We present a lattice simulation study of large $N_c$ regularities of meson and baryon spectroscopy in $SU(N_c)$ gauge theory with two flavors of dynamical fundamental representation fermions. Systems investigated include $N_c=2$, 3, 4, and 5, over a range of fermion masses parametrized by a squared pseudoscalar to vector meson mass ratio between about 0.2 to 0.7. Good agreement with large $N_c$ scaling is observed in the static potential, in meson masses and decay constants, and in baryon spectroscopy. This is an update of the published version of the paper (Phys. Rev. D94 (2016) 034506).
We present a first look at the spectroscopy of SU(4) gauge theory coupled to two flavors of Dirac fermions in the two-index antisymmetric representation, which is a real representation. We compute meson and diquark masses, the pseudoscalar and vector meson decay constants, and the masses of six-quark baryons. We make comparisons with large-Nc expectations.
We present an analysis of the isospin-one V-A correlator based on our successful simultaneous description of the OPAL V and A non-strange tau spectral data. We discuss the values obtained for the Chiral Perturbation Theory low-energy constants L_10 and C_87 as well as the dimension-six and eight condensates and compare them with those in the literature.
We summarize our recent work on gauge theories with two flavors of fermions in the two-index symmetric representation: SU(2) gauge theory with adjoint fermions, SU(3) with sextets, and SU(4) with ten-dimensional-representation fermions. All three systems have beta functions smaller than their perturbative value, approaching a fixed point near the expected two-loop zero. In all cases the mass anomalous dimension is small, under 0.5.
We study the temperature dependence of bottomonium for temperatures in the range $0.4 T_c < T < 2.1 T_c$, using nonrelativistic dynamics for the bottom quark and full relativistic lattice QCD simulations for $N_f=2$ light flavors on a highly anisotropic lattice. We find that the $Υ$ is insensitive to the temperature in this range, while the $χ_b$ propagators show a crossover from the exponential decay characterizing the hadronic phase to a power-law behaviour consistent with nearly-free dynamics at $T \simeq 2 T_c$.
The critical temperature and the nature of the QCD finite temperature phase transition are determined for Nf=2 dynamical flavors of nonperturbatively improved Wilson fermions. The calculations are performed on large lattices with temporal extents Nt=12, 10 and 8, and lattice spacings down to a = 0.075 fm. We find the deconfinement and chiral phasetransitions to take place at the same temperature. Our results are in broad agreement with a second order phase transition in the chiral limit. The critical temperature at the physical quark mass is found to be Tc = 174(3)(6) MeV.