Proper time evolution of magnetic susceptibility in a magnetized quark-gluon plasma

In ultrarelativistic heavy-ion collisions, enormous magnetic fields are generated because of fast-moving charged particles. In the presence of these magnetic fields, the spin of particles is aligned either in the parallel or in the antiparallel direction with respect to the direction of the magnetic field. A finite magnetization is thus produced. It is known that a finite magnetic susceptibility, \(\chi_{m}\), changes the evolution of the energy density of the quark-gluon plasma (QGP), which is believed to be created in these collisions. Depending on whether the system under consideration is a paramagnetic (\(\chi_{m}>0\)) or diamagnetic (\(\chi_{m}