Abstract
We compute the Landau gauge quark propagator from lattice QCD with two flavors of dynamical O(a)-improved Wilson fermions. The calculation is carried out with lattice spacings ranging from 0.06 fm to 0.08 fm, with quark masses corresponding to pion masses of 420, 290 and 150 MeV, and for volumes of up to (4.5fm)^4. Our ensembles allow us to evaluate lattice spacing, volume and quark mass effects. We find that the quark wave function which is suppressed in the infrared, is further suppressed as the quark mass is reduced, but the suppression is weakened as the volume is increased. The quark mass function M(p^2) shows only a weak volume dependence. Hypercubic artefacts beyond O(a) are reduced by applying both cylinder cuts and H4 extrapolations. The H4 extrapolation shifts the quark wave function systematically upwards but does not perform well for the mass function.
Highlights
The quark propagator is one of the fundamental objects of QCD, and contains information regarding several of the core nonperturbative features of the theory, namely dynamical chiral symmetry breaking and the absence of quarks from the physical spectrum
A nonvanishing mass function even in the limit of vanishing bare quark mass is a direct sign of dynamical chiral symmetry breaking, while the absence of asymptotic quark states can be translated to an absence of real poles in the propagator, or equivalently, the lack of a positive spectral representation
We present a calculation of the quark propagator using gauge configurations with Nf 1⁄4 2 flavors of OðaÞ-improved Wilson fermion for nearly physical quark masses
Summary
The quark propagator is one of the fundamental objects of QCD, and contains information regarding several of the core nonperturbative features of the theory, namely dynamical chiral symmetry breaking and the absence of quarks from the physical spectrum (confinement). Lattice calculations provide us with an opportunity to study these essentially nonperturbative aspects of the quark propagator. After some early studies using Wilson fermions [9,10,11,12,13], most studies of the lattice Landau gauge quark propagator have used staggered [14,15,16,17] or overlap [18,19,20,21,22] fermions. We present a calculation of the quark propagator using gauge configurations with Nf 1⁄4 2 flavors of OðaÞ-improved Wilson fermion for nearly physical quark masses.
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