Lattice QCD with eight Hght-quark flavors

QCD with eight flavors is studied on ${16}^{3}\ifmmode\times\else\texttimes\fi{}{N}_{t}$ lattices with ${N}_{t}=4,6, \mathrm{and} 8$, a dynamical quark mass $ma=0.015$, and lattice coupling $\ensuremath{\beta}=\frac{6}{{g}^{2}}$ between 4.5 and 5.0. For ${N}_{t}=16$, hadron masses and screening lengths are computed for a variety of valence quark masses. The previously observed, strong, first-order transition for ${N}_{t}=4,6, \mathrm{and} 8$ is seen, for ${N}_{t}=16$, to become a $\ensuremath{\beta}$-independent, zero-temperature transition characterized by a factor of \ensuremath{\cong} 3 change in lattice scale. This strong, first-order transition restores chiral symmetry, at least for ${N}_{t}=4,6, \mathrm{and} 8$, 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.