BKwith two flavors of dynamical overlap fermions

Abstract

We present a two-flavor QCD calculation of B K on a 16 3 × 32 lattice at a ∼ 0.12 fm (or equivalently a −1 =1.67 GeV). Both valence and sea quarks are described by the overlap fermion formulation. The matching factor is calculated nonperturbatively with the so-called RI/MOM scheme. We find that the lattice data are well described by the next-to-leading order (NLO) partially quenched chiral perturbation theory (PQChPT) up to around a half of the strange quark mass (m phys s /2). The data at quark masses heavier than m phys s /2 are fitted including a part of next-to-next-to-leading order terms. We obtain B MS K (2 GeV) = 0.537(4)(40), where the first error is statistical and the second is an estimate of systematic uncertainties from finite volume, fixing topology, the matching factor, and the scale setting.

Flavor physics in the quark sector

“…56. Summary of lattice results forB K : included are recent results from dynamical N f = 2 + 1 [110,[873][874][875] and N f = 2 [876,877] simulations. Also shown are quenched (N f = 0) results from JLQCD [882], RBC [883], and CP-PACS [884].…”

“…Results with N f = 2 are available from JLQCD [876] using dynamical overlap fermions and from ETMC [877] using twisted mass fermions, 21 both with nonperturbative renormalization. While ETMC also used Kaon SU(2)-ChPT, the JLQCD result was extrapolated using NLO SU(3)-ChPT with analytic NNLO-terms added.…”

BK-parameter fromNf=2twisted mass lattice QCD

“…A compilation of recent data is provided in Fig. 1 [4][5][6][7][8][9][10][11][12], respectively. The symbol ⋆ denotes determinations where the continuum extrapolation was carried out.…”

Kaon physics from lattice

“…JLQCD [49] made an impressive calculation with 2f overlap action, while ETMC used a somewhat less aesthetic mixed action approach with Osterwalder-Seiler valence fermions with 2f twisted mass sea fermions [50]. JLQCD obtained B MS K (n f = 2, 2GeV) = 0.537(4)(40) and ETMC obtained B MS K (n f = 2, 2GeV) = 0.56(2) both with single lattice spacings.…”

“…The four recent high quality 2f and 2+1f simulations [49,50,11,52,18] all make use of the Rome-Southamptom RI-mom scheme to match between lattice and the MS regularisation schemes via an intermediate physically defined MOM scheme.…”