Results for quenched B from JLQCD

Abstract

A report is presented on our continued effort to elucidate the continuum limit of BK using the quenched Kogut-Susskind quark action. By adding to our previous simulations one more point at β = 6.65 employing a 56 3 × 96 lattice, we now confirm the expected O(a 2 ) behavior of BK with the Kogut-Susskind action. A simple continuum extrapolation quadratic in a leads to BK (NDR, 2 GeV) = 0.598(5). As our final value of BK in the continuum we present BK (NDR, 2 GeV)=0.628(42), as obtained by a fit including an α M S (1/a) 2 term arising from the lattice-continuum matching with the one-loop renormalization.

Unquenched QCD simulation results

“…Throughout Table 1 Summary of recent unquenched QCD simulations action a(fm) La (fm) m PS /m V N f = 2 PW [10] 0.086 1.4 0.69-0.83 PW [11] 0.086 2.0 0.55, 0.7 PKS [12] 0.09 1.5 0.57-0.70 PKS [13] 0.10-0.32 2.4-3.8 0.3-0.8 PC(1.76) [14] 0.12 1.0-1.9 0.67-0.86 RC(TP) [15] 0.11-0.22 2.5-2.6 0.55-0.81 PC(NP) [16] 0.10 1.6 0.58-0.83 PC(NP) [17] 0.10 1.2-2.0 0.60-0.80 N f = 3 SKS(I) [18] 0.14 2.8 0. 50-0.94 this paper, the following abbreviations are used to distinguish different lattice actions in simulations.…”

“…While finite size effects on hadron masses are known to be much stronger in unquenched QCD [22,23] and clover(right) [14,17] quark actions.…”

“…than in quenched QCD for the KS quark action [22,23], recent unquenched simulations [14,17] suggest that finite size effects for Wilson-type quark actions are milder.…”

“…Relative errors, (m H (L) − m H )/m H , for H= PS(Pseudo Scalar), V(Vector) and N(Nucleon), are plotted as a function of L in Fig. 2, at a ≃ 0.09 fm and m PS /m V ≃ 0.68 for the KS quark action [22,23] and at a ≃ 0.12 fm and m PS /m V ≃ 0.72 for the clover quark action [14,17]. At similar lattice spacings and m PS /m V , the size effect seems to be larger for the KS quark.…”

“…This assumption is correct at the lowest order of chiral perturbation theory and is well-satisfied numerically in data of ref. [17].…”