Tricritical scaling at the N_t=6 chiral phase transition for 2 flavour lattice QCD with staggered quarks
Abstract
We have simulated lattice QCD directly in the chiral limit of zero quark mass by adding an additional, irrelevant 4-fermion interaction to the standard action. Using lattices having temporal extent of six and spatial extents of twelve and eighteen, we find that the theory with 2 massless staggered quark flavors has a second order finite temperature phase transition. The critical exponents
β
mag
,
δ
and
ν
are measured and favour tricritical behaviour over that expected by universality arguments. The pion screening mass is consistent with zero below the transition, but is degenerate with the nonzero
σ(
f
0
)
mass above the transition, indicating the restoration of chiral symmetry.