Beyond the Standard Model B-parameters with improved staggered fermions in $N_f=2+1$ QCD

Abstract

We calculate the kaon mixing B-parameters for operators arising generically in theories of physics beyond the standard model. We use HYP-smeared improved staggered fermions on the $N_f=2+1$ MILC asqtad lattices. Operator matching is done perturbatively at one-loop order. Chiral extrapolations are done using "golden combinations" in which one-loop chiral logarithms are absent. For the combined sea-quark mass and continuum extrapolation, we use three lattice spacings: $a\approx 0.045,0.06$ and $0.09\text{fm}$. Our results have a total error of 5-6%, which is dominated by the systematic error from matching and continuum extrapolation. For two of the BSM $B$-parameters, we agree with results obtained using domain-wall and twisted-mass dynamical fermions, but we disagree by $(4-5)\sigma$ for the other two.

7 pages, 5 figures, Lattice 2013 Proceeding

References in corpus (2)

• Neutral kaon mixing from new physics: matrix elements in $N_f=2+1$ QCD
• One-loop matching of improved four-fermion staggered operators with an improved gluon action

Cited by in corpus (2)

• Quark Flavor Physics Review
• $K$ and $D$ oscillations in the Standard Model and its extensions from $N_f=2+1+1$ Twisted Mass LQCD