Search

There is a growing interest in using pulsed high magnetic field as a controlling parameter of physical phenomena in various scientific disciplines, such as condensed matter physics, particle physics, plasma physics, chemistry, and biological studies. We devised a concise and portable pulsed magnetic field generator that produces a 40 T field with a pulse duration of 2 ms. It is assembled using only off-the-shelf components and a homemade coil that leverages small computers, Raspberry Pi, and Python codes. It allows for straightforward modification for general purposes. As working examples, we show representative applications in condensed matter experiments of magnetoresistance, magnetization, and magnetostriction measurements for graphite, NdNi 2 P 2 , and NdCo 2 P 2 , respectively, with the maximum magnetic field of 41 T and the lowest temperature of 4.2 K. [ABSTRACT FROM AUTHOR]

Through Monte Carlo modeling, it is shown that the statistics of electron–hole pair creation in semiconductors (and by extension, presumably, ion-pair creation in gas proportional counters) are substantially different for fast electrons (and by extension, presumably, alpha particles, ions, etc.) cf. x-ray/γ-ray photons. New variables are introduced to quantify the differences in the statistics: the loss parameter, ζ(E′), which acts on the average e−–h+ pair creation energy; and the broadening factor, B(E′), which acts on the Fano factor. E′ is the initial energy of the fast electron. ζ(E′) and B(E′) are computed for a variety of semiconductor materials. A new equation for the statistically limited energy resolution of a particle counting fast electron spectrometer is established. This new equation supersedes and replaces that for the Fano-limited energy resolution of a particle counting fast electron spectrometer. The implications impact a wide variety of fields wherever fast electrons (or alpha particles, ions, etc.) and/or Fano statistics are used; this includes, inter alia, quantum computing, x-ray excitonics, space science, optoelectronics, nuclear engineering, particle physics, photovoltaics, and even neural response variability in the brain. [ABSTRACT FROM AUTHOR]

The Microwave SQUID Multiplexer (μ MUX) is the device of choice for the readout of a large number of low-temperature detectors in a wide variety of experiments within the fields of astronomy and particle physics. While it offers large multiplexing factors, the system noise performance is highly dependent on the cold- and warm-readout electronic systems used to read it out, as well as the demodulation domain and parameters chosen. In order to understand the impact of the readout systems in the overall detection system noise performance, first, we extended the available μ MUX simulation frameworks, including additive and multiplicative noise sources in the probing tones (i.e., phase and amplitude noise), along with the capability of demodulating the scientific data, either in the resonator's phase or the scattering amplitude. Then, considering the additive noise as a dominant noise source, the optimum readout parameters to achieve minimum system noise were found for both open-loop and flux-ramp demodulation schemes in the aforementioned domains. Later, we evaluated the system noise sensitivity to multiplicative noise sources under the optimum readout parameters. Finally, as a case study, we evaluated the optimal demodulation domain and the expected system noise level for a typical software-defined radio readout system. This work leads to an improved system performance prediction and noise engineering based on the available readout electronics and the selected demodulation domain. [ABSTRACT FROM AUTHOR]

Radio-frequency (RF) cavities, previously employed in particle physics, quantum computing, and gravitational wave research, offer unique advantages in terms of sensitivity and non-invasiveness as a method of sensing motion in both macroscopic and microscopic systems. This research aims to address how an RF cavity can effectively detect and characterize the low-frequency vibratory motion of a room-temperature mm-scale levitated particle. In this case, the particle in question is a diamagnetically levitated slab of highly oriented pyrolytic graphite. Cavity-based identification of the slab's rigid-body modes is substantiated by calculations of the force acting on the particle and validated through slow-motion video object tracking. We find that this system can accurately measure oscillations in all six center-of-mass degrees of freedom. Calculations indicate that this system could potentially detect forces on the scale of tens of femto-Newtons and center of mass displacements of less than 10 nm. This work provides a non-invasive method of conducting position and vibration measurements in the field of levitodynamics without the ultra-cold temperatures or bulky precision laser setups that superconducting quantum interference devices and conventional interferometric methods utilize. [ABSTRACT FROM AUTHOR]

Muons are part of natural cosmic radiation but can also be generated at spallation sources for material science and particle physics applications. Recently, pulsed muons have been used to characterize the density of free charge carriers in semiconductors and their recombination lifetime. Muon beam irradiation can also result in the formation of dilute levels of crystal defects in silicon. These crystal defects are only detected in high carrier lifetime silicon samples that are highly sensitive to defects due to their long recombination lifetimes. This work investigates the characteristics of these defects in terms of their formation, recombination activity, and deactivation. Charge carrier lifetime assessments and photoluminescence imaging have great sensitivity to measure the generated defects in high-quality silicon samples exposed to ∼4 MeV (anti)muons and their recombination activity despite the extremely low concentration. The defects reduce the effective charge carrier lifetime of both p- and n-type silicon and appear to be more detrimental to n-type silicon. Defects are created by transmission of muons through the wafer, and there are indications that slowed or implanted muons may create additional defects. In a post-exposure isochronal annealing study, we observe that annealing at temperatures of up to 450 °C does not by itself fully deactivate the defects. A recovery of charge carrier lifetime was observed when the annealing was combined with Al2O3 surface passivation, probably due to passivation of bulk defects from hydrogen from the dielectric film. [ABSTRACT FROM AUTHOR]

On 2022 September 5, during Parker Solar Probe's (PSP) 13th encounter, a fast shock wave and a related solar energetic particle (SEP) event were observed as the spacecraft approached the perihelion of its orbit. Observations from the Integrated Science Investigation of the Sun (IS⊙IS) instrument suite show that SEPs arrived at the spacecraft with a significant delay from the onset of the parent solar eruption and that the first arriving SEPs exhibited an inverse velocity dispersion (IVD) for energetic protons above ~1 MeV. Utilizing data from multiple spacecraft, we investigate the eruption dynamics and shock wave propagation. Our analysis includes 3D shock modeling and SEP transport simulations to examine the origins of this SEP event and explore the causes of the delayed SEP onset and the observed IVD. The data-driven SEP simulation reproduces the SEP event onset observed at PSP, its evolving energy spectrum, and the IVD. This IVD is attributed to a relatively slow, ongoing particle acceleration process occurring at the flank of the expanding shock wave intercepted by PSP. This has significant implications for the role of shocks in the release of SEPs at widespread events and for methods used to infer the SEP release times. Furthermore, the match between the simulation and observations worsens when cross-field diffusion is considered, indicating that SEP diffusion had a minor effect on this event. These findings underscore the complexity of SEP events and emphasize the need for advanced modeling approaches to better understand the role of shock waves and other physical processes in SEP acceleration and release. [ABSTRACT FROM AUTHOR]

In this paper, we present a three-parameter model for the distributions of “dark matter” around local spherically symmetric and static distributions of normal matter, usually referred to as “dark matter halos”. The model is based on the assumption that the spontaneous symmetry breaking mechanism involving the Higgs field in the standard model of elementary particle physics leads to the existence of a constant distribution of vacuum energy throughout space–time. This is to be interpreted as a constant distribution of proper energy, as measured by local observers in their proper reference frames. Due to the presence of this universal distribution of vacuum energy, the model requires the introduction of the cosmological term in the Einstein field equations, in order to regulate the behavior of the resulting geometry at cosmologically large distances. By implementing the model on galactic scales, we are able to establish the gravitational consequences of such a homogeneous distribution of proper energy density at these scales. This results in equivalent halo masses and orbital velocity curves that, at least qualitatively, match the observations for galactic “dark matter” halos. Although the detailed realization of the model presented and calculated here cannot be construed as a precise representation of galactic structure, given that most of the actual structure of the galaxy, such as the galactic disk itself, is ignored, and replaced by a single spherically symmetric bulge, in this paper we do introduce the conceptual framework that may be used to construct a more complete galactic model in the future. [ABSTRACT FROM AUTHOR]

The International Center for Fundamental Physics in Moscow (ICFPM) was established in 1993 to support young scientists in Russia working in theoretical physics. The center, founded by the Lebedev Physical Institute and NORDITA, aimed to provide funding for researchers facing economic challenges in Russia. Over the years, the center received support from various sources, including the Swedish Ministry of Sciences and the Dynasty Foundation, until it was officially dissolved in 2021 due to funding issues. The center's activities had a significant impact on supporting young scientists in Russia and influenced the development of other programs for scientific research in the country. [Extracted from the article]

Deriving an arrow of time from time-reversal symmetric microscopic dynamics is a fundamental open problem in many areas of physics, ranging from cosmology, to particle physics, to thermodynamics and statistical mechanics. Here we focus on the derivation of the arrow of time in open quantum systems and study precisely how time-reversal symmetry is broken. This derivation involves the Markov approximation applied to a system interacting with an infinite heat bath. We find that the Markov approximation does not imply a violation of time-reversal symmetry. Our results show instead that the time-reversal symmetry is maintained in the derived equations of motion. This imposes a time-symmetric formulation of quantum Brownian motion, Lindblad and Pauli master equations, which hence describe thermalisation that may occur into two opposing time directions. As a consequence, we argue that these dynamics are better described by a time-symmetric definition of Markovianity. Our results may reflect on the formulations of the arrow of time in thermodynamics, cosmology, and quantum mechanics. [ABSTRACT FROM AUTHOR]

The Super Tau Charm Facility (STCF) is a new generation electron–positron collider, proposed to study various physics topics in the tau charm energy region. STCF will operate within a center-of-mass energy spanning 2 to 7GeV, with a peak luminosity of 0.5×1035 cm−2s−1, which means STCF will produce two orders of magnitude more data compared to BESIII each year, posing great challenges for the data processing software. To support the intricate requirements from the offline data processing tasks, as well as to tackle this immense challenge caused by the huge data volume, the offline software for STCF (OSCAR) is designed and developed, based on the state-of-the-art technology and toolkits in the high energy physics community. This paper provides an overview of the design and implementation of OSCAR, highlighting its event data management system, parallel data processing capabilities leveraging SNiPER and TBB, and its geometry management framework powered by DD4hep. Presently, OSCAR is fully operational, effectively supporting the conceptual design of the STCF detector and exploring its vast physics potential. [ABSTRACT FROM AUTHOR]

The article discusses the contributions of John Hopfield and Geoffrey Hinton to artificial neural networks, leading to advancements in artificial intelligence technology. It also recognizes the late Mr. Guangzhao in Chinese science and Prof. Rohini Godbole in Indian collider physics, emphasizing gender equity in STEM. The Division of Plasma Physics (DPP) activities, including conferences and awards, are outlined, with the 2023 AAPPS-DPP conference awarding young researchers in plasma physics. The RMPP journal dedicated to plasma physics has been growing steadily since 2017, and the 2024 AAPPS-APCTP C. N. Yang Awards honored three young scholars for their physics contributions. The text also highlights achievements of physicists worldwide and initiatives by physics societies. [Extracted from the article]

The article "Walking with Lars" published in the International Journal of Modern Physics A reflects on conversations between the author, A. Polyakov, and Lars, a physicist and friend. The discussions touch on various topics in fundamental physics, including the relationship between General Relativity and Quantum Mechanics, the cosmological constant, and the information paradox. The article highlights the challenges in theoretical physics due to the lack of revolutionary experimental discoveries post-Higgs particles and the need for innovative approaches to apply theoretical ideas to diverse physical situations. [Extracted from the article]

Intense sources of very cold neutrons (VCNs) would be beneficial for various neutron scattering techniques and low-energy particle physics experiments. Binary clathrate hydrates hosting deuterated tetrahydrofuran (THF-d) and dioxygen show promise as potential moderators for such sources due to a rich spectrum of localized low-energy excitations of the encaged guest molecules. In this article, we present a reliable manufacturing technique for such hydrates. Neutron diffraction data confirm their clathrate structure as type II (CS-II), determine their purity, and cage occupancy. Furthermore, we present data on the thermal expansivity of THF-d– and THF-d–O2clathrates, drawing attention to them as an interesting case study for the complex structure and dynamics of this class of material. [ABSTRACT FROM AUTHOR]

For the past decade, Majorana quasiparticles have become one of the hot topics in condensed matter research. Besides the fundamental interest in the realization of particles being their own antiparticles, going back to basic concepts of elementary particle physics, Majorana quasiparticles in condensed matter systems offer exciting potential applications in topological quantum computation due to their non-Abelian quantum exchange statistics. Motivated by theoretical predictions about possible realizations of Majorana quasiparticles as zero-energy modes at boundaries of topological superconductors, experimental efforts have focussed in particular on quasi-one-dimensional semiconductor–superconductor and magnet–superconductor hybrid systems. However, an unambiguous proof of the existence of Majorana quasiparticles is still challenging and requires considerable improvements in materials science, atomic-scale characterization and control of interface quality, as well as complementary approaches of detecting various facets of Majorana quasiparticles. Bottom-up atom-by-atom fabrication of disorder-free atomic spin chains on atomically clean superconducting substrates has recently allowed deep insight into the emergence of topological sub-gap Shiba bands and associated Majorana states from the level of individual atoms up to extended chains, thereby offering the possibility for critical tests of Majorana physics in disorder-free model-type 1D hybrid systems. [ABSTRACT FROM AUTHOR]

So-called antimatter in the form of elementary particles such as positive electrons (antielectrons alias positrons) and negative protons (antiprotons) has for long been investigated by physicists. However, atoms or molecules of this exotic kind are conspicuously absent from nature. Since antimatter is believed to be symmetric with ordinary matter, the flagrant asymmetry constitutes a problem that still worries physicists and cosmologists. As first suggested by Paul Dirac in 1933, in distant parts of the universe there might be entire stars and galaxies made of antiparticles alone. Why not? This paper examines how the concepts of antiparticles and antimatter slowly migrated from particle physics to astronomy and cosmology. At around 1970 a few physicists speculated about an anti-universe separate from ours while others looked for the charge asymmetry in quantum processes in the early big-bang explosion of the universe. Others again proposed a ‘plasma cosmology’ that kept our world and the hypothetical world of antimatter apart. Soviet physicists and astronomers were no less interested in the problem than their colleagues in the West. The paper details the development up to the late 1970s, paying attention not only to mainstream scientific works but also to more speculative ideas, some of them very speculative. By that time the antimatter mystery remained mysterious – which is still the situation. [ABSTRACT FROM AUTHOR]

Understanding high energy density physics (HEDP) is critical for advancements in fusion energy and astrophysics. The computational demands of the computer models used for HEDP studies have led researchers to explore deep learning methods to enhance simulation efficiency. This paper introduces HEDP-Gen, a framework for training and evaluating generative models tailored for HEDP. Central to HEDP-Gen is Geom-WAE-a generalized Wasserstein auto-encoder accommodating both Euclidean and non-Euclidean latent spaces. HEDP-Gen establishes a rigorous evaluation standard, assessing not only reconstruction fidelity but also scientific validity, sample diversity, and latent space utility in geodesic interpolation and attribute traversal. A case study using hyperbolic geometry (Poincaréball prior) demonstrates that non-Euclidean priors yield scientifically valid samples and stronger generalization in downstream tasks, advantages often missed by conventional reconstruction metrics. High energy density physics (HEDP) is crucial for advancements in fusion energy and astrophysics, yet its simulations are complex and computationally demanding. The authors introduce HEDP-Gen, a deep learning framework which uses advanced geometry in model design, and show that it enhances simulation efficiency and produces scientifically accurate results. [ABSTRACT FROM AUTHOR]

Here, we will discuss some ideas for possible classical/semi-classical modifications of the black hole solutions in General Relativity (GR). These modifications/extensions include black holes in higher dimensions; black holes with additional gravitational fields, or fields beyond the Standard Model of Particle Physics; black holes in alternative classical theories of gravity and in semiclassical gravity; phenomenological models that extend the GR black hole solutions. [ABSTRACT FROM AUTHOR]

Effective field theory (EFT) is a computationally powerful theoretical framework, finding application in many areas of physics. The framework, applied to the Standard Model of particle physics, is even more empirically successful than our theoretical understanding would lead us to expect. I argue that this is a problem for our understanding of how the Standard Model relates to some successor theory. The problem manifests as two theoretical anomalies involving relevant parameters: the cosmological constant and the Higgs mass. The persistent failure to fix these anomalies from within suggests that the way forward is to go beyond the EFT framework. [ABSTRACT FROM AUTHOR]

We elaborate on the brane configuration that gives rise to a QCD-like gauge theory that confines at low energies and becomes scale invariant at the highest energies. In the limit where the rank of the gauge group is large, a gravitational description emerges. For the confined phase, we obtain a vector meson spectrum and demonstrate how a certain choice of parameters can lead to quantitative agreement with empirical data. [ABSTRACT FROM AUTHOR]

In particle physics, it is needed to evaluate the possibility that excesses of events in mass spectra are due to statistical fluctuations as quantified by the standards of local and global significances. Without prior knowledge of a particle's mass, it is especially critical to estimate its global significance. The usual approach is to count the number of times a significance limit is exceeded in a collection of simulated Monte Carlo (MC) "toy experiments". To demonstrate this conventional method for global significance, we performed simulation studies according to a recent Compact Muon Solenoid (CMS) result to show its effectiveness. However, this counting method is not practical for computing large global significances. To address this problem, we developed a new "extrapolation" method to evaluate the global significance. We compared the global significance estimated by our new method with that of the conventional approach, and verified its feasibility and effectiveness. This method is also applicable for cases where only small toy MC samples are available. In this approach, the significance is calculated based on p-values, assuming symmetrical Gaussian distributions. [ABSTRACT FROM AUTHOR]

John Bell, with whom I had a fruitful collaboration and warm friendship, is best known for his seminal work on the foundations of quantum physics, but he also made outstanding contributions to particle physics and accelerator physics. [ABSTRACT FROM AUTHOR]

In present-day particle physics, empirical reasoning is highly inferential as experiments rely on complex instruments and an intensive use of computer-based methods. This paper investigates how these methods impact the evidential status of the data produced, using an expanded epistemic risk framework. Based on a case study from a top-quark physics experiment, we clarify the relationship between inductive and other epistemic risks. We argue that various epistemic risks that arise ahead of evidence affect the inductive risk of the experimental results, and propose an understanding of epistemic risk in relation to different epistemic goals. Specifically, the case study shows how experimental tasks and their associated goals relate to the epistemic aim of the experiment, by revealing modalities of risk and risk dynamics throughout the experimental process. [ABSTRACT FROM AUTHOR]

The perturbative treatment of realistic quantum field theories, such as quantum electrodynamics, requires the use of mathematical idealizations in the approximation series for scattering amplitudes. Such mathematical idealizations are necessary to derive empirically relevant models from the theory. Mathematical idealizations can be either controlled or uncontrolled, depending on whether current scientific knowledge can explain whether the effects of the idealization are negligible or not. Drawing upon negative mathematical results in asymptotic analysis (failure of Borel summability) and renormalization group theory (failure of asymptotic safety), we argue that the mathematical idealizations applied in perturbative quantum electrodynamics should be understood as uncontrolled. This, in turn, leads to the problematic conclusion that such theories do not have theoretical models in the natural understanding of this term. The existence of unquestionable empirically successful theories without theoretical models has significant implications both for our understanding of the theory-model relationship in physics and the concept of empirical adequacy. [ABSTRACT FROM AUTHOR]

How was Lattice Gauge Theory born? What was it like in the "early days" of the 1970s and 80s before lattice field theory became a substantial subfield of high energy theory? How did high energy physics and condensed matter theory get together? What were the big physics problems and technical challenges of the day? This short talk looks at these topics from one person's personal recollections, experiences and perspective. [ABSTRACT FROM AUTHOR]

The editorial in "Frontiers in Physics" discusses the challenges and advancements in developing detectors for photon science, focusing on X-ray imaging detectors and sensors. The text highlights the need for detectors to meet the performance increase of new photon sources like Free Electron Lasers and Diffraction-Limited Storage Rings. It also addresses the challenges of data reduction and processing, as well as operational complexities in running imaging systems at photon science facilities. The editorial emphasizes the importance of simplifying system integration and calibration to enhance user interest and data quality in imaging detectors for photon science. [Extracted from the article]

Quantum ChromoDrynamics (QCD) is a quantum field theory, which describes the strong interaction. It explains how quarks and gluons combine to form hadrons. QCD is part of the standard model of particle physics, along with ElectroWeak (EW) theory. The aim of this study is to explore fractional orders in the QCD Lagrangian density using the Atangana–Baleanu fractional derivative. Starting from the fractional Euler–Lagrange equation, we were able to derive the equation of motion of the quark and gluon fields. Then, based on fractional QCD Lagrangian density, the fractional Hamilton equations were obtained. We demonstrate that the principle of local gauge invariance, a fundamental symmetry in QCD, is preserved under a fractional extension of the theory. Our findings indicate that the fractional equations of QCD encompass the classical equations as a specific case, offering a broader perspective on quark-gluon dynamics. The fractional QCD Lagrangian density provides new insights that are not accessible through classical derivatives, potentially enhancing our understanding of quark-gluon plasmas and contributing to advancements in collider phenomenology and precision measurements. This study opens new avenues for exploring the fundamental nature of the strong interaction and its implications for particle physics beyond the Standard Model. [ABSTRACT FROM AUTHOR]