Related papers: B_K from improved staggered quarks
Improved staggered quark actions are designed to suppress flavour changing strong interactions. We discuss the perturbation theory for this type of actions and show the improvements to reduce the quark mass renormalisation compared to naive…
We present a preliminary calculation of B_K using domain-wall valence quarks and 2+1 flavors of improved staggered sea quarks. Both the size of the residual quark mass, which measures the amount of chiral symmetry breaking, and of the mixed…
We give an update on simulation results for the decay constants f_B, f_{B_s}, f_D and f_{D_s}. These decay constants are important for precision tests of the standard model, in particular entering as inputs to the global CKM unitarity…
We calculate the kaon B-parameter, B_K, in chiral perturbation theory for a partially quenched, mixed action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We find that the resulting expression is similar to that in…
We report on recent progress in the calculation of $B_K$ using HYP-smeared staggered fermions on the MILC asqtad lattices. Our main focus is on the continuum extrapolation, which is done using (up to) four different lattice…
Based on ongoing simulations, we update our results for low energy constants, decay constants, and light quark masses. The simulations employ three dynamical flavors of improved staggered quarks.
We present results for matching factors for staggered four-fermion operators constructed using HYP-smeared fat links both in the action and the operators. We use perturbation theory to calculate the matching factors and work to one-loop…
We present matching factors for $Z_q$ calculated perturbatively at the one-loop level with improved staggered quarks. We calculate $Z_q$ with HYP-smeared staggered quarks and Symanzik-improved gluons using both RI-MOM and RI$'$-MOM schemes.…
We compare several improved actions for staggered quarks. We study the effect of improvement on the taste changing interactions by calculating the splitting in the pion spectrum. We investigate the effect of the improvement on some…
We present an update on the analysis of semileptonic $B\rightarrow D^{(*)}$ decays at non-zero recoil. Our computation employs $2 + 1 + 1$ FNAL-MILC ensembles with highly improved staggered quark (HISQ) action for sea and light valence…
We study the pion spectrum (and in particular taste-symmetry breaking within it) using HYP-smeared valence staggered fermions on the coarse and fine MILC lattices (which have asqtad staggered sea quarks). We focus on the dependence on…
We present a new action for highly improved staggered fermions. We show that perturbative calculations for the new action are well-behaved where those of the conventional staggered action are badly behaved. We discuss the effects of the new…
We give a progress report on studies of B_s and B_d mixing with valence NRQCD b quarks and asqtad light quarks on the MILC configurations including the effect of 2+1 flavours of sea quarks. We explore methods for reducing statistical and…
We demonstrate the viability of improved staggered light quarks in studies of heavy-light systems. Our method for constructing heavy-light operators exploits the close relation between naive and staggered fermions. The new approach is…
The most recent calculations of pi+ pi+ and K+ K+ scattering by the NPLQCD collaboration using domain-wall valence quarks on staggered MILC configurations are presented. In addition, a quenched calculation of the potentials between two…
We give a progress report on the calculation of B meson mixing matrix elements, focusing on contributions that could arise beyond the Standard Model. The calculation uses asqtad (light quark) and Fermilab (heavy quark) valence actions and…
We present an update of the Fermilab Lattice and MILC Collaborations project to compute the form factors for semileptonic $B_{(s)}$-meson decays. Our calculation uses the highly improved staggered quark (HISQ) action for sea and valence…
We present an update of our study of high temperature QCD with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad staggered quark action. Simulations are being carried out on lattices with Nt=4, 6 and 8 for the…
Dramatic progress has been made over the last decade in the numerical study of quantum chromodynamics (QCD) through the use of improved formulations of QCD on the lattice (improved actions), the development of new algorithms and the rapid…
We are studying the effects of light dynamical quarks on the excitation energies of a flux tube between a static quark and antiquark. We report preliminary results of an analysis of the ground state potential and the $\Sigma^{\prime+}_g$…