The Gross–Neveu model from string theory

We study an intersecting D-brane model which at low energies describes (1+1)(1+1)-dimensional chiral fermions localized at defects on a stack of NcNc D4-branes. Fermions at different defects interact via exchange of massless (4+1)(4+1)-dimensional fields. At weak coupling this interaction gives rise to the Gross–Neveu (GN) model and can be studied using field theoretic techniques. At strong coupling one can describe the system in terms of probe branes propagating in a curved background in string theory. The chiral symmetry is dynamically broken at zero temperature and is restored above a critical temperature TcTc which depends on the coupling. The phase transition at TcTc is first order at strong coupling and second order at weak coupling.