相关论文: Sea Quark Effects on the Strong Coupling Constant

We compute the matching relation for the strong coupling constant within the framework of QCD up to four-loop order. This allows a consistent five-loop running (once the $\beta$ function is available to this order) taking into account…

We present the results of a partially quenched lattice QCD calculation of light quark masses with $N_f=2$ degenerate dynamical flavors. Numerical simulations are carried out using the plaquette gauge action and the Wilson quark action at…

A robust thermodynamic argument shows that a small reduction of the effective coupling constant $\alpha$ of QED greatly enhances the Compton scattering cross section and that the Thomson scattering length is connected to a fundamental scale…

We study the strong interactions among the heavy bottom spin--1/2 $\Sigma_b$ baryon, nucleon and $B$ meson as well as the heavy charmed spin--1/2 $\Sigma_c$ baryon, nucleon and $D$ meson in the context of QCD sum rules. We calculate the…

We estimate the effects on the decay constants of charmonium and on heavy meson masses due to the charm quark in the sea. Our goal is to understand whether for these quantities $N_f=2+1$ lattice QCD simulations provide results that can be…

We study the effects of dynamical quarks on the static quark potential at distances shorter than those where string breaking is expected. Quenched calculations and calculations with three flavors of dynamical quarks are done on sets of…

The coupling constant of the meson vertex $J/\psi D_s D_s$ is calculated using the three point correlation function within the QCD Sum Rule formalism. We have considered alternately mesons $J/\psi$ and $D_s$ off-shell together with…

We consider the effect of a six-fermion interaction of the {'}t Hooft form in the quark-quark channel on the ground state of matter at finite density. The coupling constant for this new term is varied within the limits suggested by…

We present a status report of our ongoing effort toward a precision determination of the kaon $B$ parameter with the Kogut-Susskind quark action in quenched QCD. Results for $B_K$ so far accumulated at $\beta =5.85$, 5.93, 6.0 and 6.2…

The strong coupling constants of hadronic multiplets are fundamental parameters which carry information of the strong interactions among participating particles. These parameters can help us construct the hadron-hadron strong potential and…

Results of a systematic lattice QCD simulation with two degenerate flavors of sea quarks, identified as dynamical u and d quarks, are presented. The simulation was performed on a dedicated parallel computer, called CP-PACS, developed at the…

We present a determination of the strong coupling constant $\alpha_s(m_Z)$ using inclusive top-quark pair production cross section measurements performed at the LHC and at the Tevatron. Following a procedure first applied by the CMS…

We study the change in free and internal energy due to the presence of a heavy quark anti-quark pair in a thermal heat bath in QCD with 2-flavors of staggered quarks at finite temperature. We discuss string breaking below as well as…

We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge…

We study the static potential using gauge configurations that include the effects of two flavors of dynamical Kogut-Susskind quarks. The configurations, generated by the MILC collaboration, and used to study the spectrum and heavy-light…

A brief overview of the lattice technique of studying QCD is presented. Recent results from the UKQCD Collaboration's simulations with dynamical quarks are then presented. In this work, the calculations are all at a fixed lattice spacing…

We study the critical behavior of the chiral condensate near the QCD phase transition in the background of two fixed light dynamical (sea) quarks. We study the condensate for $5.245 \leq \beta \leq 5.3$ and $10^{-10} \leq m_{val} \leq 10$

We compute $\Lambda_{\bar{MS}}$ for two flavors of light dynamical quarks using non-perturbatively $O(a)$ improved Wilson fermions. We improve on a recent calculation by employing Pad\'e-improved two-loop and three-loop perturbation theory…

In this work we present lattice calculations of the masses of P-wave mesons using Monte Carlo simulations. Our valence fermions are defined by the Wilson action. Our gauge fields are generated with both dynamical staggered fermions at a…

Two twisted doublets, one containing the up and down quarks and the other containing the strange quark with an SU(2)-flavor partner, are used for studies in the meson sector. The relevant chiral perturbation theory is presented, and…