Thursday, December 20, 2012

1212.4624 (Daniel D. Scherer et al.)

Many-flavor Phase Diagram of the (2+1)d Gross-Neveu Model at Finite
Temperature
   [PDF]

Daniel D. Scherer, Jens Braun, Holger Gies
We study the phase diagram of the Gross-Neveu model in d=2+1 space-time dimensions in the plane spanned by temperature and the number of massless fermion flavors. We use a functional renormalization group approach based on a nonperturbative derivative expansion that accounts for fermionic as well as composite bosonic fluctuations. We map out the phase boundary separating the ordered massive low-temperature phase from the disordered high-temperature phase. The phases are separated by a second-order phase transition in the 2d Ising universality class. We determine the size of the Ginzburg region and show that it scales to zero for large $\Nf$ following a powerlaw, in agreement with large-$\Nf$ and lattice studies. We also study the regimes of local order above as well as the classical regime below the critical temperature.
View original: http://arxiv.org/abs/1212.4624

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