 0.42 $\pm$ 0.10 (primary) and 0.55 $\pm$ 0.10 (companion). From these results, we confirm that this system most likely went through a binary star formation process in the Hyades. The significant changes in this system's parameters since its discovery highlight the importance of high resolution spectroscopy for both orbital and atmospheric characterization of directly imaged companions., Comment: 30 pages, 18 figures, accepted for publication in AJ
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- 2024
25. Generalized Linear Bandits with Limited Adaptivity
- Author
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Sawarni, Ayush, Das, Nirjhar, Barman, Siddharth, and Sinha, Gaurav
- Subjects
Computer Science - Machine Learning - Abstract
We study the generalized linear contextual bandit problem within the constraints of limited adaptivity. In this paper, we present two algorithms, $\texttt{B-GLinCB}$ and $\texttt{RS-GLinCB}$, that address, respectively, two prevalent limited adaptivity settings. Given a budget $M$ on the number of policy updates, in the first setting, the algorithm needs to decide upfront $M$ rounds at which it will update its policy, while in the second setting it can adaptively perform $M$ policy updates during its course. For the first setting, we design an algorithm $\texttt{B-GLinCB}$, that incurs $\tilde{O}(\sqrt{T})$ regret when $M = \Omega\left( \log{\log T} \right)$ and the arm feature vectors are generated stochastically. For the second setting, we design an algorithm $\texttt{RS-GLinCB}$ that updates its policy $\tilde{O}(\log^2 T)$ times and achieves a regret of $\tilde{O}(\sqrt{T})$ even when the arm feature vectors are adversarially generated. Notably, in these bounds, we manage to eliminate the dependence on a key instance dependent parameter $\kappa$, that captures non-linearity of the underlying reward model. Our novel approach for removing this dependence for generalized linear contextual bandits might be of independent interest., Comment: Reorganization; New Experiments
- Published
- 2024
26. $p$-Adic hypergeometric functions and certain weight three newforms
- Author
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Sulakashna and Barman, Rupam
- Subjects
Mathematics - Number Theory - Abstract
For an odd prime $p$ and a positive integer $n$, let ${_n}G_n[\cdots]_p$ denote McCarthy's $p$-adic hypergeometric function. In this article, we prove $p$-adic analogue of certain classical hypergeometric identities and using these identities we express the $p$-th Fourier coefficient of certain weight three newforms in terms of special values of ${_3}G_3[\cdots]_p$. Rodriguez-Villegas conjectured certain supercongruences between values of truncated hypergeometric series and the $p$-th Fourier coefficients of these newforms. As a consequence of our main results, we obtain another proof of these supercongruences which were earlier proved by Mortenson and Sun., Comment: 17 pages
- Published
- 2024
27. A Gravitational M\'enage \`a Trois: leptogenesis, primordial gravitational wave & PBH-induced reheating
- Author
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Barman, Basabendu, Das, Suruj Jyoti, Haque, Md Riajul, and Mambrini, Yann
- Subjects
High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics ,High Energy Physics - Theory - Abstract
We explore the possibility of %dynamically producing the observed matter-antimatter asymmetry of the Universe uniquely from the evaporation of primordial black holes (PBH) that are formed in an inflaton-dominated background. Considering the inflaton $(\phi)$ to oscillate in a monomial potential $V(\phi)\propto\phi^n$, we show, it is possible to obtain the desired baryon asymmetry via vanilla leptogenesis from evaporating PBHs of initial mass $\lesssim 10$ g. We find that the allowed parameter space is heavily dependent on the shape of the inflaton potential during reheating (determined by the exponent of the potential $n$), the energy density of PBHs (determined by $\beta$), and the nature of the coupling between the inflaton and the Standard Model (SM). To complete the minimal gravitational framework, we also include in our analysis the gravitational leptogenesis set-up through inflaton scattering via exchange of graviton, which opens up an even larger window for PBH mass, depending on the background equation of state. We finally illustrate that such gravitational leptogenesis scenarios can be tested with upcoming gravitational wave (GW) detectors, courtesy of the blue-tilted primordial GW with inflationary origin, thus paving a way to probe a PBH-induced reheating together with leptogenesis., Comment: 22 pages, 11 figures, 2 tables
- Published
- 2024
28. On the $p$-adic valuation of third order linear recurrence sequences
- Author
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Antony, Deepa and Barman, Rupam
- Subjects
Mathematics - Number Theory - Abstract
In a recent paper, Bilu et al. studied a conjecture of Marques and Lengyel on the $p$-adic valuation of the Tribonacci sequence. In this article, we do a similar study on the $p$-adic valuation of third order linear recurrence sequences by considering a generalisation of the conjecture of Marques and Lengyel for third order linear recurrence sequences. We obtain analogues of the results of Bilu et al. for certain third order linear recurrence sequences. Also, as a consequence of the conjecture, we prove that the solution set of the Diophantine equation given by $x_n=m!$ in positive integers $n,m$ is finite for certain third order linear recurrence sequences $(x_n)$., Comment: 12 pages
- Published
- 2024
29. Reinforcement Learning Jazz Improvisation: When Music Meets Game Theory
- Author
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Tapiavala, Vedant, Piesner, Joshua, Barman, Sourjyamoy, and Fu, Feng
- Subjects
Physics - Physics and Society ,Computer Science - Artificial Intelligence ,Computer Science - Machine Learning ,Computer Science - Sound ,Electrical Engineering and Systems Science - Audio and Speech Processing - Abstract
Live performances of music are always charming, with the unpredictability of improvisation due to the dynamic between musicians and interactions with the audience. Jazz improvisation is a particularly noteworthy example for further investigation from a theoretical perspective. Here, we introduce a novel mathematical game theory model for jazz improvisation, providing a framework for studying music theory and improvisational methodologies. We use computational modeling, mainly reinforcement learning, to explore diverse stochastic improvisational strategies and their paired performance on improvisation. We find that the most effective strategy pair is a strategy that reacts to the most recent payoff (Stepwise Changes) with a reinforcement learning strategy limited to notes in the given chord (Chord-Following Reinforcement Learning). Conversely, a strategy that reacts to the partner's last note and attempts to harmonize with it (Harmony Prediction) strategy pair yields the lowest non-control payoff and highest standard deviation, indicating that picking notes based on immediate reactions to the partner player can yield inconsistent outcomes. On average, the Chord-Following Reinforcement Learning strategy demonstrates the highest mean payoff, while Harmony Prediction exhibits the lowest. Our work lays the foundation for promising applications beyond jazz: including the use of artificial intelligence (AI) models to extract data from audio clips to refine musical reward systems, and training machine learning (ML) models on existing jazz solos to further refine strategies within the game., Comment: 16 pages, 4 figures
- Published
- 2024
30. Electrically controlled focusing of de Broglie matter waves by Fresnel zone plate
- Author
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Barman, Sushanta and Bhattacharjee, Sudeep
- Subjects
Quantum Physics - Abstract
The evolution from classical to quantum matter wave optics has been influenced by transformative optical devices. Fresnel zone plates (FZP), initially designed for light manipulation, have now found expanded applications in matter waves. In this study, focusing of helium atoms by an electrically biased FZP is investigated numerically. The $n$th opaque zone of the FZP is subject to electrostatic biasing using three ways: (i) $V_n=V_1$, where $V_1$ is the biasing voltage applied to the central zone, (ii) $V_n=V_1 \sqrt{n}$, and (iii) $V_n = V_1 \sin (k_E n)$, with $k_E$ being the radial modulation factor. The effect of biasing the FZP on the transmission coefficient ($T_c$), focal length ($f$), size of the focused wave packet ($\sigma_F$), transverse intensity profile, and focusing efficiency ($\eta$) is investigated. The study reveals that the electrical biasing of the FZP modulates the diffractive focusing of neutral atoms by altering the atom-surface interaction with induced polarization potential. It is observed that biasing with $V_n=V_1$ induces multi-focusing of the FZP, reducing wave packet transmission and focusing efficiency. Biasing with $V_n=V_1 \sqrt{n}$ significantly enhances the transmission coefficient by $23.7\%$, increases the focal length $f$ by $103\%$, and improves the focusing efficiency from $10\%$ to $20.17\%$, indicating enhanced focusing performance. Biasing with $V_n=V_1 \sin(k_E n)$ offers increased controllability in focusing matter waves through the parameters $k_E$ and $V_1$. In this case, a highly intense focused wave packet with a better efficiency of $20.3\%$ is observed compared to the other cases. The findings will be helpful in various emerging applications of atom optics, such as improving the performance of helium microscopes, enabling control in cold atom trapping on atom chips, and high-precision atom lithography for quantum electronic devices., Comment: 20 pages, 13 figures
- Published
- 2024
31. Current status of the light neutralino thermal dark matter in the phenomenological MSSM
- Author
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Barman, Rahool Kumar, Bélanger, Genevieve, Bhattacherjee, Biplob, Godbole, Rohini, and Sengupta, Rhitaja
- Subjects
High Energy Physics - Phenomenology ,High Energy Physics - Experiment - Abstract
In a previous publication, we studied the parameter space of the phenomenological Minimal Supersymmetric Standard Model (pMSSM) with a light neutralino thermal dark matter ($M_{\tilde{\chi}_1^0} \leq M_h/2$) and observed that the recent results from the dark matter and collider experiments put strong constraints on this scenario. In this work, we present in detail the arguments behind the robustness of this result against scanning over the large number of parameters in pMSSM. The Run-3 of LHC will be crucial in probing the surviving regions of the parameter space. We further investigate the impact of light staus on our parameter space and also provide benchmarks which can be interesting for Run-3 of LHC. We analyse these benchmarks at the LHC using the machine learning framework of \texttt{XGBOOST}. Finally, we also discuss the effect of non-standard cosmology on the parameter space., Comment: 34 pages, 22 figures, 8 tables
- Published
- 2024
32. The effect of exotic nuclear structure in determining the abundance of heavy elements in explosive nucleosynthesis
- Author
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Barman, J., Barman, R., Parashar, K., and Chatterjee, R.
- Published
- 2024
- Full Text
- View/download PDF
33. Reduction of Emissions in Diesel Engine Using Blended Diesel with Edible Bran Oil
- Author
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Singh, A. K., Barman, S., Mondal, P., and Barman, N.
- Published
- 2024
- Full Text
- View/download PDF
34. Lessons from a Statewide Transfer Grant Program: Impacts of the Texas Transfer Grant Pilot Program on Community College Student Transfer
- Author
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MDRC, Texas Higher Education Coordinating Board (THECB), John Diamond, Sukanya Barman, Rebekah O’Donoghue, and Erick Alonzo
- Abstract
More than half of community college students nationwide intend to pursue a four-year degree; however, in Texas only one in four community college students transfer to four-year institutions successfully. Among students who do transfer to a Texas four-year institution, roughly 60 percent go on to graduate with a bachelor's degree. The result is that only about 15 percent of Texans who start at a community college end up graduating from a four-year institution. To improve transfer rates and, ultimately, bachelor's degree attainment, the Texas Higher Education Coordinating Board (THECB) launched the Texas Transfer Grant Pilot Program with money provided by the U.S. Department of Education's Governor's Emergency Education Relief (GEER) Fund. MDRC evaluated the pilot program to build evidence about its efficacy and help inform future THECB decisions about the program. This policy brief follows up with additional findings about the pilot program's impact on students' enrollment and academic outcomes at Texas four-year institutions during the fall 2022 and spring 2023 semesters--two semesters after students initially received the fall 2022 transfer grant.
- Published
- 2024
35. Accretion, greybody factor, quasinormal modes, power spectrum, sparsity of Hawking radiation, and weak gravitational lensing of a minimum measurable length inspired Schwarzchild black hole
- Author
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Barman, Himangshu, Al-Badawi, Ahmad, Jha, Sohan Kumar, and Rahaman, Anisur
- Subjects
General Relativity and Quantum Cosmology - Abstract
In this manuscript, we delve into an analytic and numerical probe of shadow with different accretion models, quasinormal modes, Hawking radiation, and gravitational lensing to study observational impacts of quantum effect introduced throughh linear-quadratic GUP(LQG). Our investigation reveals that the shadows of LQG modified black holes are smaller and brighter than Schwarzschild black holes. To examine the impact of the quantum correction on the quasinormal mode, linear-quadratic GUP modified black holes are explored under scalar and electromagnetic field perturbation. Here, linear-quadratic GUP is used to capture quantum corrections. It is observed that the incorporation of quantum correction by linear-quadratic GUP alters the singularity structure of the black hole. To compute the quasinormal modes of this linear-quadratic GUP-inspired quantum-corrected black holes, we compute the effective potential generated under the perturbation of scalar and electromagnetic field, and then we use the sixth-order WKB approach in conjunction with the appropriate numerical analysis. We find that the greybody factor decreases with the GUP parameter $\alpha$ implying that the probability of transmission decreases with the GUP parameter. The total power emitted by LQG modified black hole is found to be greater than that emitted by Schwarzschild black hole. Finally, we study weak gravitational lensing and make a comparison with quadratic GUP and linear GUP modified black holes.
- Published
- 2024
36. Convolutional Neural Networks can achieve binary bail judgement classification
- Author
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Barman, Amit, Roy, Devangan, Paul, Debapriya, Dutta, Indranil, Guha, Shouvik Kumar, Karmakar, Samir, and Naskar, Sudip Kumar
- Subjects
Computer Science - Computation and Language ,Computer Science - Computers and Society ,Computer Science - Machine Learning - Abstract
There is an evident lack of implementation of Machine Learning (ML) in the legal domain in India, and any research that does take place in this domain is usually based on data from the higher courts of law and works with English data. The lower courts and data from the different regional languages of India are often overlooked. In this paper, we deploy a Convolutional Neural Network (CNN) architecture on a corpus of Hindi legal documents. We perform a bail Prediction task with the help of a CNN model and achieve an overall accuracy of 93\% which is an improvement on the benchmark accuracy, set by Kapoor et al. (2022), albeit in data from 20 districts of the Indian state of Uttar Pradesh., Comment: Accepted on 20th International Conference on Natural Language Processing (ICON)
- Published
- 2024
37. Attentive Fusion: A Transformer-based Approach to Multimodal Hate Speech Detection
- Author
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Mandal, Atanu, Roy, Gargi, Barman, Amit, Dutta, Indranil, and Naskar, Sudip Kumar
- Subjects
Computer Science - Computation and Language ,Computer Science - Machine Learning ,Computer Science - Sound ,Electrical Engineering and Systems Science - Audio and Speech Processing ,Electrical Engineering and Systems Science - Signal Processing - Abstract
With the recent surge and exponential growth of social media usage, scrutinizing social media content for the presence of any hateful content is of utmost importance. Researchers have been diligently working since the past decade on distinguishing between content that promotes hatred and content that does not. Traditionally, the main focus has been on analyzing textual content. However, recent research attempts have also commenced into the identification of audio-based content. Nevertheless, studies have shown that relying solely on audio or text-based content may be ineffective, as recent upsurge indicates that individuals often employ sarcasm in their speech and writing. To overcome these challenges, we present an approach to identify whether a speech promotes hate or not utilizing both audio and textual representations. Our methodology is based on the Transformer framework that incorporates both audio and text sampling, accompanied by our very own layer called "Attentive Fusion". The results of our study surpassed previous state-of-the-art techniques, achieving an impressive macro F1 score of 0.927 on the Test Set., Comment: Accepted in 20th International Conference on Natural Language Processing (ICON)
- Published
- 2024
38. Bj{\o}ntegaard Delta (BD): A Tutorial Overview of the Metric, Evolution, Challenges, and Recommendations
- Author
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Barman, Nabajeet, Martini, Maria G., and Reznik, Yuriy
- Subjects
Computer Science - Multimedia ,Computer Science - Information Theory ,Electrical Engineering and Systems Science - Image and Video Processing - Abstract
The Bj{\o}ntegaard Delta (BD) method proposed in 2001 has become a popular tool for comparing video codec compression efficiency. It was initially proposed to compute bitrate and quality differences between two Rate-Distortion curves using PSNR as a distortion metric. Over the years, many works have calculated and reported BD results using other objective quality metrics such as SSIM, VMAF and, in some cases, even subjective ratings (mean opinion scores). However, the lack of consolidated literature explaining the metric, its evolution over the years, and a systematic evaluation of the same under different test conditions can result in a wrong interpretation of the BD results thus obtained. Towards this end, this paper presents a detailed tutorial describing the BD method and example cases where the metric might fail. We also provide a detailed history of its evolution, including a discussion of various proposed improvements and variations over the last 20 years. In addition, we evaluate the various BD methods and their open-source implementations, considering different objective quality metrics and subjective ratings taking into account different RD characteristics. Based on our results, we present a set of recommendations on using existing BD metrics and various insights for possible exploration towards developing more effective tools for codec compression efficiency evaluation and comparison.
- Published
- 2024
39. Bilayer stanene on a magnetic topological insulator
- Author
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Barman, Sajal, Bhakuni, Pramod, Sarkar, Shuvam, Bhattacharya, Joydipto, Balal, Mohammad, Pariari, Arnab, Huecker, Markus, Batabyal, Rajib, Chakrabarti, Aparna, and Barman, Sudipta Roy
- Subjects
Condensed Matter - Materials Science - Abstract
A two-dimensional superconducting adlayer grown on a magnetic topological insulator (MTI) has the potential to exhibit proximity induced superconductivity, facilitate the existence of Majorana fermions and find applications in the field of quantum computing. In this work, we demonstrate the formation of bilayer stanene on an MTI substrate, specifically Mn(Bi$_{0.74}$Sb$_{0.26}$)$_2$Te$_4$ (MBST), through utilization of a combination of techniques such as angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy (STM), density functional theory (DFT), x-ray photoelectron spectroscopy (XPS), and low energy electron diffraction (LEED). The stanene related bands observed in ARPES have been corroborated by our DFT calculations. Atomic resolution STM topography images confirm the formation of monolayer as well as bilayer stanene. A buffer layer -- formed due to chemical bonding of Sn with the upper two layers of MBST (Te and Bi/Sb) -- facilitates the growth of stanene., Comment: *Both authors contributed equally
- Published
- 2023
40. Testing Axionic Dark Matter during Gravitational Reheating
- Author
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Barman, Basabendu and Datta, Arghyajit
- Subjects
High Energy Physics - Phenomenology ,Astrophysics - Cosmology and Nongalactic Astrophysics - Abstract
Assuming axions are potential dark matter (DM) candidate that make up all of the DM abundance, we discuss production of axions via (i) standard misalignment mechanism during the period of reheating and (ii) graviton-mediated 2-to-2 scattering of the inflaton and bath particles, where the inflaton $\phi$ oscillates in a monomial potential $V(\phi)\propto\phi^k$ with a general equation of state. Considering reheating takes place purely gravitationally, mediated by massless gravitons, we explore the viable region of the parameter space that agrees with the observed DM relic abundance, satisfying bounds from big bang nucleosynthesis (BBN) and cosmic microwave background radiation (CMB). We also discuss complementarity between dedicated axion search experiments and futuristic gravitational wave search facilities in probing the viable parameter space., Comment: 25 pages, 6 figures, version accepted for PRD
- Published
- 2023
41. Parameterized Guarantees for Almost Envy-Free Allocations
- Author
-
Barman, Siddharth, Kar, Debajyoti, and Pathak, Shraddha
- Subjects
Computer Science - Computer Science and Game Theory - Abstract
We study fair allocation of indivisible goods among agents with additive valuations. We obtain novel approximation guarantees for three of the strongest fairness notions in discrete fair division, namely envy-free up to the removal of any positively-valued good (EFx), pairwise maximin shares (PMMS), and envy-free up to the transfer of any positively-valued good (tEFx). Our approximation guarantees are in terms of an instance-dependent parameter $\gamma \in (0,1]$ that upper bounds, for each indivisible good in the given instance, the multiplicative range of nonzero values for the good across the agents. First, we consider allocations wherein, between any pair of agents and up to the removal of any positively-valued good, the envy is multiplicatively bounded. Specifically, the current work develops a polynomial-time algorithm that computes a $\left( \frac{2\gamma}{\sqrt{5+4\gamma}-1}\right)$-approximately EFx allocation for any given fair division instance with range parameter $\gamma \in (0,1]$. For instances with $\gamma \geq 0.511$, the obtained approximation guarantee for EFx surpasses the previously best-known approximation bound of $(\phi-1) \approx 0.618$, here $\phi$ denotes the golden ratio. Furthermore, for $\gamma \in (0,1]$, we develop a polynomial-time algorithm for finding allocations wherein the PMMS requirement is satisfied, between every pair of agents, within a multiplicative factor of $\frac{5}{6} \gamma$. En route to this result, we obtain novel existential and computational guarantees for $\frac{5}{6}$-approximately PMMS allocations under restricted additive valuations. Finally, we develop an algorithm that efficiently computes a $2\gamma$-approximately tEFx allocation. Specifically, we obtain existence and efficient computation of exact tEFx allocations for all instances with $\gamma \in [0.5, 1]$., Comment: 28 pages
- Published
- 2023
42. Quasiperiodic gallium adlayer on i-Al-Pd-Mn
- Author
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Bhakuni, Pramod, Krajčí, Marian, and Barman, Sudipta Roy
- Subjects
Condensed Matter - Materials Science - Abstract
Using scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and density functional theory (DFT), we demonstrate the formation of quasicrystalline gallium adlayer on icosahedral ($i$)-Al-Pd-Mn. Quasiperiodic motifs are evident in the STM topography images, including the Ga white flower (GaWF) and $\tau$ inflated GaWF ($\tau$-GaWF), where $\tau$ is the golden mean. A larger and more complicated ring motif is also identified, comprised of a bright center and an outer ring of pentagons. The fast Fourier transform of the STM images exhibits distinct quasiperiodic spots, thereby establishing quasiperiodicity on a length scale of $\sim$350 nm. Based on our DFT calculations, the preferred adsorption sites of Ga on i-Al-Pd-Mn are determined to be either the Mn atoms at the center of the Penrose P1 tile or the vertices of the P1 tile containing Pd atoms at the center of a cluster of 5 Al atoms (5-Al). The GaWF motif is modeled by an inner 6 atom Ga cluster (6-Ga) around the central Mn atom and an outer ring of 5 Ga atoms adsorbed at the centers of the 5-Al clusters, both having pentagonal symmetry. The $\tau$-GaWF motif is modeled by the 6-Ga arranged on the $\tau$-P1 tiling, while the ring motif is modeled by Ga atoms adsorbed at the center of 5-Al clusters above a Pd atom. The side lengths and diameters of the GaWF, $\tau$-GaWF, and the ring motifs are $\tau$ scaled and show excellent agreement with the DFT-based models. An additional indication of the quasiperiodic characteristics of the Ga monolayer is the 5-fold LEED patterns that were detected throughout the entire range of beam energy that was measured., Comment: 12 pages, 6 figures
- Published
- 2023
- Full Text
- View/download PDF
43. Tripartite Phonon-Magnon-Plasmon Coupling, Parametric Amplification, and Formation of a Phonon-Magnon-Plasmon Polariton in a Two-Dimensional Periodic Array of Magnetostrictive/Plasmonic Bilayered Nanodots
- Author
-
Pal, Sreya, Pal, Pratap Kumar, Fabiha, Raisa, Bandyopadhyay, Supriyo, and Barman, Anjan
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Coupling between spin waves (SWs) and other types of waves in nanostructured magnetic media has garnered increased attention in recent years because of the rich physics and the potential to produce disruptive technologies. Among this family of intriguing phenomena, we recently reported a new one: coupling between SWs and hybridized phonon-plasmon waves, resulting in tripartite coupling of magnons, phonons, and plasmons. Here, this acousto-plasmo-magnonic phenomenon is studied in a two-dimensional periodic array of bilayered [Co/Al] nanodots on a silicon substrate, where the Co is a magnetostrictive constituent responsive to magneto-elastic coupling and the Al acts as a source of surface plasmons. Time-resolved magneto-optical-Kerr-effect microscopy revealed parametric amplification and strong coupling between two spin wave modes mediated by a hybrid phonon-plasmon wave. The strong coupling forms a new quasi-particle: the phonon-plasmonmagnon polariton., Comment: 8 pages, 5 figures (Main manuscript); 3 pages, 1 figure (Supplemental material)
- Published
- 2023
44. Nearly Equitable Allocations Beyond Additivity and Monotonicity
- Author
-
Barman, Siddharth, Bhaskar, Umang, Pandit, Yeshwant, and Pyne, Soumyajit
- Subjects
Computer Science - Computer Science and Game Theory - Abstract
Equitability (EQ) in fair division requires that items be allocated such that all agents value the bundle they receive equally. With indivisible items, an equitable allocation may not exist, and hence we instead consider a meaningful analog, EQx, that requires equitability up to any item. EQx allocations exist for monotone, additive valuations. However, if (1) the agents' valuations are not additive or (2) the set of indivisible items includes both goods and chores (positively and negatively valued items), then prior to the current work it was not known whether EQx allocations exist or not. We study both the existence and efficient computation of EQx allocations. (1) For monotone valuations (not necessarily additive), we show that EQx allocations always exist. Also, for the large class of weakly well-layered valuations, EQx allocations can be found in polynomial time. Further, we prove that approximately EQx allocations can be computed efficiently under general monotone valuations. (2) For non-monotone valuations, we show that an EQx allocation may not exist, even for two agents with additive valuations. Under some special cases, however, we establish existence and efficient computability of EQx allocations. This includes the case of two agents with additive valuations where each item is either a good or a chore, and there are no mixed items. In addition, we show that, under nonmonotone valuations, determining the existence of EQx allocations is weakly NP-hard for two agents and strongly NP-hard for more agents., Comment: 28 pages
- Published
- 2023
45. Universal role of curvature in vacuum entanglement
- Author
-
K, Hari, Barman, Subhajit, and Kothawala, Dawood
- Subjects
General Relativity and Quantum Cosmology ,High Energy Physics - Theory ,Quantum Physics - Abstract
We highlight some universal features concerning the role of spacetime curvature in the entanglement induced between quantum probes coupled to a quantum field in a suitable vacuum state. The probes are initially causally disconnected and non-entangled. We explore the parameter space $\{{\omega}, d_0, \boldsymbol{v}_0\}$ spanned by the energy gap $\omega$ of the detectors, and the initial values of separation distance $d_0$ and relative velocity $\boldsymbol{v}_0$, both covariantly defined in arbitrary curved spacetime. We also obtain numerical results in de Sitter spacetimes and use these to explore strong curvature regime, while also corroborating our perturbative results in arbitrary curved spacetime. Our analysis shows that curvature can induce entanglement features in certain regions of the above parameter space, in a manner which facilitates using entanglement as a probe of spacetime curvature., Comment: Published in PRD, 28 pages and 15 figures
- Published
- 2023
- Full Text
- View/download PDF
46. Majorana neutrinos in Double Inverse Seesaw and $\boldsymbol{\Delta(54)}$ Flavor Models
- Author
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Bora, Hrishi, Francis, Ng. K., Barman, Animesh, and Thapa, Bikash
- Subjects
High Energy Physics - Phenomenology - Abstract
The present study entails the augmentation of the $\Delta$(54) flavor symmetry model by including the ISS mechanism by two Standard Model Higgs particles, achieved by the inclusion of different flavons. The matrices are discussed numerically in the framework of the $\Delta(54)$ flavor model with the ISS mechanism for Majorana neutrinos. We introduced Vector like (VL) fermions and a Weyl fermion, which are gauge singlets in the Standard Model. We restrict the undesirable terms in our Lagrangian using additional symmetry. Due to the addition of additional flavons, the precise tribimaximal neutrino mixing pattern deviates, resulting in the creation of a non-zero reactor angle $\theta_{13}$. We found that the atmospheric oscillation parameter ($\theta_{23}$) occupies the upper octant under the normal hierarchy situation. We also study the CP violation ($\delta_{CP}$) , Jarlskog invariant parameter ($J$), and Neutrinoless double-beta decay parameter ($m_{ee}$) in the parameter space of the normal hierarchy model to see whether they accord with the most recent neutrino observations., Comment: 17 pages, 5 figures, 2 tables
- Published
- 2023
- Full Text
- View/download PDF
47. Secure Data Transmission over Insecure Radio Channel in Wireless of Things (WoT) Network
- Author
-
Barman, Prokash and Saha, Banani
- Subjects
Computer Science - Cryptography and Security - Abstract
Potential capacity of processors is enhancing rapidly which leads to the increase of computational ability of the adversary. As a result, the required key size for conventional encryption techniques is growing everyday for complex unbreakable security communication systems. The Public Key Cryptography (PKC) techniques which use larger keys cannot be fitted in tiny resource constrained Wireless of Things (WoT) devices. Some Symmetric Key Cryptosystems (SKC) use smaller keys, which can be fitted in the tiny devices. But in large networks where the number of nodes is in the order of 103, the memory constraint does not allow the system to do so. The existing secure data communication in insecure medium uses various conventional encryption methods like Public Key Cryptography (PKC) and Symmetric Key Cryptosystems (SKC). Generally, modern encryption methods need huge processing power, memory and time. Also in some cases, Key Pre-distribution System (KPS) is used among different communicating devices. With the growing need for larger key size in the conventional secure communication system, the existing resources in the communicating devices suffer from resource starvation. Hence, the need of a novel mechanism for secure communication is inevitable. But the existing secure communication mechanisms like PKC, SKC or KPS do not ensure elimination of resource starvation issue in tiny devices during communication. In these existing conventional mechanisms, the plain text is generally converted into cipher text with greater size than the plain text at the device level, which leads to resource starvation. At the time of transmission, the cipher text at the device end requires more bandwidth than the plain text which puts bandwidth overhead on the broadcast channel (BC).
- Published
- 2023
48. An Efficient Elliptic Curve Cryptography Arithmetic Using Nikhilam Multiplication
- Author
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Barman, Prokash and Saha, Banani
- Subjects
Computer Science - Cryptography and Security - Abstract
Multiplication is one of the most important operation in Elliptic Curve Cryptography (ECC) arithmetic. For point addition and point doubling in ECC scalar (integer) multiplication is required. In higher order classical (standard) multiplication many intermediate operations are required. Reduced operation in multiplication will increase the functional speed of ECC arithmetic. These goals can be achieved using ancient multiplication algorithm namely Nikhilam Sutra. Nikhilam Sutra is one of the Sutra (algorithm) within 16 Vedic mathematics Sutras (algorithms). Nikhilam Sutra is efficient for multiplying two large decimal numbers. The Sutra reduces multiplication of two large numbers into two smaller numbers multiplication. The functional speed of Elliptic Curve Cryptography can be increased using Nikhilam method for scalar multiplication.
- Published
- 2023
49. Enhancement of spin to charge conversion efficiency at the topological surface state by inserting normal metal spacer layer in the topological insulator based heterostructure
- Author
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Pal, Sayani, Nandi, Anuvab, Nath, Shambhu G., Pal, Pratap Kumar, Sharma, Kanav, Manna, Subhadip, Barman, Anjan, and Mitra, Chiranjib
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
We report efficient spin to charge conversion (SCC) in the topological insulator (TI) based heterostructure ($BiSbTe_{1.5}Se_{1.5}/Cu/Ni_{80}Fe_{20}$) by using spin-pumping technique where $BiSbTe_{1.5}Se_{1.5}$ is the TI and $Ni_{80}Fe_{20}$ is the ferromagnetic layer. The SCC, characterized by inverse Edelstein effect length ($\lambda_{IEE}$) in the TI material gets altered with an intervening Copper (Cu) layer and it depends on the interlayer thickness. The introduction of Cu layer at the interface of TI and ferromagnetic metal (FM) provides a new degree of freedom for tuning the SCC efficiency of the topological surface states. The significant enhancement of the measured spin-pumping voltage and the linewidth of ferromagnetic resonance (FMR) absorption spectra due to the insertion of Cu layer at the interface indicates a reduction in spin memory loss at the interface that resulted from the presence of exchange coupling between the surface states of TI and the local moments of ferromagnetic metal. The temperature dependence (from 8K to 300K) of the evaluated $\lambda_{IEE}$ data for all the trilayer systems, TI/Cu/FM with different Cu thickness confirms the effect of exchange coupling between the TI and FM layer on the spin to charge conversion efficiency of the topological surface state.
- Published
- 2023
50. Glioblastoma Tumor Segmentation using an Ensemble of Vision Transformers
- Author
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Liu, Huafeng, Dowdell, Benjamin, Engelder, Todd, Pulmano, Zarah, Osa, Nicolas, and Barman, Arko
- Subjects
Electrical Engineering and Systems Science - Image and Video Processing ,Computer Science - Computer Vision and Pattern Recognition ,Computer Science - Machine Learning - Abstract
Glioblastoma is one of the most aggressive and deadliest types of brain cancer, with low survival rates compared to other types of cancer. Analysis of Magnetic Resonance Imaging (MRI) scans is one of the most effective methods for the diagnosis and treatment of brain cancers such as glioblastoma. Accurate tumor segmentation in MRI images is often required for treatment planning and risk assessment of treatment methods. Here, we propose a novel pipeline, Brain Radiology Aided by Intelligent Neural NETworks (BRAINNET), which leverages MaskFormer, a vision transformer model, and generates robust tumor segmentation maks. We use an ensemble of nine predictions from three models separately trained on each of the three orthogonal 2D slice directions (axial, sagittal, and coronal) of a 3D brain MRI volume. We train and test our models on the publicly available UPenn-GBM dataset, consisting of 3D multi-parametric MRI (mpMRI) scans from 611 subjects. Using Dice coefficient (DC) and 95% Hausdorff distance (HD) for evaluation, our models achieved state-of-the-art results in segmenting all three different tumor regions -- tumor core (DC = 0.894, HD = 2.308), whole tumor (DC = 0.891, HD = 3.552), and enhancing tumor (DC = 0.812, HD = 1.608).
- Published
- 2023
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