Search

We study a neutrino mass model with A 4 discrete flavor symmetry using a type-I seesaw mechanism. The inclusion of extra flavons in our model leads to deviations from the exact tribimaximal mixing pattern resulting in a nonzero θ 1 3 consistent with the recent experimental results and a sum rule for light neutrino masses is also obtained. In this framework, a connection is established among the neutrino mixing angles-reactor mixing angle ( θ 1 3 ), solar mixing angle ( θ 1 2 ), and atmospheric mixing angle ( θ 2 3 ). This model also allows us a prediction of Dirac CP-phase and Jarlskog parameter (J). The octant of the atmospheric mixing angle θ 2 3 occupies the lower octant. Our model prefers Normal Hierarchy (NH) than Inverted Hierarchy (IH). We use the parameter space of our model of neutrino masses to study the neutrinoless double beta decay parameter m β β . [ABSTRACT FROM AUTHOR]

Dark energy is the largest fraction of the energy density of our universe — yet it remains one of the enduring enigmas of our times. Here we show that dark energy can be used to solve 2 tantalizing mysteries of the observable universe. We build on existing models of dark energy linked to neutrino masses. In these models, dark energy can undergo phase transitions and form black holes. Here we look at the implications of the family structure of neutrinos for the phase transitions in dark energy and associated peaks in black hole formation. It has been previously shown that one of these peaks in black hole formation is associated with the observed peak in quasar formation at redshifts z ∼ 2. 5. Here, we predict that there will also be an earlier peak in the dark energy black holes at high redshifts z ∼ 1 8. These dark energy black holes formed at high redshifts are Intermediate Mass Black Holes (IMBHs). These dark energy black holes at large redshift can help explain both the EDGES observations and the observations of large Supermassive Black Holes (SMBHs) at redshifts of 7 or larger. This work directs us to actively look for these dark energy black holes at these high redshifts as predicted here through targeted searches for these black holes at the redshifts z near 18. There is a slight dependence of the location of the peak on the lightest neutrino mass. This may enable a measurement of the lightest neutrino mass — something which has eluded us so far. Finding these dark energy black holes of Intermediate Mass should be within the reach of upcoming observations — particularly with the James Webb Space Telescope — but perhaps also through the use of other innovative techniques focusing specifically on the redshifts z around 18. [ABSTRACT FROM AUTHOR]

The CDF-II collaboration's recent high-precision measurement of W -boson mass indicates new physics contribution(s) beyond the Standard Model. We investigate the possibility of the well-known canonical Scotogenic model to explain the CDF-II measurement. The Scotogenic model is a popular scenario beyond the Standard Model that induces neutrino masses at the one-loop level and includes a viable dark matter candidate, either scalar or fermionic. For both scalar and fermionic dark matter possibilities, we simultaneously examine the constraints coming from (a) neutrino mass, oscillation, neutrinoless double beta decay and lepton flavor violation experiments, (b) from LEP and LHC, (c) from dark matter relic density and direct detection experiments, (d) from the oblique S , T , U parameter values consistent with CDF-II W -boson measurement. We demonstrate that the new CDF-II measurement rules out the feasible parameter space of the scalar dark matter in the high mass regions ( m η R ≳ 5 0 0 GeV), while still allowing the intermediate mass regions 5 4 GeV ≲ m η R ≲ 7 6 GeV. We also showed that the fermionic dark matter candidate in the canonical Scotogenic model, in the range M N 1 ≲ 5 0 0 GeV , can simultaneously explain all the aforementioned issues. Furthermore, we investigated how the recent findings from ATLAS 2023 impact this study. [ABSTRACT FROM AUTHOR]

The Dirac scotogenic model provides an elegant mechanism which explains small Dirac neutrino masses and neutrino mixing, with a single symmetry simultaneously protecting the "Diracness" of the neutrinos and the stability of the dark matter candidate. Here, we explore the phenomenological implications of the recent CDF-II measurement of the W boson mass in the Dirac scotogenic framework. We show that, in the scenario where the dark matter is mainly a SU (2) L scalar doublet, it can satisfy all the theoretical and experimental constraints along with the CDF-II W boson mass for the mass range of 58–86 GeV. However, unlike the Majorana scotogenic model, the Dirac version also has a "dark sector" SU(2)L singlet scalar. We show that if the singlet scalar is the lightest dark sector particle, i.e. the dark matter then all neutrino physics and dark matter constraints along with the constraints from oblique S, T and U parameters can be concurrently satisfied for W boson mass in the CDF-II mass range, where the singlet dark matter mass is constrained up to around 500 GeV. [ABSTRACT FROM AUTHOR]

Heavy neutrinos are usually introduced to accommodate tiny neutrino masses via seesaw mechanism, or to alleviate the cosmology problem, and there may exist charged Higgs which couple to the leptons with different flavors. These two features can appear in the Twin Higgs models. What interests us is that such new particles and interactions may lead to new contributions to the lepton flavor violating processes ℓ i → ℓ j γ and ℓ i → ℓ j ℓ k ℓ l . We find that current experimental data can constrain the parameter spaces and certain lepton flavor violating processes can possibly be tested by the next generation experiments. [ABSTRACT FROM AUTHOR]

In the framework of anomaly free U (1) L μ − L τ model, singlet scalar field with nonzero L μ − L τ charge gives rise to massive gauge boson (Z μ τ) through spontaneous symmetry breaking. Z μ τ leads to one loop contribution to the muon anomalous magnetic moment. These scalar fields may, also, appear in the structure of right-handed neutrino mass matrix, thus, connecting the possible explanation of muon (g − 2) and low-energy neutrino phenomenology through vevs associated with the scalar fields. In this work, we consider textures of inverse neutrino mass matrix (M ν − 1) wherein any two elements of the mass matrix are zero. In this ansatz, with Dirac neutrino mass matrix diagonal, the zero(s) of right-handed Majorana neutrino mass matrix correspond to zero(s) in the low-energy effective neutrino mass matrix (within Type-I seesaw). We have realized two such textures of M ν − 1 accommodating the muon (g − 2) and low-energy neutrino phenomenology. The requirement of successful explanation of muon (g − 2) , further, constrains the allowed parameter space of the model and results in sharp correlations amongst neutrino mixing angles and CP invariants. The model explains muon (g − 2) for M Z μ τ in the range (0.035–0.100 GeV) and g μ τ ≈ (1 0 − 4) which is found to be consistent with constraints coming from the current experiments CCFR, COHERENT, BABAR while being within sensitivities of future experiments such as NA62 and NA64. [ABSTRACT FROM AUTHOR]

Neutrino flavor mixing is explained within the recently proposed low-scale minimal linear seesaw model of neutrino mass generation, a variant of the standard linear seesaw led by a Dirac pair of extra sterile neutrinos which is odd under a discrete Z 2 symmetry and has a mass at or below the GeV scale. The tri-bimaximal mixing and its deviations are derived straightforwardly on the basis of the symmetry between μ and τ flavors, without introducing non-abelian discrete flavor symmetries in the first place. [ABSTRACT FROM AUTHOR]

We focus on the large width effect on the possibility of excluding or discovering the vector-like bottom quark that is singlet under SU(2) transform at the e − γ collisions. Focusing on the 3 TeV stage of the future Compact Linear Collider (CLIC), the process of single vector-like bottom quark production e − γ → B → b Z t ̄ ν e is investigated. Subsequently, the Z boson decays to one light-flavor lepton pair Z → e + e − (μ + μ −) , and the top quark decay to W boson and bottom quark following with W boson hadronic decay t ̄ → W − b ̄ → b ̄ j j. By launching a comprehensive signal and background collider simulation, we obtain 2 σ exclusion limit and 5 σ discovering prospect based on coupling strength and mass of vector-like quark. We assume the integrated luminosity is 5 ab − 1 . Specially, we take the systemic uncertainty effect on the possibility of excluding or discovering the vector-like bottom quark into account. We find that the excluding irrelated region is g ∗ ∈ [ 0. 2 3 , 0. 5 ] (0. 3 1 , 0. 5) and m B ∈ [ 1 2 0 0 , 1 8 8 0 ] (1 2 0 0 , 1 6 7 0)  GeV, and the discovering irrelated region is g ∗ ∈ [ 0. 3 6 , 0. 5 ] (0. 4 7 , 0. 5) and m B ∈ [ 1 2 0 0 , 1 5 5 0 ] (1 2 0 0 , 1 2 9 0)  GeV in view of the systemic uncertainty δ = 0 (1 0 %). [ABSTRACT FROM AUTHOR]

In this study, a gauge B − L model with Δ (2 7) × Z 4 symmetry is suggested to explain the fermion masses, mixings and hierarchies. We show that the Yukawa couplings in the lepton and quark sectors reach a range only about two orders of magnitude. The smallness of the light neutrino masses, fermion masses and mixings is obtained via the type-I seesaw mechanism. The model is predictive since it can reproduce the realistic lepton and quark mixing patterns, as well as predict the effective neutrino parameters of 〈 m e e 〉 ∈ (3. 8 0 , 4. 2 0) 1 0 − 3  eV and m β ∈ (1. 3 9 , 1. 4 4) 1 0 − 2  eV which are highly consistent with the recent constraints. [ABSTRACT FROM AUTHOR]

Recent studies on swampland conjectures (e.g. non-SUSY AdS conjecture or AdS distance conjecture) predict that the (lightest) neutrino must be Dirac and the mass must be cosmologically small m < c Λ cc 1 / 4 ∼ 1 0 meV. The Dirac neutrino naturally accompanies a U (1) symmetry that can be embedded in the anomaly-free U (1) B − L global symmetry of the standard model. We point out that the swampland conjectures applied to a circle compactification with the U (1) symmetry twisting lead to further constraints. In particular, the U (1) symmetry must be broken down to ℤ 4 , ℤ 8 or ℤ 1 0 in the case of normal hierarchy, and ℤ 4 in the case of inverted hierarchy, providing evidence for the absence of continuous global symmetry in quantum gravity. We also predict a more constrained upper bound of the neutrino mass for each case. [ABSTRACT FROM AUTHOR]

In this paper, we give a brief account of the history of neutrino, and how that most aloof of all particles shaped our search for a theory of fundamental interactions ever since it was theoretically proposed. We introduce the necessary concepts and phenomena in a nontechnical language aimed at a physicist with some basic knowledge of quantum mechanics. In showing that neutrino mass could be the door to new physics beyond the Standard Model, we emphasize the need to frame the issue in the context of a complete theory, with testable predictions accessible to present and near future experiments. We argue in favor of the minimal Left–Right symmetric theory as the strongest candidate for such theory, connecting neutrino mass with parity breakdown in nature. This is the theory that led originally to neutrino mass and the seesaw mechanism behind its smallness, but even more important, the theory that sheds light on a fundamental question that touches us all: the symmetry between left and right. [ABSTRACT FROM AUTHOR]

Measurements of disappearance channel of long baseline accelerator-based experiments (like NO ν A) are inflicted with the problem of octant degeneracy. In these experiments, the mass hierarchy (MH) sensitivity depends upon the value of CP-violating phase δ CP . Moreover, MH of light neutrino masses is still not fixed. Also, the flavor structure of fermions is yet not fully understood. We discuss all these issues in a highly predictive, low-scale inverse seesaw (ISS) model within the framework of A 4 flavor symmetry. Recent global analysis has shown a preference for normal hierarchy and higher octant of 2 3 , and hence we discuss our results with reference to these, and find that the vacuum alignment of A 4 triplet flavon (1 , − 1 , − 1) favors these results. Finally, we check if our very precise prediction on m e e and the lightest neutrino mass falls within the range of sensitivities of the neutrinoless double beta decay (0 ν β β) experiments. We note that when octant of 2 3 and MH is fixed by more precise measurements of future experiments, then through our results, it would be possible to precisely identify the favorable vacuum alignment corresponding to the A 4 triplet field as predicted in our model. [ABSTRACT FROM AUTHOR]

In this paper, we update the standard model d = 6 operators of Weinberg (1979) using a modified notation which accommodates the bilepton extension of the standard model. This may lead to an enhancement of the proton lifetime by orders of magnitude due to mixing first-family with third-family quarks. By contrast, d = 5 operators which can provide Majorana neutrino masses retain the family structure of their counterparts in the standard model. [ABSTRACT FROM AUTHOR]

The upcoming upgrades of Large Hadron Collider (LHC) to High Luminosity LHC (HL-LHC) and the proposed Future Circular Collider (FCC-hh) offer an opportunity of observing the Lepton Flavor Violating (LFV) process beyond the Standard Model. Monte Carlo simulation of generating and detecting an LFV process B + → K + μ − τ + on CMS at LHC (Run-3), HL-LHC, and FCC-hh reference detector (FRD) is performed. This process is favored by the leptoquark models, particularly the three-site Pati–Salam model but disfavored by the gauged L μ − L τ model, both of which are introduced to address the B anomalies. We study possible backgrounds with similar final states and use Multi-Variable Analysis (MVA) to discriminate signal events from possible backgrounds. The MVA output is used to estimate Single Event Sensitivity (SES) of this process, yielding encouraging results on CMS at HL-LHC and FRD at FCC-hh with considerable SES values of about 0. 0 6 9 6 ± 0. 0 0 1 0 fb (CMS, LHC Run-3), 0. 0 0 7 0 ± 0. 0 0 0 1 fb (CMS, HL-LHC) and 0. 1 3 8 9 ± 0. 0 0 0 6 ab (FRD, FCC-hh), suggesting it's promising to probe such process in the future high energy physics experiments and constrain the new physics models more rigorously. [ABSTRACT FROM AUTHOR]

Violation of equivalence principle predicts that neutrinos of different flavor couple differently with gravity. Such a scenario can give rise to gravity induced flavor oscillations in addition to the usual mass flavor neutrino oscillations during the neutrino propagation. Even if the equivalence principle is indeed violated, their measure will be extremely small. We explore the possibility to probe the violation of equivalence principle (VEP) for the case of long baseline (LBL) neutrinos in a 4-flavor neutrino framework (3 active + 1 sterile) where both mass and gravity induced oscillations are considered. To this end, we have explicitly calculated the oscillation probability in 4-flavor framework that includes in addition to the mass-flavor mixing in matter, the gravity-flavor mixing also. The energy eigenvalues are then obtained by diagonalizing such a 4-flavor mixing matrix. The formalism is then employed to estimate the wrong and right sign muon yields at a far detector for neutrinos produced in a neutrino factory and travel through the Earth matter. These results are compared with the similar estimations when the usual three active neutrinos are considered. [ABSTRACT FROM AUTHOR]

Uncertainties in flavor and mass eigenstates of neutrinos are considered within the majorization approach. Nontrivial bounds reflect the fact that neutrinos cannot be simultaneously in flavor and mass eigenstates. As quantitative measures of uncertainties, both the Rényi and Tsallis entropies are utilized. Within the current amount of experience concerning the mixing matrix, majorization uncertainty relations need to put values of only two parameters, viz. 1 2 and 1 3 . That is, the majorization approach is applicable within the same framework as the Maassen–Uffink relation recently utilized in this context. We also consider the case of detection inefficiencies, since it can naturally be incorporated into the entropic framework. Short comments on applications of entropic uncertainty relations with quantum memory are given. [ABSTRACT FROM AUTHOR]

In this paper, we study a non-renormalizable U (1) B − L extension of the Standard Model with D 4 and Z 4 symmetries accommodating the most recent neutrino data within the type-I seesaw mechanism. The two squared mass differences and three mixing angles can get the best-fit values while the leptonic Dirac CP phase is in 1 σ range of the best-fit values for both normal and inverted orderings. The sum of active neutrino mass and the effective neutrino masses are, respectively, predicted to be ∑ m ν = 6 0. 0 3 meV , 〈 m e e 〉 = 2. 3 0 7 meV and 〈 m β 〉 = 8. 9 0 3 meV for normal ordering while ∑ m ν = 1 0 1. 2 0 meV , 〈 m e e 〉 = 4 9. 9 3 meV and 〈 m β 〉 = 4 9. 9 5 meV for inverted ordering, which are well consistent with the current experimental constraints. [ABSTRACT FROM AUTHOR]

We consider an extension of the Standard Model with three right-handed (RH) neutrinos and a Dirac pair of extra sterile neutrinos, odd under a discrete Z 2 symmetry, in order to have left–right symmetry in the neutrino content and obtain tiny neutrino masses from the latter ones only. Our working hypothesis is that the heavy RH neutrinos do not influence phenomenology at low energies. We use the usual high-scale seesaw to suppress all of the mass terms involving RH neutrinos and a low-scale minimal variant of the linear seesaw led by the Dirac mass of the extra sterile neutrinos to provide the small mass of active neutrinos. One of the active neutrinos is massless, which fixes the mass of the other two on the basis of a soft breaking of the Z 2 symmetry. The mixing between the extra neutrinos makes for a particle that effectively behaves like a Dirac sterile neutrino with mass around the GeV level. [ABSTRACT FROM AUTHOR]

We construct a non-renormalizable B − L model based on Σ (1 8) symmetry, whereby, neutrino mass ordering and the tiny neutrino masses are explained at tree level via type I seesaw mechanism. The model can reproduce the recent observed neutrino oscillation data in which neutrino oscillation parameters including three mixing angles 𝜃 1 2 , 2 3 , 1 3 , Dirac CP phase plus neutrino squared-mass splittings Δ m 2 1 , 3 2 get the best-fit values for both Normal ordering (NO) and Inverted ordering (IO). The Majorana phases are predicted to be α = 0 for NO, α = π for IO and β = 0. 8 6 π for both NH and IO. The sum of neutrino mass and the effective neutrino mass are, respectively, predicted to be ∑ m ν = 0. 0 5 9 eV for NO while ∑ m ν = 0. 1 0 0 2 eV for IO and 〈 m e e 〉 = 1. 5 1 meV for NO while 〈 m e e 〉 = 4 8. 8 meV for IO which are well compatible with the most recent experimental constraints. [ABSTRACT FROM AUTHOR]

The neutrino oscillation probabilities at the long-baseline accelerator neutrino experiments are expected to be modified by matter effects. We search for evidence of such modification in the data of T2K and NO ν A, by fitting the data to the hypothesis of (a) matter modified oscillations and (b) vacuum oscillations. We find that vacuum oscillations provide as good a fit to the data as matter modified oscillations. Even extended runs of T2K and NO ν A, with five years in neutrino mode (5 ν) and five years in anti-neutrino mode (5 ν ̄) , cannot make a 3 σ distinction between vacuum and matter modified oscillations. The future experiment DUNE, with neutrino and anti-neutrino runs of five years each (5 ν + 5 ν ̄) , can rule out vacuum oscillations by itself at 5 σ if the hierarchy is normal. If the hierarchy is inverted, a 5 σ discrimination against vacuum oscillations requires the combination of (5 ν + 5 ν ̄) runs of T2K, NO ν A and DUNE. [ABSTRACT FROM AUTHOR]

We investigate and quantify bipartite and tripartite entanglement measures in two- and three-flavor neutrino oscillations. The bipartite entanglement is analogous to the entanglement swapping resulting from a beam splitter in quantum optics. We calculate various entanglement measures, such as the concurrence, negativity, and three-tangle for the three-neutrino system. The significant result is that a monogamy inequality in terms of negativity leads to a residual entanglement, implying genuine tripartite entanglement in the three-neutrino system. We establish an analogy of the three-neutrino state with a generalized W-state class in quantum optics. [ABSTRACT FROM AUTHOR]

We propose a renormalizable gauge U (1) B − L extension of the Standard Model (SM) based on Q 4 symmetry and an auxiliary Z 4 symmetry which can explain the observed quark and lepton masses and mixing angles associated to normal neutrino mass ordering through type-I seesaw mechanism. The relation between the atmospheric mixing angle 𝜃 2 3 and the effective parameters in neutrino sector is analyzed. Two Majorana phases are predicted to be α 2 1 = 0 and α 3 1 = − 1. 9 3 8 5 rad and the model also predicts the effective neutrino mass parameters of m β = 6. 6 8 5 meV , 〈 m e e 〉 = 6. 7 6 7 meV which is well consistent with the planning of future experiments. In the quark sector, the model is predictive since it has ten effective parameters that allow to successfully reproduce the experimental values of the experimental values of the ten physical observables of the quark sector. [ABSTRACT FROM AUTHOR]

We propose a renormalizable U (1) B − L extension of the Standard model with A 4 symmetry that leads to the successful cobimaximal lepton mixing ansatz, thus providing a predictive explanation for leptonic mixing observables. The smallness of the active neutrino masses and neutrino masses ordering are produced by the type-I seesaw mechanism at the tree-level. The obtained physical parameters are well consistent with the global fit of neutrino oscillation.1 The model is predictive in the sense that it reproduces the experimental values of neutrino parameters in which the reactor neutrino mixing angle 𝜃 1 3 get the best-fit value and the solar and atmospheric neutrino mixing angles have little deviations from the best-fit values given in Ref. 1, however, they are consistent with the other experimental results. 3 , 4 The effective neutrino masses governing the neutrinoless double beta decay is predicted to be 〈 m e e 〉 = 8. 2 5 × 1 0 − 3 eV for normal hierarchy and 〈 m e e 〉 = 4. 9 2 × 1 0 − 2 eV for inverted hierarchy which are well consistent with the recent experimental limits on neutrinoless double beta decay. [ABSTRACT FROM AUTHOR]

Asymmetric tri-bi-maximal mixing is a recently proposed, grand unified theory (GUT) based, flavor mixing scheme. In it, the charged lepton mixing is fixed by the GUT connection to down-type quarks and a 𝒯 1 3 flavor symmetry, while neutrino mixing is assumed to be tri-bi-maximal (TBM) with one additional free phase. Here we show that this additional free phase can be fixed by the residual flavor and CP symmetries of the effective neutrino mass matrix. We discuss how those residual symmetries can be unified with 𝒯 1 3 and identify the smallest possible unified flavor symmetries, namely (ℤ 1 3 × ℤ 1 3) ⋊ D 1 2 and (ℤ 1 3 × ℤ 1 3) ⋊ S 4 . Sharp predictions are obtained for lepton mixing angles, CP violating phases and neutrinoless double beta decay. [ABSTRACT FROM AUTHOR]

In this work, we suggest a renormalizable U (1) B − L extension of the Standard Model with Σ (1 8) symmetry in which the observed fermion mass and mixing pattern is consistent with the experimental values given in Ref. 1 at the tree-level. The neutrino mass ordering and the tiny neutrino masses are induced by the type-I seesaw mechanism. The effective neutrino mass parameters are predicted to be 〈 m e e 〉 = 1. 5 1 × 1 0 − 3 eV , m β = 8. 8 1 × 1 0 − 3 eV for NO and 〈 m e e 〉 = 4. 8 9 × 1 0 − 2 eV , m β = 4. 9 4 × 1 0 − 2 eV for IO which are well consistent with the recent experimental data. The quark masses are in good agreement while the quark mixing matrix has a little difference with the experimental data taken from Ref. 1 and the Cabibbo angle 𝜃 C is related to the model parameter γ by the formula sin 2 γ = sin 𝜃 C ≈ 0. 2 2 4 5. [ABSTRACT FROM AUTHOR]

A machine learning method is applied to analyze lepton mass matrices numerically. The matrices were obtained within a framework of high-scale supersymmetry (SUSY) and a flavor symmetry, which are too complicated to be solved analytically. In this numerical calculation, the heuristic method in machine learning is adopted. Neutrino masses, mixings, and CP violation are obtained. It is found that neutrinos are normally ordered and the favorable effective Majorana mass is about 7 × 1 0 − 3 eV. [ABSTRACT FROM AUTHOR]

We propose a B − L Standard Model (SM) extension based on Δ (2 7) symmetry in which neutrino mass orderings and the tiny neutrino masses are produced by the type-I seesaw mechanism. The obtained physical parameters are well consistent with the global fit of neutrino oscillation.1 The model is predictive in the sense that it reproduces the experimental values of neutrino parameters. Two of the predicted parameters have little deviations from the best-fit values given in Ref. 1, however they are consistent with the other experimental results. 2 , 3 [ABSTRACT FROM AUTHOR]

We show that a very simple solution to the strong CP problem naturally leads to Dirac neutrinos. Small effective neutrino masses emerge from a type-I Dirac seesaw mechanism. Neutrino mass limits probe the axion parameters in regions currently inaccessible to conventional searches. [ABSTRACT FROM AUTHOR]

We have investigated the phenomenological implications of texture one-zero neutrino mass matrix under the lamp post of the latest data on neutrino mass and mixings. In particular, we have obtained the predictions of the model for, yet unknown observables like neutrino mass hierarchy, 𝜃 2 3 -octant and CP violation. Out of the six texture one-zero neutrino mass models, T 1 , T 2 and T 3 are found to be necessarily CP violating. 𝜃 2 3 can be above or below maximality except for the texture T 4 (with NH), wherein 𝜃 2 3 < 4 5 ∘ at 2. 5 σ. Also, we have proposed a flavor model based on the non-Abelian group A 4 within the paradigm of type-I+II seesaw framework, wherein such textures can be realized. [ABSTRACT FROM AUTHOR]

I reflect on some of the basic aspects of present day Beyond the Standard Model particle physics, focusing mostly on the issues of naturalness, in particular on the so-called hierarchy problem. To all of us, physics as natural science emerged with Galileo and Newton, and led to centuries of unparalleled success in explaining and often predicting new phenomena of nature. I argue here that the long-standing obsession with the hierarchy problem as a guiding principle for the future of our field has had the tragic consequence of deviating high energy physics from its origins as natural philosophy, and turning it into a philosophy of naturalness. [ABSTRACT FROM AUTHOR]

One of the remaining undetermined fundamental aspects in neutrino physics is the determination of the neutrino mass hierarchy, i.e. discriminating between the two possible orderings of the mass eigenvalues, known as Normal and Inverted Hierarchies. The Jiangmen Underground Neutrino Observatory (JUNO), a 20 kt Liquid Scintillator Detector currently under construction in the South of China, can determine the neutrino mass hierarchy and improve the precision of three oscillation parameters by one order of magnitude. Moreover, thanks to its large liquid scintillator mass, JUNO will also contribute to study neutrinos from non-reactor sources such as solar neutrinos, atmospheric neutrinos, geoneutrinos, supernova burst and diffuse supernova neutrinos. Furthermore, JUNO will also contribute to nucleon decay studies. In this work, I will describe the status and the perspectives of the JUNO experiment. [ABSTRACT FROM AUTHOR]

The long baseline neutrino experiments, T2K and NO ν A, have taken significant amount of data in each of the four channels: (a) ν μ disappearance, (b) ν ̄ μ disappearance, (c) ν e appearance, and (d) ν ̄ e appearance. There is a mild tension between the disappearance and the appearance data sets of T2K. A more serious tension exists between the ν e appearance data of T2K and the ν e / ν ̄ e appearance data of NO ν A. This tension is significant enough that T2K rules out the best-fit point of NO ν A at 95% confidence level, whereas, NO ν A rules out T2K best-fit point at 90% confidence level. We explain the reason why these tensions arise. We also do a combined fit of T2K and NO ν A data and comment on the results of this fit. [ABSTRACT FROM AUTHOR]

In this paper, we perform a comparative analysis between the future proposed long-baseline experiments ESSnuSB and T2HK in measuring the leptonic CP phase δ CP . In particular, we study the effect of the neutrino mass ordering degeneracy and the leptonic mixing angle 𝜃 2 3 octant degeneracy in the measurement of leptonic CP violation and precision for both experiments. Since the ESSnuSB (T2HK) experiment probes the second (first) oscillation maximum to study neutrino oscillations, the effect of these degeneracies are significantly different in both experiments. Our main conclusion is that for the ESSnuSB experiment, the information on the neutrino mass ordering does not play a major role in the determination of δ CP , which is not the case for the T2HK experiment. However, the information on the true octant compromises the CP sensitivity of the ESSnuSB experiment as compared to T2HK if 𝜃 2 3 lies in the lower octant. These conclusions are true for both the 540 km and 360 km baseline options for the ESSnuSB experiment. In addition, we investigate the effect of different running times in neutrino and antineutrino modes and the effect of 𝜃 2 3 precision in measuring δ CP . [ABSTRACT FROM AUTHOR]

We suggest a renormalizable standard model (SM) extension based on D 5 symmetry which accommodates leptonic mass and mixing parameters with nonzero 𝜃 1 3 and Dirac CP violating phase. Both normal and inverted neutrino mass ordering as well as the smallness of the active neutrino masses are generated at leading order through type-I seesaw mechanism in which the obtained physical parameters are well consistent with the global fit of neutrino oscillation data [P. F. de Salas et al., Phys. Lett. B 782, 633 (2018)], while the quark masses are in good agreement with the recent experimental data [Particle Data Group (M. Tanabashi et al.), Phys. Rev. D 98, 030001 (2018)]. The model also predicts an effective Majorana neutrino mass parameter of m β β = 8. 8 1 1 2 3 × 1 0 − 2 eV for normal hierarchy and m β β = 4. 9 0 8 6 2 × 1 0 − 2 eV for inverted hierarchy which are all well below the most current upper limit given [P. F. de Salas et al., Front. Astron. Space Sci. 5, 36 (2018); CUORE Collab. (C. Alduino et al.), Phys. Rev. Lett. 120, 132501 (2018)] and beyond the reach of the present 0 ν β β decay experiments. [ABSTRACT FROM AUTHOR]

Neutrino matter and the quintessence field interacting with a fermion field are added to a MSSM EW Lagrangian previously used to calculate the magnetic field created during the Electroweak Phase Transition (EWPT). Flavor neutrinos are linear combinations of neutrinos with a definite mass. We estimate the mass of neutrinos using the value of the quintessence field during the EWPT with a modification of parameters used in a previous work on Dark Matter–Dark Energy interactions for a weak neutrino interaction. The possibility that sterile neutrinos might be Dark Matter is briefly reviewed. [ABSTRACT FROM AUTHOR]

The minimal seesaw framework, embroiling the Dirac neutrino mass matrix M D and the Majorana neutrino mass matrix M R , is quite successful to explain the current global-fit results of neutrino oscillation data. In this context, we consider the most predictive forms of M D and M R with two simple parameters, respectively. Considering these matrices, we obtain the low-energy neutrino mass matrix under type-I seesaw formalism which obeys μ − τ reflection symmetry and predicts 𝜃 2 3 = π / 4 and δ = ± π / 2. In the given set-up, we also evaluate the Baryon Asymmetry of the Universe (BAU) through successful leptogenesis and find that perturbation of 𝒪 (1 0 − 2) leads to the observed BAU and breaks exactness of the symmetry. Moreover, we also perform various correlation studies among different parameters in the framework of broken symmetry. [ABSTRACT FROM AUTHOR]

The existence and mysterious nature of sterile neutrinos are revolutionizing physics from the particle level to the cosmological scales. The recent results from the MiniBooNE experiment at Fermi-lab observed far more ν e appearance than expected, which have provided a hint about the possible existence of sterile neutrinos. The results, if confirmed in future experiments, will have significant implications for cosmology and astroparticle physics. This will require new neutrino mass models to accommodate these additional degrees of freedom. In respect to that, this work is just an extension of our recent work toward the CP phase analysis of Quark-Lepton Complementarity (QLC) model in a 3 + 1 scenario. The parametrization of CKM4 and PMNS4 using Monte Carlo Simulation is used to estimate the texture of nontrivial correlation matrix (V c 4 ). As such, we have successfully investigated the constrained values for sterile neutrino parameters, and also predicted the values for Dirac CP-Violation phase and the CP re-phasing invariant (J). The results obtained are consistent with the data available from various experiments, like No ν A, MINOS, SuperK and IceCube-DeepCore. Furthermore, this analysis would be very important in view of growing sterile neutrino experiments. [ABSTRACT FROM AUTHOR]

The Standard Model (SM) with one right-handed neutrino per generation is revisited with presymmetry being the global U (1) B − L symmetry of an electroweak theory of leptons and quarks with initially postulated symmetric fractional charges. The cancellation of gauge anomalies and the non-perturbative normalization of lepton charges proceed through the mixing of local and topological charges, the global B − L measuring the induced charge associated with a unit of topological charge, and the mathematical replacement of the original fractional charges with the experimentally observed ones. The U (1) B − L symmetry of the SM with Dirac neutrinos is seen as a residual presymmetry. High-scale and low-scale seesaw mechanisms proposed to explain the mass of neutrinos are examined from the perspective of presymmetry, be they of Majorana or pseudo-Dirac type. We find that the tiny mass splitting in pseudo-Dirac neutrinos and the mass of heavy neutrinos ride on the opposite ends of the seesaw. We show that pseudo-Dirac neutrinos contain extra sterile neutrinos with imprints of presymmetry and for heavy ones we get constraints favoring the low-scale linear seesaw over the inverse variant. [ABSTRACT FROM AUTHOR]

We construct a renormalizable SU (3) C ⊗ SU (3) L ⊗ U (1) X ⊗ U (1) ℒ model with Q 4 symmetry accommodating the observed pattern of fermion masses and mixings with Dirac CP violation phase. The smallness of the active neutrino masses arises from a combination of type I and type II seesaw mechanisms. Both normal and inverted neutrino mass ordering are viable in our model in which the obtained physical observables of the lepton sector are well consistent with the global fit of neutrino oscillation data [P. F. de Salas et al., Phys. Lett. B 782, 633 (2018)] while the CKM matrix is unity at tree level and the quark masses are in good agreement with the experimental data [Particle Data Group (M. Tanabashi et al.), Phys. Rev. D 98, 030001 (2018)]. Furthermore, the model also predicts an effective Majorana neutrino mass parameter of m β β = 3. 3 8 4 4 9 × 1 0 − 3 eV for normal hierarchy and m β β = 4. 9 4 6 7 9 × 1 0 − 2 for inverted hierarchy which are consistent with the constraints given in [P. F. de Salas et al., Phys. Lett. B 782, 633 (2018)]. [ABSTRACT FROM AUTHOR]

In this paper, we will consider a cosmological model with two topological transitions of the space. The smooth 4-dimensional spacetime of the model admits topological transitions of its 3-dimensional slices. The whole approach is inspired by a class of exotic smoothness structures on S 3 × ℝ. In particular, this class of smoothness structures induces two topological transitions. Then, we are able to calculate the energy scales as associated to these topological transitions. For the first transition we will get the value of the GUT scale and the energy of the second transition is at the electroweak scale. The topology of the exotic S 3 × ℝ determines both, the energy of the scales by certain topological invariants, and the existence of the right-handed sterile neutrino. It is the input for the seesaw mechanism. Secondly, based on this model, we are able to calculate the neutrino masses which are in a very good agreement with experiments. Finally, we will speculate, again based on topology, why there are three generations of neutrinos and an asymmetry between neutrinos and anti-neutrinos. [ABSTRACT FROM AUTHOR]

We analyze the one-loop correction to Z → ν ν decay in framework of Minimal R-symmetric Supersymmetric Standard Model (MRSSM) in detail with normal and inverse neutrino mass orderings, as a function of tan β , Dirac mass parameters M D W and μ u (μ d) , slepton mass m l that parametrize the mass matrices. The numerical results indicate that the branching ratio for Z → ν ν decay is compatible with the experimental measurement and the SM expectation at 2 σ level. For inverse neutrino mass ordering, the prediction exceeds the SM expectation at 1 σ level. The prediction on Br (Z → ν ν) increases proportionally to tan β and inversely proportionally to m l . For normal neutrino mass ordering, the peak value of the prediction on Br (Z → ν ν) exceeds the SM expectation at 1 σ level. [ABSTRACT FROM AUTHOR]

We propose a renormalizable T′ flavor model based on the SU (3) C × SU (3) L × U (1) X × U (1) ℒ gauge symmetry, consistent with the observed pattern of lepton masses and mixings. The small masses of the light active neutrinos are produced from an interplay of type I and type II seesaw mechanisms, which are induced by three heavy right-handed Majorana neutrinos and three SU (3) L scalar antisextets, respectively. Our model is only viable for the scenario of normal neutrino mass hierarchy, where the obtained physical observables of the lepton sector are highly consistent with the current neutrino oscillation experimental data. In addition, our model also predicts an effective Majorana neutrino mass parameter of m β ∼ 1. 4 1 5 4 1 × 1 0 − 2  eV, a Jarlskog invariant of the order of J CP ∼ − 0. 0 3 2 and a leptonic Dirac CP violating phase of δ = 2 3 8 ∘ , which is inside the 1 σ experimentally allowed range. [ABSTRACT FROM AUTHOR]

Recently, we have proposed a quark mass matrix model based on U(3) × U(3) ′ family symmetry, in which up- and down-quark mass matrices M u and M d are described only by complex parameters a u and a d , respectively. When we use charged lepton masses as additional input values, we can successfully obtain predictions for quark masses and Cabibbo–Kobayashi–Maskawa mixing. Since we have only one complex parameter a q for each mass matrix M q , we can obtain a parameter-independent mass relation by using three equations for Tr [ H q ] , Tr [ H q H q ] and det H q , where H q ≡ M q M q † (q = u , d). In this paper, we investigate the parameter-independent feature of the quark mass relation in the model. [ABSTRACT FROM AUTHOR]

The neutrino masses can be ascribed to some operators of higher dimension than the Weinberg operator, so that the energy scale of underlying theory can be lowered to an accessible level for the ongoing or upcoming colliders. We hereby consider an interesting model in this connection where quintuplet fermions with hypercharge − 2 are introduced and therefore the neutrino masses are produced by dimension-11 operators. These exotic fermions can be pairly produced at the LHC via electroweak interactions and subsequently decay to multiple leptons. We simulate the relevant signal and backgrounds of the triply charged fermion in this model, and give the needed integrated luminosity to observe such a particle at the 13 TeV LHC. [ABSTRACT FROM AUTHOR]

Alternative renormalizable minimal non-SUSY SO(10) GUT model is proposed. Instead of a 126-dimensional Higgs field, a 120-dimensional Higgs filed is introduced in addition to a 10-dimensional Higgs field and plays a crucial role to reproduce the realistic charged fermion mass matrices. With contributions of 120 Higgs field, the original Witten's scenario of inducing the right-handed Majorana neutrino mass through 2-loop diagrams becomes phenomenologically viable. This model inherits the nice features of the conventional renormalizable minimal SO(10) GUT model with 1 0 + 1 2 6 ¯ Higgs fields, while supplemented with a low scale seesaw mechanism due to the 2-loop induced right-handed Majorana neutrino mass. [ABSTRACT FROM AUTHOR]

The well-known leptonic U(1) symmetry of the Standard Model (SM) of quarks and leptons is extended to include a number of new fermions and scalars. The resulting theory has an invisible QCD axion (thereby solving the strong CP problem), a candidate for weak-scale dark matter (DM), as well as radiative neutrino masses. A possible key connection is a color-triplet scalar, which may be produced and detected at the Large Hadron Collider. [ABSTRACT FROM AUTHOR]

A brief review is given of some recent works where baryogenesis and dark matter have a common origin within the U(1) extensions of the Standard Model (SM) and of the minimal supersymmetric Standard Model (MSSM). The models considered generate the desired baryon asymmetry and the dark matter to baryon ratio. In one model, all of the fundamental interactions do not violate lepton number, and the total in the Universe vanishes. In addition, one may also generate a normal hierarchy of neutrino masses and mixings in conformity with the current data. Specifically, one can accommodate consistent with the data from Daya Bay reactor neutrino experiment. [ABSTRACT FROM AUTHOR]

We give some new insights into the effective Majorana neutrino mass responsible for the neutrinoless double-beta decays. We put forward a three-dimensional way of plotting against the lightest neutrino mass and the Majorana phases, which can provide more information as compared with the two-dimensional one. With the help of such graphs we discover a novel threshold of in terms of the neutrino masses and flavor mixing angles: in connection with and , which can be used to signify observability of the future -decay experiments. Fortunately, the possibility of turns out to be very small, promising a hopeful prospect for the -decay searches. [ABSTRACT FROM AUTHOR]

In collaboration with Jogesh Pati, Abdus Salam challenged the chiral gauge nature of the Standard Model by paving the road towards the left-right symmetric electro-weak theory. I describe here the logical and historical construction of this theory, by emphasising the pioneering and key role it played for neutrino mass. I show that it is a self-contained and predictive model with the Higgs origin of Majorana neutrino mass, in complete analogy with the SM situation regarding charged fermions. [ABSTRACT FROM AUTHOR]

We propose an extension of the Standard Model of quarks and leptons to include gauge B- L symmetry with an exotic array of neutral fermion singlets for anomaly cancellation. With the addition of suitable scalars also transforming under U(1), this becomes a model of radiative seesaw neutrino mass with possible multipartite dark matter. If leptoquark fermions are added, necessarily also transforming under U(1), the diphoton excess at 750 GeV, recently observed at the Large Hadron Collider, may also be explained. [ABSTRACT FROM AUTHOR]