查看更多>>摘要：The effect of finite coupling corrections to the Langevin diffusion coefficients on a moving heavy quark in the Super Yang-Mills plasma was investigated.These corrections are related to curvature squared corrections in the corresponding gravity sector.We compared the results of both longitudinal and perpendicular Langevin diffu-sion coefficients with those for N=4 Super Yang-Mills plasma.It was observed that the curvature-squared correc-tions influence the Langevin diffusion coefficients,and the corrections for both Langevin diffusion coefficients demonstrate the dependence on the velocity of the moving heavy quark and the specifics of the higher derivative cor-rection.In addition,we conducted calculations for the Langevin diffusion coefficients of a moving heavy quark within the Gauss-Bonnet background.
查看更多>>摘要：The relativistic Hartree-Bogoliubov(RHB)theory is a powerful tool for describing exotic nuclei near drip lines.The key technique is to solve the RHB equation in the coordinate space to obtain the quasi-particle states.In this paper,we solve the RHB equation with the Woods-Saxon-type mean-field and Delta-type pairing-field poten-tials by using the finite-difference method(FDM).We inevitably obtain spurious states when using the common symmetric central difference formula(CDF)to construct the Hamiltonian matrix,which is similar to the problem resulting from solving the Dirac equation with the same method.This problem is solved by using the asymmetric difference formula(ADF).In addition,we show that a large enough box is necessary to describe the continuum quasi-particle states.The canonical states obtained by diagonalizing the density matrix constructed by the quasi-particle states are not particularly sensitive to the box size.Part of the asymptotic wave functions can be improved by applying the ADF in the FDM compared to the shooting method with the same box boundary condition.
查看更多>>摘要：The Cd puzzle implies that the phonon excitation of a spherical nucleus should be questioned and re-futed.To understand the newly and experimentally discovered spherical-like y-soft mode,the SU3-IBM was re-cently proposed.In this study,the evolutions of the normal states in 108-120Cd are investigated and compared with the experimental results.To better explain the nearly zero B(E2)values between the 02+and 2 1+states,SU(3)higher-order interactions except for the SU(3)second-order and third-order Casimir operators are also considered in detail.We find that the results of theoretical fitting and experimental data agree well with simple parameter selection,and the spherical-like spectra truly exist.The deficiency may arise from the lack of configuration mixing.The realistic spectra characteristics of the spherical-like spectra are found for 118,120 Cd,and the electric quadrupole moments of the 2 1+state are predicted.The Q2 1+anomaly in 108-116 Cd is also discussed.
查看更多>>摘要：The application scope of the analytic continuation in the coupling constant(ACCC)can be extended to the exchange parameters of the effective nucleon-nucleon interaction in the microscopic cluster model.Based on such an exchange parameter dependent ACCC(abbreviated as EPD-ACCC),we examine the Λ9Be system in the framework of the α+α+Λ microscopic cluster model.The particle emission from excited states of α+α+Λare in-vestigated,and the corresponding resonant energies are obtained via EPD-ACCC.Furthermore,the complex scaling method(CSM)is applied for comparison.A good agreement between these two theoretical approaches is obtained.This study demonstrates EPD-ACCC to be a reliable method for estimating multi-cluster resonances in light hyper-nuclei.
查看更多>>摘要：Analysis of Pb+Pb data for net-charge fluctuations at LHC energies using the HYDJET++model is presented.The strongly intensive quantities D and Σ were used to remove the effects related to system volume fluc-tuations.We employed two versions of HYDJET++for the analysis.The first one is the standard or default version,whereas the second one is a modification that takes into account explicit event-by-event conservation of the electric net-charge of produced particles.The inclusion of the canonical net-charge conservation in the model allows for bet-ter description of the experimental data obtained by the ALICE and CMS Collaborations.A comparison with calcu-lations from other models is also presented.
查看更多>>摘要：Dark energy is typically the principal component needed for the traversability of wormholes(WH),as it provides the negative gravity effect required to keep the throat open.However,can this be achieved without dark en-ergy?It turns out that if we couple the trace of energy-momentum with the standard Einstein-Hilbert Lagrangian and utilize a specific equation of state(EoS),dark energy may be obviated.The Casimir stress energy is known to result in the violation of the null energy condition(NEC)on the energy momentum tensor.This phenomenon makes such an EoS an ideal candidate for generating traversable WH geometries.The laboratory proven phenomenon provides a natural mechanism to sustain an open WH throat without relying on dark energy.Therefore,we generate two classes of WH solutions using this in energy-momentum trace-coupling gravity.For the specific choice of the Casimir EoS relating the energy-momentum tensor components[Kar and Sahdev:Phys.Rev.D 52,2030(1995)]and different choices of redshift functions,we determine the WH geometry completely.The obtained WH solutions violate the NECs,and all qualitative constraints demanded for physically realizable WHs are satisfied.This is demonstrated via graphical plots for a suitably chosen range of coupling parameter values.Furthermore,our study investigates the re-pulsive effect of gravity,revealing that its presence leads to a negative deflection angle for photons traveling along null geodesics.Notably,we observe a consistent pattern of negative values for the deflection angle across all values of r0 in the three scenarios considered,thus indicating the clear manifestation of the repulsive gravity effect.All of this is possible without invoking the existence of dark energy.
查看更多>>摘要：This study explores the f(R,T)gravity theory,which introduces a coupling between matter and curvature,through the simplest linear functional form f(R,T)=R+2βT.We derive the modified Einstein field equations and conservation equations for this theory and then apply this framework to study the structural properties of quark stars(QSs)composed of interacting quark matter,considering perturbative QCD corrections and color su-perconductivity.By solving the modified Tolman-Oppenheimer-Volkoff equations,we investigate the mass-radius relation,stability criteria,and energy conditions of QSs.Our results indicate that the f(R,T)gravity significantly in-fluences the properties of QSs,leading to deviations from General Relativity.The analysis is consistent with recent observational data,suggesting that the modified gravity framework could provide viable models for the study of compact stars.
查看更多>>摘要：Using a dynamical system method,we study a Friedmann-Robertson-Walker(FRW)cosmological mod-el within the context of f(Q,C)gravity,where Q is the non-metricity scalar and C represents the boundary term,considering both interacting and non-interacting models.A set of autonomous equations is derived,and solutions are calculated accordingly.We assess the critical points obtained from these equations,identify their characteristic val-ues,and explore the physical interpretation of the phase space for this system.Two types of f(Q,C)are assumed:(ⅰ)f(Q,C)=Q+αQ+βClogC and(ⅱ)f(Q,C)=Q+αQ+β/C,where α and 6 are the parameters.In Model I,we ob-tain two stable critical points,whereas in Model Ⅱ,we identify three stable critical points for both interacting and non-interacting models.We examine the behavior of phase space trajectories at every critical point.We calculate the values of the physical parameters for both systems at each critical point,indicating the accelerated expansion of the Universe.
查看更多>>摘要：The cosmic distance duality relation(DDR),which links the angular-diameter and luminosity distances,is a cornerstone in modern cosmology.Any deviation from DDR may indicate new physics beyond the standard cos-mological model.In this study,we used four high-precision time-delayed strong gravitational lensing(SGL)sys-tems provided by H0LiCOW to test the validity of DDR.To this end,we directly compared the angular-diameter distances from these SGL systems with the luminosity distances from the latest Pantheon+compilation of SNe Ia.To reduce the statistical errors arising from redshift matching,a Gaussian process method was applied to reconstruct the distance-redshift relation from the Pantheon+dataset.We parameterized the possible violation of DDR in three dif-ferent models.All results confirm the validity of DDR at lσ confidence level.Additionally,Monte Carlo simula-tions based on the future LSST survey indicated that the precision of DDR could reach the 10-2 level with 100 SGL systems.
查看更多>>摘要：We investigate mass ladder operators for the static BTZ-like black hole in Einstein-bumblebee gravity and probe the quasinormal frequencies of the mapped modes using mass ladder operators for a scalar perturbation under Dirichlet and Neumann boundary conditions.We find that the mass ladder operators depend on the Lorentz symmetry breaking parameter,and the imaginary parts of the frequencies shifted by the mass ladder operators in-crease with the increase in the Lorentz symmetry breaking parameter under the two boundary conditions.Note that,under the Neumann boundary condition,the mapped modes caused by the mass ladder operator D0,k+are unstable.Moreover,the mass ladder operators do not change the Breitenlohner-Freedman bound for the scalar modes,as in the case of the usual BTZ black hole.These results could aid us in further understanding the conformal symmetry and Lorentz symmetry breaking in Einstein-bumblebee gravity.
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