Sourav ChaudharyJitendra KumarS K MauryaSweeti Kiroriwal...
114-127页
查看更多>>摘要：In this work,we have explored wormhole(WH)solutions in F(R,(£)m)gravity by assuming the Morris-Thome WH metric and F(R,(£)m)=R/2+(1+γR)(£)m,where γ is the free model parameter.We determined the WH solutions by utilizing two newly developed shape functions(SF)that satisfy all basic conditions for a WH's physical validity.We also observe that the null energy condition(NEC)behaves negatively.Finally,for both models,we use the volume integral quantifier(VIQ)and Tolman-Oppenheimer-Volkoff(TOV)equation to determine how much exotic matter is needed near the WH throat and the stability of the WH.The extensive detailed discussions of the matter components have been done via graphical analysis.The obtained WH geometries meet the physically acceptable conditions for a stable wormhole.
查看更多>>摘要：The paper investigates the escape probability for isotropic emitters near a Kerr black hole.We propose a new approach to obtain the escape probability in a general manner,going beyond previous case-by-case studies.This approach is based on studies of the black hole shadow with astrometric observable and can be applied to emitters with an arbitrary 4-velocities and locations,even to the emitters outside of the equatorial plane.We also consider representative examples illustrating how escape probabilities vary with distance,velocity,and inclination angle.Overall,this new approach provides an effective method for studying escape probabilities near Kerr black holes.
查看更多>>摘要：Supermassive black holes(SMBHs)are ubiquitous in the center of galaxies,although the origin of their massive seeds is still unknown.In this paper,we investigate the formation of SMBHs from the quantum chromodynamics(QCD)axion bubbles.In this case,primordial black holes(PBHs)are considered as the seeds of SMBHs,which are generated from the QCD axion bubbles due to an explicit Peccei-Quinn(PQ)symmetry breaking after inflation.The QCD axion bubbles are formed when the QCD axion starts to oscillate during the QCD phase transition.We consider a general case in which the axion bubbles are formed with the bubble effective angle θeff ∈(0,π],leading to the minimum PBH mass～O(104-107)M☉ for the axion decay constant fa～O(1016)GeV.The PBHs at this mass region may account for the seeds of SMBHs.
查看更多>>摘要：Motivated by experiments with interacting quantum gases across high partial wave resonance,we investigate the thermodynamic properties and single-particle spectra of Bose gases in normal phase for different interaction strengths for both p-and d-wave interactions.The equation of state,contact density,momentum distributions and self-energies of single-particle Green's functions are obtained in the spirit of ladder diagram approximations.The radio-frequency(RF)spectrum,as an important experimental approach for detecting Feshbach molecules or the interaction effect,is calculated at different temperatures.A reversed temperature dependence on the Bose-Einstein condensation side and Bardeen-Cooper-Schrieffer side is identified for both p-and d-wave interactions.An estimate for the signal of RF spectra under typical experimental conditions is also provided.
查看更多>>摘要：The Stokes-Einstein-Debye(SED)relation is proposed to be broken down in supercooled liquids by many studies.However,conclusions are usually drawn by testing some variants of the SED relation rather than its original formula.In this work,the rationality of the SED relation and its variants is examined by performing molecular dynamics simulations with the Lewis-Wahnstrom model of ortho-terphenyl(OTP).The results indicate the original SED relation is valid for OTP but the three variants are all broken down.The inconsistency between the SED relation and its variants is analyzed from the heterogeneous dynamics,the adopted assumptions and approximations as well as the interactions among molecules.Therefore,care should be taken when employing the variants to judge the validity of the SED relation in supercooled liquids.
查看更多>>摘要：Flocking and vortical are two typical motion modes in active matter.Although it is known that the two modes can spontaneously switch between each other in a finite-size system,the switching dynamics remain elusive.In this work,by computer simulation of a two-dimensional Vicsek-like system with 1000 particles,we find from the perspective of the classical nucleation theory that the forward and backward switching dynamics are asymmetric:going from flocking to vortical is a one-step nucleation process,while the opposite is a two-step nucleation process,with the system staying in a metastable state before reaching the final flocking state.
查看更多>>摘要：The phase transition of water molecules in nanochannels under varying external electric fields is studied by molecular dynamics simulations.It is found that the phase transition of water molecules in nanochannels occurs by changing the frequency of the varying electric field.Water molecules maintain the ice phase when the frequency of the varying electric field is less than 16 THz or greater than 30 THz,and they completely melt when the frequency of the varying electric field is 24 THz.This phenomenon is attributed to the breaking of hydrogen bonds when the frequency of the varying electric field is close to their inherent resonant frequency.Moreover,the study demonstrates that the critical frequency varies with the confinement situation.The new mechanism of regulating the phase transition of water molecules in nanochannels revealed in this study provides a perspective for further understanding of the phase transition of water molecules in nanochannels,and has great application potential in preventing icing and deicing.
查看更多>>摘要：This work focuses on the ground-state phase diagram,the compensation temperatures and the critical behaviors of a ferrimagnetic graphene-like trilayer induced by crystal fields and exchange couplings.The simulation results show that a negative decrease in crystal field or an increase in exchange coupling can increase the critical temperature.More importantly,an M curve with double compensation temperatures can be observed,which is not predicted by the Néel theory.This remarkable compensation phenomenon has potential application value in the field of magnetic recording.
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