Squeezed Back-to-back Correlation Of D~0(?)~0 In Relativistic Heavy-ion Collisions

The boson becoming into quasi-particle for the interaction with medium before its therm-mal freeze-out in high energy heavy ion collision,which will cause its mass modification and then result in a squeezed back-to-back correlation(BBC)of boson-antiboson pairs.This BBC connects with the bogoliubov transformation between the creation(annihilation)operator of free particle and quasi-particle.In addition,it is expected to be strong for the bosons with a lager mass under the same mass shift.In this paper,we investigate the BBC ofD~0(?)~0 for anisotropic gaussian and hydrodynamic expanding sources.Because the environment of hadronic emission source is baryon dilute and meson rich in ultra-relativistic heavy-ion collisions at RHIC or LHC energies,we adopt simply the D meson interact with pion meson in calculating its mass shift and width.The space density distribution and expanding velocity of particle emission source produced in relativistic heavy-ion collisions is anisotropic.When we study the BBC(21pp-(28))of D~0(?)~0 in the anisotropic gaussian expanding sources,we assume the particle meets its freeze-out suddenly and the freeze-out temperature is taken to be 150 Me V.The mass of quasi-particle of00D/D is chosen to be peak from its in-medium mass distribution.We calculate the BBC function of D~0(?)~0 using a Monte Carlo method and analyze how the D~0 meson momentum,source velocity and the angle between them affect the BBC.In the anisotropic gaussian expanding sources,the results manifest the BBC increases with the increasing D~0 meson momentum for a given source velocity,reaches maximum as the D~0 meson momentum in big area is perpendicular to source velocity and minimum as the D~0 meson momentum in big area parallel to source velocity for a fixed D~0 meson momentum value.Recently,relativistic hydrodynamics has become an efficient tool in describing the evolution of particle-emitting sources in high energy heavy-ion collision and widely used to study some observables such as the momentum spectra and anisotropic flows.Then,we continue the investigation of the BBC in this situation.We calculated the BBC C))(((35)f by the viscous hydrodynamic code VISH2+1 with the MC-Glb initial condition for Au+Au collision at esVG200NN(28)in centrality intervals 0%-80% and 40%-80%.The ratio of the shearviscosity to entropy density of the quark gluon plasma(QGP)and the freeze-out temperature are taken to be 0.08 and 150 Me V,respectively.The results display the BBC of D~0(?)~0 is evidently greater than 1 as the D~0 meson momentum is approximately perpendicular to the other,and decreases with increasing the D~0 meson momentum for a fixed angle between one D~0 meson momentum and anotherD~0 meson momentum in their pairs.This reach also reveals people can detect BBC using the D~0 mesons with masses smaller than the maximum observed in experiment.