Neutral pion masses within a hot and magnetized medium in a lattice-improved soft-wall AdS / QCD model

We investigate chiral phase transitions and the screening masses, pole masses, and thermal widths of neutral pion mesons with finite temperature T and magnetic field B in a lattice-improved AdS / QCD model, which is constructed by fitting the lattice results of the pseudocritical temperatures T pc ( B ) . Specifically, we find that the chiral condensate σ undergoes a crossover phase transition demonstrating distinct magnetic catalysis and inverse magnetic catalysis effects in very low- and high-temperature regions with fixed finite B , respectively. For the screening masses, we find that the longitudinal component decreases with B at very low and high temperatures and increases with B near T pc . The transverse component always increases with B at fixed T . However, both the longitudinal and transverse screening masses increase with T at fixed B . Furthermore, we find that the pole mass decreases with the increase of B or T . It is interesting to note that the thermal width shows similar behavior to the longitudinal screening masses in the very-high-temperature region.