Article

# Scaling behavior and sea quark dependence of pion spectrum with HYP-smeared staggered fermions

[more]
09/2008;
Source: arXiv

ABSTRACT

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 lattice spacing and sea-quark mass. We also update our results on source dependence. Our main conclusion is that on the MILC fine lattices the appropriate power-counting for SU(3) staggered chiral perturbation theory may have discretization errors entering at next-to-leading order rather than at leading-order. Comment: 7 pages, 8 figures, Lattice 2008 proceeding

### Full-text

Available from: Stephen R. Sharpe, Dec 17, 2014
• Source
##### Article: Calculating $B_K$ using HYP staggered fermions
[Hide abstract]
ABSTRACT: We give an update on our calculation of $B_K$ using HYP-smeared valence staggered quarks. We have results for $B_K$ at tree-level on several coarse MILC lattices ($a\approx 0.12$fm) and one of the fine lattices ($a\approx 0.09$fm), using 10 light valence quarks ranging down to $m_s^{\rm phys}/10$. We have generalized staggered chiral perturbation theory to our mixed action setup, and outline the results. We explain our present fitting strategy, and give some preliminary results. Comment: 7 pages, 4 figures, Lattice 2008 proceeding
• Source
##### Article: Determination of $B_K$ using improved staggered fermions (II) SU(2) chiral perturbation theory fit
[Hide abstract]
ABSTRACT: We present results for $B_K$ calculated using HYP-smeared improved staggered fermions on the MILC asqtad lattices. In this report, the data is analyzed using the results of SU(2) staggered chiral perturbation theory (SChPT). We outline the derivation of the NLO SU(2) SChPT result, explain our fitting procedure, and outline how we estimate systematic errors. We also show the light sea-quark mass and lattice spacing dependence for both SU(2) and SU(3)-based analyses. Our preliminary result from the SU(2) analysis is $B_K(\text{NDR}, \mu = 2 \text{GeV}) = 0.512 \pm 0.014 \pm 0.034$ and $\hat{B}_K = B_K(\text{RGI})= 0.701 \pm 0.019 \pm 0.047$. This is somewhat more accurate than our result from the SU(3) analysis. It is consistent with results obtained using valence domain-wall fermions Comment: 7 pages, 6 figures, Lattice 2009 proceeding
• Source
##### Article: B_ {K} using HYP-smeared staggered fermions in N_ {f}= 2+ 1 unquenched QCD
[Hide abstract]
ABSTRACT: We present results for the kaon mixing parameter BK calculated using HYP (hypercubic fat link)-smeared improved staggered fermions on the asqtad lattices generated by the MILC collaboration. We use three lattice spacings (a≈0.12, 0.09 and 0.06 fm), ten different valence-quark masses (m≈ms/10-ms), and several light sea-quark masses in order to control the continuum and chiral extrapolations. We derive the next-to-leading order staggered chiral perturbation theory (SChPT) results necessary to fit our data, and use these results to do extrapolations based both on SU(2) and SU(3) SChPT. The SU(2) fitting is particularly straightforward because parameters related to taste breaking and matching errors appear only at next-to-next-to-leading order. We match to the continuum renormalization scheme [naïve dimensional regularization (NDR)] using one-loop perturbation theory. Our final result is from the SU(2) analysis, with the SU(3) result providing a (less accurate) cross check. We find BK(NDR,μ=2 GeV)=0.529±0.009±0.032 and B̂K=BK(RGI)=0.724±0.012±0.043, where the first error is statistical and the second systematic. The error is dominated by the truncation error in the matching factor. Our results are consistent with those obtained using valence domain-wall fermions on lattices generated with asqtad or domain-wall sea quarks.
Physical Review D 12/2010; 82(11). DOI:10.1103/PhysRevD.82.114509 · 4.64 Impact Factor