Breaking Effects Research Articles

Explaining the CDF-II W-boson mass anomaly in the Georgi–Machacek extension models

Original Georgi–Machacek model can preserve the custodial symmetry at tree level after the electroweak symmetry breaking. Unless additional SU(2)_c custodial symmetry breaking effects are significant, the new physics contributions to Delta m_W are always very small. Our numerical results show that ordinary GM model can contribute to Delta m_W a maximal amount 0.0012 GeV, which can not explain the new CDF-II anomaly on W boson mass. We propose firstly to introduce small misalignment among the triplet VEVs to increase Delta m_W, which can give large new physics contributions to Delta m_W. Such slightly misaligned triplet VEVs from custodial symmetry preserving scalar potential can still be allowed. Our numerical results indicate that the resulting Delta m_W can easily reach the 1sigma range of CDF-II m_W data and the splitting among the triplet VEVs Delta v(equiv v_xi -v_chi ) can be as small as 0.8 GeV for v_chi lesssim 15 GeV. We also propose to introduce an additional custodial symmetry breaking source by extending the GM model with a low scale RH neutrino sector, which can adopt the leptogenesis mechanism and allow moderately large coupling strength h_{ij} even for triplet VEVs of order GeV. With low scale RH neutrino mass scale of order 10^2–10^4 TeV, the new physics contribution to Delta m_W can reach 0.03 GeV and is much larger than that of ordinary GM model. Combining both custodial SU(2)_c symmetry breaking effects, the small misalignment among the triplet VEVs and the moderately large h_{ij} couplings allowed with RH neutrino sector, the value of Delta m_W can still easily reach the 1sigma range of CDF-II m_W data, with a minimum splitting (among the triplet VEVs) approximately 0.7 GeV for v_chi lesssim 15 GeV.

Can proactively confessing obtain your embrace? Exploring for leader's pro-social rule-breaking consequences based on a self-verification perspective.

The effect of leader pro-social rule breaking on employees is a critical albeit underexplored topic within the domain of study on the consequences of pro-social rule breaking in organizations. This study attempts to make up for the gap by exploring the relationship between leader pro-social rule breaking and employee voice. Drawing on the theory of self-verification, we theorize that leaders who perform pro-social rule breaking will seek feedback from their subordinates, while employees being sought will be triggered to voice upwardly, the extent to which intensity of voice is moderated by the moral courage of employees. A total of 283 dyads data of supervisor-subordinate from Shanghai, China, in a three-wave time-lagged survey provided support for our hypotheses. The results show that leader pro-social rule breaking is positively related to leader feedback-seeking, which is positively related to employee upward voice and mediates the relationship between the two. Moreover, the positive relationship between leader pro-social rule breaking and leader feedback-seeking as well as the indirect effect of leader pro-social rule breaking on employee upward voice via leader feedback-seeking was weakened when moral courage is high. The present study promotes the theoretical research on the positive results of leader pro-social rule breaking and also suggests that feedback-seeking would be an effective way for leaders to motivate employees' upward voice.

A novel solution to the gravitino problem

In a general phenomenological model with local supersymmetry, the amount of massive gravitinos produced in early universe tends to violate the known dark matter density bound by many orders of magnitude. In the brane world scenario in Type IIB string theory, we propose a novel way to evade this problem. There, the standard model of strong and electroweak interactions live inside the anti-D3-branes ( overline{textrm{D}3} -branes) that span the 3 large spatial dimensions. Here, the “potential” Goldstino to be absorbed by the gravitino (to become massive) is the fermion component of the open string nilpotent superfield X (i.e., X2 = 0) which is present only inside the overline{textrm{D}3} -branes. This non-linear supergravity scenario offers 2 ways to solve the gravitino problem, with very different particle physics phenomenologies: (1) To satisfy the necessary condition for a naturally small cosmological constant Λ, the supersymmetry breaking overline{textrm{D}3} -branes tension is precisely cancelled by the Higgs spontaneous symmetry breaking effect, so the gravitino is ultra-light and its contribution to the dark matter density is negligible. If exist, the super-particles should have already been detected in experiments. To avoid contradiction with their non-observation, X is applied to project out all the “R-parity odd” fields. Consequently, this non-linear supergravity model is almost identical to the standard model. (2) As an alternative, one can have a massive gravitino (e.g., {hat{m}}_{3/2} > 100 GeV) due to the supersymmetry breaking tension of the overline{textrm{D}3} -branes. Here, the super-particles can be heavy enough to have avoided detection so far. Since the open string Goldstino exists only inside the overline{textrm{D}3} -branes, the gravitino is heavy only inside the overline{textrm{D}3} -branes, but massless or ultra-light outside the overline{textrm{D}3} -branes. This means that the gravitinos will be pushed out of the overline{textrm{D}3} -branes to the extra dimensions in the bulk, a phenomenon analogous to the Meissner effect for the massive photons inside super-conductors but massless outside. As a result, the massive gravitinos will be depleted so the gravitino problem is absent. In this case, a fine-tuning is necessary to obtain the very small observed Λobs.

Resolving puzzle in [formula omitted] with [formula omitted] mixing spectrum within the quark model

We study the ratio of R=2Γ(Ξc0→Ξ−e+νe)/3Γ(Λc+→Λe+νe), which is found to be R=1(0.8) from the exact (broken) SU(3) flavor symmetry, in sharp contrast to the average value of Rav=0.59±0.10 from the ALICE collaboration and lattice QCD results. We propose to use the mixing of Ξc−Ξc′ to resolve the puzzle. From the mass spectra, we find that the mixing angle is |θc|=0.137(5)π, which suppresses Ξc→Ξe+νe about 20% model-independently, resulting in R≈0.6 with the SU(3) flavor breaking effect. We explicitly demonstrate that R=0.70±0.09 from the bag model, which is also consistent with Rav. To test the mixing mechanism, we recommend the experiments to measure the decays of Ξc→Ξ′(1530)e+νe, whose branching fractions are determined to be (4.4∼8.7)×10−3 and (1.3∼2.6)% for Ξc0 and Ξc+, respectively, but vanish without the mixing. In addition, nonvanishing values of B(Ξc+→Ξ′0(1530)π+) and B(Ξc+→Σ′+(1385)K‾0) will also be evidences of the mixing based on the Körner-Pati-Woo theorem, which are calculated as (3.8∼7.5)×10−3 and (6.6∼13)×10−4, respectively. We emphasize that θc is sizable and should be given serious considerations in future studies on the heavy baryon systems.

A Low‐Concentration and High Ionic Conductivity Aqueous Electrolyte toward Ultralow‐Temperature Zinc‐Ion Hybrid Capacitors

Aqueous electrochemical energy storage devices have attracted tremendous attention because of its high safety, low cost, and environmental friendliness. However, their low‐temperature operation is plagued by the freeze of electrolytes. Herein, a 3 mol kg−1 Zn(ClO4)2 electrolyte without adding any organic solvents or antifreezing additives is proposed, which yields a high ionic conductivity of 9.4 mS cm−1 even at ultralow temperatures of −60 °C. The strong electrostatic interaction between Zn2+ ion and water molecules and the structure breaking effect of ClO4− ions to destroy the hydrogen bond network between water molecules in Zn(ClO4)2 electrolyte is revealed by spectroscopic characterization and theoretical simulation. This low‐temperature electrolyte renders the zinc‐ion hybrid capacitor to exhibit a high energy density of 40.91 Wh kg−1 at −60 °C and a long‐cycle life (over 200 days) at −30 °C. This study provides a new path to develop low‐concentration antifreezing electrolytes for aqueous electrochemical energy storage devices.

Measurements of the branching fractions B(B¯0→D*+π−) and B(B¯0→D*+K−) and tests of QCD factorization

Using (771.6±10.6)×106 BB¯ meson pairs recorded by the Belle experiment at the KEKB e+e− collider, we report the branching fractions B(B¯0→D*+π−)=(2.62±0.02±0.09)×10−3 and B(B¯0→D*+K−)=(2.22±0.06±0.08)×10−4; the quoted uncertainties are statistical and systematic, respectively. A measurement of the ratio of these branching fractions is also presented, RK/π=B(B¯→D*+K−)/B(B¯→D*+π−)=(8.41±0.24±0.13)×10−2, where systematic uncertainties due to the D*+ meson reconstruction cancel out. Furthermore, we report a new QCD factorization test based on the measured ratios for B¯→D*+h− and B¯→D*+ℓ−ν decays at squared momentum transfer values equivalent to the mass of the h=π or K hadron. The parameters |a1(h)| are measured to be |a1(π)|=0.884±0.004±0.003±0.016 and |a1(K)|=0.913±0.019±0.008±0.013, where the last uncertainties account for all external inputs. These values are approximately 15% lower than those expected from theoretical predictions. Subsequently, flavor SU(3) symmetry is tested by measuring the ratios for pions and kaons, |a1(K)|2/|a1(π)|2=1.066±0.042±0.018±0.023, as well as for different particle species. The ratio is consistent with unity and therefore no evidence for SU(3) symmetry breaking effects is found at the 5% precision level.Received 3 July 2022Accepted 10 October 2022DOI:https://doi.org/10.1103/PhysRevD.107.012003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasBranching fractionPhysical SystemsBottom mesonsParticles & Fields

Numerical analysis of coupled heat and mass transfer processes in packaged tomatoes throughout the cold chain

This study simulated the heat- and mass-transfer characteristics of fresh tomatoes by developing a computational fluid dynamics model. The root-mean-square error (RMSE) and mean absolute percentage error (MAPE) for the tomato temperature were 0.579 °C and 3.89%, respectively, and the RMSE and MAPE for the tomato mass loss were 0.737 g and 9.87%, respectively. Furthermore, the effect of different cold chain breaking (CCB) parameters on fluctuations in tomato temperature and mass loss were quantified by a sensitivity analysis. The results indicate that CCB increases the tomato temperature and moisture loss compared with an uninterrupted cold chain, especially for the tomato moisture loss during the second CCB because of the irreversibility and superposition of this negative effect. Furthermore, CCB would increase the inhomogeneity of the temperature distribution of packaged tomatoes but significantly reduce the inhomogeneity of tomato mass loss. Additionally, tomato temperature fluctuations are less sensitive to changes in relative humidity during the CCB process, and the sensitivity between them is almost two orders of magnitude less than the sensitivity of other CCB parameters. However, the loss of tomato mass proved to depend most strongly on variations in relative humidity and the least on variations in the CCB temperature.

Bayesian estimation of the low-energy constants up to fourth order in the nucleon-nucleon sector of chiral effective field theory

We use Bayesian methods and Hamiltonian Monte Carlo (HMC) sampling to infer the posterior probability density function (PDF) for the low-energy constants (LECs) up to next-to-next-to-next-to-leading order (N3LO) in a chiral effective field theory ($\ensuremath{\chi}\mathrm{EFT}$) description of the nucleon-nucleon interaction. In a first step, we condition the inference on neutron-proton and proton-proton scattering data and account for uncorrelated $\ensuremath{\chi}\mathrm{EFT}$ truncation errors. We demonstrate how to successfully sample the 31-dimensional space of LECs at N3LO using a revised HMC inference protocol. In a second step we extend the analysis by means of importance sampling and an empirical determination of the neutron-neutron scattering length to infer the posterior PDF for the leading charge-dependent contact LEC in the $^{1}S_{0}$ neutron-neutron interaction channel. While doing so we account for the $\ensuremath{\chi}\mathrm{EFT}$ truncation error via a conjugate prior. We use the resulting posterior PDF to sample the posterior predictive distributions for the effective range parameters in the $^{1}S_{0}$ wave as well as the strengths of charge-symmetry breaking and charge-independence breaking. We conclude that empirical point-estimate results of isospin breaking in the $^{1}S_{0}$ channel are consistent with the PDFs obtained in our Bayesian analysis and that, when accounting for $\ensuremath{\chi}\mathrm{EFT}$ truncation errors, one must go to next-to-next-to-leading order to confidently detect isospin breaking effects.

Predictive Control Method of Reaming up in the Raise Boring Process Using Kernel Based Extreme Learning Machine

Raise boring is an important method to construct the underground shafts of mines and other underground infrastructures, by drilling down the pilot hole and then reaming up to the desired diameter. Seriously different from the drilling operations of the mechanical parts in mechanized mass production, it is very difficult to obtain a good consistency in the construction environments of each raise or shaft, to be more exact, every construction process is highly customized. The underground bottom-up reaming process is impossible to be observed directly, and the rock breaking effect is very difficult to be measured in real-time, due to the rock debris freely falling under the excavated shaft. The optimal configurations of the operational parameters in the drilling and working pressures, torque, rotation speed and penetration speed, mainly depend on the accumulation of construction experience or empirical models. To this end, we presented a machine learning method, based on the extreme learning machine, to determine in real-time, the relationships between the working performance and the operational parameters, and the physical-mechanical properties of excavated geologic zones, aiming at a higher production or excavation rate, safer operation and minimum ground disturbance. This research brings out new possibilities to revolutionize the process planning paradigm of the raise boring method that traditionally depends on experience or subject matter expertise.

The translational μ-τ reflection symmetry of Majorana neutrinos

The present neutrino oscillation data allow [Formula: see text] (or [Formula: see text]) for the neutrino mass spectrum and support [Formula: see text] and [Formula: see text] as two good approximations for the PMNS lepton flavor mixing matrix [Formula: see text]. We show that these intriguing possibilities can be a very natural consequence of the translational[Formula: see text]-[Formula: see text] reflection symmetry — the effective Majorana neutrino mass term keeps invariant under the transformations [Formula: see text], [Formula: see text] and [Formula: see text] (for [Formula: see text] or 3), where [Formula: see text] is the charge conjugation of a constant spinor field [Formula: see text]. By extending such a working flavor symmetry to the canonical seesaw mechanism at a superhigh-energy scale, we calculate its soft breaking effects at the electroweak scale by using the one-loop renormalization-group equations.

Disintegration of beauty: a precision study

We update the Standard Model (SM) predictions for B-meson lifetimes within the heavy quark expansion (HQE). Including for the first time the contribution of the Darwin operator, SU(3)F breaking corrections to the matrix element of dimension-six four-quark operators and the so-called eye-contractions, we obtain for the total widths Gamma left({B}^{+}right)=left({0.58}_{-0.07}^{+0.11}right){textrm{ps}}^{-1},Gamma left({B}_dright)=left({0.63}_{-0.07}^{+0.11}right){textrm{ps}}^{-1},Gamma left({B}_sright)=left({0.63}_{-0.07}^{+0.11}right){textrm{ps}}^{-1} , and for the lifetime ratios τ(B+)/τ(Bd) = 1.086 ± 0.022, τ(Bs)/τ(Bd) = 1.003 ± 0.006 (1.028 ± 0.011). The two values for the last observable arise from using two different sets of input for the non-perturbative parameters {mu}_{pi}^2left({B}_dright),{mu}_G^2left({B}_dright) , and {rho}_D^3left({B}_dright) as well as from different estimates of the SU(3)F breaking in these parameters. Our results are overall in very good agreement with the corresponding experimental data, however, there seems to emerge a tension in τ(Bs)/τ(Bd) when considering the second set of input parameters. Specifically, this observable is extremely sensitive to the size of the parameter {rho}_D^3left({B}_dright) and of the SU(3)F breaking effects in {mu}_{pi}^2,{mu}_G^2 and {rho}_D^3 ; hence, it is of utmost importance to be able to better constrain all these parameters. In this respect, an extraction of {mu}_{pi}^2left({B}_sright),{mu}_G^2left({B}_sright),{rho}_D^3left({B}_sright) from future experimental data on inclusive semileptonic Bs-meson decays or from direct non-perturbative calculations, as well as more insights about the value of {rho}_D^3(B) extracted from fits to inclusive semileptonic B-decays, would be very helpful in reducing the corresponding theory uncertainties.

Control and symmetry breaking aspects of a geomagnetic field inversion model.

In this work, we consider the geomagnetic field inversion model proposed by Gissinger et al. [Europhys. Lett. 90(4), 49001 (2010)], where a quadratic term is added for symmetry control purposes. The resulting system is explored in both symmetric and asymmetric modes of operation. In the symmetric case, we report a bursting phenomenon and heterogeneous multistability of six and four different attractors. We show that the model owns an offset adjustment feature. In the asymmetric case, the model develops different phenomena, such as the coexistence of (four and three) asymmetric attractors, asymmetric (periodic and chaotic) bursting oscillation, and transient asymmetric bursting phenomenon. The effect of symmetry breaking is also manifested in the bubbles of bifurcation. It is shown that this system can leave from the multistable state to a monostable state by adjusting the coupling parameter of a linear controller. Moreover, microcontroller-based implementation of the system is considered to check the correctness of the numerical results.

Leading hadronic contribution to the muon g − 2 from lattice QCD

We compute the leading order hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon. The calculations are performed using four flavors of stout smeared staggered quarks, with quark masses at their physical values. The continuum limit is taken using six different lattice spacings ranging from 0.132 fm down to 0.064 fm. All strong isospin breaking and electromagnetic effects are accounted for to leading order. A controlled infinite volume limit is taken thanks to dedicated simulations performed in box sizes up to 11 fm. Putting all these ingredients together, we find [(gµ − 2)/2]LO−HVP = 707.5[5.5] 10−10, which has a total uncertainty of 0.8%. Compared to determinations based on the e+e− → hadrons cross section, our result significantly reduces the tension between the standard model prediction for the muon g − 2 and its experimental value.

Nonlinear Hall effects in two-dimensional moiré superlattices

The Hall effect refers to the generation of a voltage in a direction perpendicular to the applied current. Since its discovery in 1879, the Hall effect family has become a huge group, and its in-depth study is an important topic in the field of condensed matter physics. The newly discovered nonlinear Hall effect is a new member of Hall effects. Unlike most of previous Hall effects, the nonlinear Hall effect does not need to break the time-reversal symmetry of the system but requires the spatial inversion asymmetry. Since 2015, the nonlinear Hall effect has been predicted and observed in several kinds of materials with a nonuniform distribution of the Berry curvature of energy bands. Experimentally, when a longitudinal alternating current (AC) electric field is applied, a transverse Hall voltage will be generated, with its amplitude proportional to the square of the driving current. Such a nonlinear Hall signal contains two components: one is an AC transverse voltage oscillating at twice the frequency of the driving current, and the other is a direct current (DC) signal converted from the injected current. Although the history of the nonlinear Hall effect is only a few years, its broad application prospects in fields of wireless communication, energy harvesting, and infrared detectors have been widely recognized. The main reason is that the frequency doubling and rectification of electrical signals via some nonlinear Hall effects are achieved by an inherent quantum property of the material - the Berry curvature dipole moment, and therefore do not have the thermal voltage thresholds and/or the transition time characteristic of semiconductor junctions/diodes. Unfortunately, the existence of the Berry curvature dipole moment has more stringent requirements for the lattice symmetry breaking of the system apart from the spatial inversion breaking, and the materials available are largely limited. This greatly reduces the chance to optimize the signal of the nonlinear Hall effect and limits the application and development of the nonlinear Hall effect. The rapid development of van der Waals stacking technology in recent years provides a brand new way to design, tailor and control the symmetry of lattice, and to prepare artificial moiré crystals with certain physical properties. Recently, both theoretical results and experimental studies on graphene superlattices and transition metal dichalcogenide superlattices have shown that artificial moiré superlattice materials can have larger Berry curvature dipole moments than those in natural non-moiré crystals, which has obvious advantages in generating and manipulating the nonlinear Hall effect. On the other hand, abundant strong correlation effects have been observed in two-dimensional superlattices. The study of the nonlinear Hall effect in two-dimensional moiré superlattices can not only give people a new understanding of the momentum space distribution of Berry curvatures, contributing to the realization of more stable topological transport, correlation insulating states and superfluidity states, but also expand the functional space of moiré superlattice materials which are promising for the design of new electronic and optoelectronic devices. This review paper firstly introduces the birth and development of the nonlinear Hall effect and discusses two mechanisms of the nonlinear Hall effect: the Berry curvature dipole moment and the disorder. Subsequently, this paper summaries some properties of two-dimensional moiré superlattices which are essential in realizing the nonlinear Hall effect: considerable Berry curvatures, symmetry breaking effects, strong correlation effects and tunable band structures. Next, this paper reviews theoretical and experimental progress of nonlinear Hall effects in graphene and transition metal dichalcogenides superlattices. Finally, the future research directions and potential applications of the nonlinear Hall effect based on moiré superlattice materials are prospected.

Sedentary Behaviour-A Target for the Prevention and Management of Cardiovascular Disease.

Cardiovascular disease (CVD) is highly prevalent and can lead to disability and premature mortality. Sedentary behaviour, defined as a low energy expenditure while sitting or lying down, has been identified as an independent risk factor for CVD. This article discusses (1) the association of total sedentary time and patterns of accumulating sedentary time with CVD risk markers, CVD incidence and mortality; (2) acute experimental evidence regarding the acute effects of reducing and breaking up sedentary time on CVD risk markers; and (3) the effectiveness of longer-term sedentary behaviour interventions on CVD risk. Findings suggest that under rigorously controlled laboratory and free-living conditions, breaking up sedentary time improves cardiovascular risk markers in individuals who are healthy, overweight or obese, or have impaired cardiovascular health. Breaking up sedentary time with walking may have the most widespread benefits, whereas standing breaks may be less effective, especially in healthy individuals. There is also growing evidence that sedentary behaviour interventions may benefit cardiovascular risk in the longer term (i.e., weeks to months). Reducing and breaking up sedentary time may, therefore, be considered a target for preventing and managing CVD. Further research is needed to determine the effectiveness of sedentary behaviour interventions over the long-term to appropriately inform guidelines for the management of CVD.

Nigel Oscar Weiss. 16 December 1936—24 June 2020

Nigel Weiss was an astrophysicist and applied mathematician, born in South Africa but based in Cambridge for most of his career. He made a number of important contributions to the study of sunspots, where he produced a detailed model of their complex structure. He also made important contributions to theory of the solar 22-year magnetic cycle, using pioneering numerical modelling and drawing attention to the dynamical effects of symmetry breaking and of historic proxy data through observations of radioactive isotopes in tree rings and ice cores. A major part of his work was the numerical and theoretical investigation of many aspects of the interaction of magnetic fields with thermal convection in the Sun and stars. The numerical studies in particular were pioneering in the context of computer resources at that time. He led a talented group of students and postdocs, many of whom have held senior positions in UK and US universities. He combined great physical insight with expertise in numerical computation, nonlinear dynamics and bifurcation theory, and was an inspirational supervisor and mentor, combining high academic standards with an open generous nature. Apart from his work he had a strong interest in twentieth-century art and served on the National Gallery Consultative Group for many years.

Isospin symmetry breaking in the charge radius difference of mirror nuclei

Isospin symmetry breaking (ISB) effects in the charge radius difference $\mathrm{\ensuremath{\Delta}}{R}_{\mathrm{ch}}$ of mirror nuclei are studied using the test example of $^{48}\mathrm{Ca}$ and $^{48}\mathrm{Ni}$. This choice allows for a transparent study of ISB contributions since pairing and deformation effects, commonly required for the study of mirror nuclei, can be neglected in this specific pair. The connection of $\mathrm{\ensuremath{\Delta}}{R}_{\mathrm{ch}}$ with the nuclear equation of state and the effect of ISB on such a relation are discussed according to an energy density functional approach. We find that nuclear ISB effects may shift the estimated value for the symmetry energy slope parameter $L$ by about 6 to 14 MeV while Coulomb corrections can be neglected. ISB effects on the ground-state energy and charge radii in mirror nuclei have been recently predicted by ab initio calculations to be relatively small, pointing to a negligible effect for the extraction of information on the nuclear EoS. These contrasting results call for a dedicated theoretical effort to solve this overarching problem that impacts not only the neutron-skin thickness or the difference in mass and charge radii of mirror nuclei but also other observables such as the isobaric analog state energy.

Electronic properties of -Mn-type non-centrosymmetric superconductor Re5.5Ta under hydrostatic pressure

We have studied the effect of hydrostatic pressure on the superconducting and normal state properties of the non-centrosymmetric superconductor Re5.5Ta using magnetotransport, magnetization, and band structure studies. The superconducting transition temperature () reveals a modest decrease of ∼0.52 K as the external pressure is raised to 8 GPa. We found the Maki parameter, both at ambient and high pressures, suggesting the significant role of the Pauli pair breaking effect. Furthermore, the lower critical field was found to decrease with a rate of −1.74 mT GPa−1 as pressure increases to 1.05 GPa. Analysis of the thermally activated flux flow region of using the Arrhenius equation reveals the coexistence of single and collective vortex states. Further analysis of the critical current density indicates that the surface and volume pinning centers coexist and remain unaffected with varying pressure. Band structure calculations were performed using density functional theory and reveal a large bulk modulus, ∼ 289 GPa with ∼ 3.7, suggesting poor compressibility. In addition, we found that the density of states at the Fermi level barely reduces, even at pressures of up to 20 GPa. This is consistent with the experimental observation of robust superconductivity under compression.

Effects of Lorentz symmetry breaking environment on generalized relativistic quantum oscillator field

In this paper, we study the generalized Klein–Gordon oscillator under the effects of the violation of Lorentz symmetry defined by a tensor field ( KF) μναβ out of the standard model extension. We consider a possible scenario of Lorentz-violating with a Cornell-type potential form electric field and a linear magnetic field that contributes a harmonic-type central potential effects in the quantum motions of oscillator fields. The bound-state solutions of the wave equation using the parametric Nikiforov–Uvarov method by considering Coulomb- and Cornell-type potential form functions are obtained. We see that the eigenvalue solutions get modified by the Lorentz symmetry breaking effects in comparison to the Landau levels (without Lorentz-violation effects in flat space).

Charge-symmetry-breaking effects on neutron β decay in nonrelativistic quark models

A formalism for the study of charge-symmetry-breaking (CSB) effects is discussed and used to analyze the effects of charge-symmetry breaking on neutron $\ensuremath{\beta}$ decay. The effect of including CSB reduces the $\ensuremath{\beta}$-decay matrix element by an amount on the order of ${10}^{\ensuremath{-}4}$, a value much larger than the previous estimate. The earlier calculation used the neutron-proton mass difference as the CSB operator instead of the matrix element of the sum of the individual terms between the ground and excited states. The electromagnetic and dynamic effects of the up-down quark mass difference oppose the up-down quark mass difference leading to a small $n\ensuremath{-}p$ mass difference, but add coherently in computing the excitation matrix elements causing large enhancements. The current uncertainty in the value of ${V}_{ud}$ is also on the order of ${10}^{\ensuremath{-}4}$. An improvement of that uncertainty by an order of magnitude would require that charge-symmetry-breaking effects should be included in future analyses.