Improved determination of $B_K$ with staggered quarks

Abstract

We present results for the kaon mixing parameter $B_K$ obtained using improved staggered fermions on a much enlarged set of MILC asqtad lattices. Compared to our previous publication, which was based largely on a single ensemble at each of the three lattice spacings $a\approx 0.09$fm, $0.06$fm and $0.045$fm, we have added seven new fine and four new superfine ensembles, with a range of values of the light and strange sea-quark masses. We have also increased the number of measurements on one of the original ensembles. This allows us to do controlled extrapolations in the light and strange sea-quark masses, which we do simultaneously with the continuum extrapolation. This reduces the extrapolation error and improves the reliability of our error estimates. Our final result is ${\hat{B}}_K=0.7379\pm 0.0047(\text{stat})\pm 0.0365(\text{sys})$.

6 pages, 5 tables, 2 figures, updated references

References in corpus (3)

• $B_K$ using HYP-smeared staggered fermions in $N_f=2+1$ unquenched QCD
• Finite volume effects in $B_K$ with improved staggered fermions
• One-loop matching of improved four-fermion staggered operators with an improved gluon action

Cited by in corpus (12)

• FLAG Review 2019
• FLAG Review 2021
• ΔS=2 and ΔC=2 bag parameters in the SM and beyond from Nf=2+1+1 twisted-mass LQCD
• FLAG Review 2024
• Heavy physics contributions to neutrinoless double beta decay from QCD
• Kaon BSM B-parameters using improved staggered fermions from $N_f=2+1$ unquenched QCD
• Upper Bounds on epsilon'/epsilon Parameters B_6^{(1/2)} and B_8^{(3/2)} from Large N QCD and other News
• Lattice QCD Inputs for Nuclear Double Beta Decay
• Standard Model evaluation of ${\epsilon }_K$ using lattice QCD inputs for ${\hat{B}}_K$ and $V_{cb}$
• Modelling theoretical uncertainties in phenomenological analyses for particle physics
• Large N Approach to Kaon Decays and Mixing 28 Years Later: Delta I = 1/2 Rule, \hat B_K and Delta M_K
• Quark Flavor Physics Review