Chiral phase transition in soft-wall AdS=QCD with scalar-dilaton coupling

The chiral phase boundary of nuclear matter is expected to have a critical point where the rapid crossover of lattice methods at zero chemical potential becomes a first-order phase transition. Phenomenological models based on the AdS/CFT correspondence, known as AdS=QCD, have succeeded in capturing many features of nuclear matter, with recent progress in producing the expected critical point. We study a model that produces a critical point in the chiral phase diagram by introducing a coupling between the scalar chiral field and the dilaton. We examine the effect of the scalar-dilaton coupling on the critical point. We also study the zero-temperature chiral dynamics, which must allow for spontaneous chiral symmetry breaking in the limit of zero quark mass. We find that when the scalar-dilaton coupling is large enough to ensure correct zero-temperature chiral dynamics, a critical point is present only if the quark mass is greater than 12.8 MeV.