2+1 flavor QCD with the fixed point action in the $epsilon$-regime.pdf
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2+1 flavor QCD with the fixed point action in the
ε-regime
Peter Hasenfratz
a
, Dieter Hierl
?b
, Vidushi Maillart
a
, Ferenc Niedermayer
a
,
Andreas Sch?fer
b
, Christof Weiermann
a
, Manuel Weingart
a
BGR (Bern-Graz-Regensburg) Collaboration
a
Institute for Theoretical Physics, University of Bern, CH-3012 Bern, Switzerland
b
Institute for Theoretical Physics, University of Regensburg, D-93040 Regensburg, Germany
E-mail: dieter.hierl@physik.uni-regensburg.de
We generated configurations with the approximate fixed-point Dirac operator DFP on a 12
4
lattice
with a ≈ 0.13 fm where the scale was set by r0. The distributions of the low lying eigenvalues
in different topological sectors were compared with those of the Random Matrix Theory which
leads to a prediction of the chiral condensate.
The XXV International Symposium on Lattice Field Theory
July 30 - August 4 2007
Regensburg, Germany
?
Speaker.
c? Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. http://pos.sissa.it/
2+1 flavor QCD in the ε-regime Dieter Hierl
1. Introduction
The ε-expansion, where mπL? 1 and 4πF
2
L
2 ? 1, is determined by Goldstone boson physics.
For that reason it is an excellent tool to determine the low-energy constants of ChPT of QCD. In
order to reach this regime the simulation should be done with sufficiently small quark masses.
This requires a Dirac operator with good chiral behavior at the actual lattice spacing. This became
possible in full QCD only recently [1, 2, 3, 4].
We consider 2+1 light flavor QCD applying the parametrized fixed-point (FP) action [4]. The
exact FP action has nice features, most importantly, it has exact chiral symmetry. The parametrized
FP action is an approximation which gave very promising results in the quenched approximation,
in particular good scaling even at a = 0.15 fm and the spectrum of the FP Dirac operator was cl
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