Lattice QCD with 8 Light Quark Flavors

TL;DR

This study investigates lattice QCD with eight light quark flavors across various lattice sizes, revealing a strong first-order transition at small sizes that becomes a zero-temperature transition at larger sizes, with implications for chiral symmetry.

Contribution

It provides the first detailed lattice study of eight-flavor QCD, analyzing the nature of phase transitions and chiral symmetry restoration at different lattice scales.

Findings

First-order transition observed at small lattice sizes.

Transition becomes zero-temperature and scale-changing at larger sizes.

Chiral symmetry is restored in the strong-coupling phase.

Abstract

QCD with eight flavors is studied on $16^3\times N_t$ lattices with $N_t=4$, 6, 8, 16 and 32, a dynamical quark mass $ma=0.015$ and lattice coupling $\beta=6/g^2$ between 4.5 and 5.0. For $N_t=16$ and 32, hadron masses and screening lengths are computed for a variety of valence quark masses. The previously observed, strong, first-order transition for $N_t=4$, 6 and 8 is seen, for $N_t=16$, to become a $\beta$-independent, zero-temperature transition characterized by a factor of $\approx 3$ change in lattice scale. This strong, first-order transition restores chiral symmetry, at least for $N_t=4$, 6 and 8, producing a chirally symmetric, weak-coupling phase. However, as $N_t$ increases to 16, the chiral symmetry properties of the weak-coupling side of the zero-temperature transition are unclear and offer a hint of a normal, finite-temperature, chiral symmetry breaking transition in the weak-coupling phase.