Probing surface vibration of spherical nuclei in relativistic heavy-ion collisions

There has been increasing interest in recent years in using relativistic heavy-ion collisions to probe nuclear structure, such as static nuclear deformation. Here we discuss the role of quantum zero-point fluctuations of the surface vibration of spherical nuclei in relativistic heavy-ion collisions. To this end, we employ an approach to describe the vibration in the space-fixed frame, which has been well established in the field of low-energy heavy-ion fusion reactions. We particularly consider the quadrupole vibration of $^{58}$Ni in $^{58}$Ni+$^{58}$Ni reaction and the octupole vibration of $^{208}$Pb in $^{208}$Pb+$^{208}$Pb reaction. We show that the surface vibration leads to comparable eccentricity parameters to those for static deformation, while they give significantly different distributions of the initial states, suggesting the importance of the proper treatment of the surface vibration in heavy-ion collisions. We perform similar analysis also for triaxial deformation and gamma-soft vibration.