Nucleon strange quark content fromNf=2+1lattice QCD with exact chiral symmetry

Abstract

We calculate the strange quark content of the nucleon hNj" ssjNi in 2 þ 1 -flavor lattice QCD. Chirally symmetric overlap fermion formulation is used to avoid the contamination from up and down quark contents due to an operator mixing between strange and light scalar operators, " ss and " uu þ " dd. At a lattice spacing a ¼ 0:112ð1Þ fm, we perform calculations at four values of degenerate up and down quark masses m ud , which cover a range of the pion mass M ' 300-540 MeV. We employ two different methods to calculate hNj" ssjNi. One is a direct method where we calculate hNj" ssjNi by directly inserting the " ss operator. The other is an indirect method where hNj" ssjNi is extracted from a derivative of the nucleon mass in terms of the strange quark mass. With these two methods we obtain consistent results for hNj" ssjNi with each other. Our best estimate f T s ¼ m s hNj" ssjNi=M N ¼ 0:009ð15Þ stat ð16Þ sys is in good agreement with our previous studies in two-flavor QCD.

QCD effects on direct detection of wino dark matter

“…The effective Lagrangian comprises two types of the higher dimension operators -the scalar and the twist-2 type operators -as follows [84]: Table 1. Mass fractions computed with the lattice simulations of QCD [89,90].…”

“…They are taken from ref. [74], which are computed with the recent results of the lattice QCD simulations [89,90]. The nucleon matrix element of O G S , on the other hand, is evaluated by means of the trace anomaly of the energy-momentum tensor in QCD [91]:…”

Strangeness of the nucleon from lattice QCD

“…There are a number of lattice works that concentrate on the determination of σ s using direct and/or indirect computation (see for instance [22][23][24][25] for N f ¼ 2 þ 1 results). Other lattice works for N f ¼ 2 þ 1 provide indirect determinations of y N [26][27][28][29] and our result for y N is in agreement with these works.…”

Linear programming analysis of the R-parity violation within EDM-constraints

“…favored by lattice QCD studies [166][167][168][169][170][171][172][173][174][175][176][177][178][179][180] and the isovector content p|ūu−dd|p ≈ 1.02, also derived from the analysis of several lattice QCD results [184][185][186][187]. The strange quark content was given by the lattice QCD studies [166][167][168][169][170][171][172][173][174][175][176][177][178][179][180][181][182].…”

“…The strange quark content was given by the lattice QCD studies [166][167][168][169][170][171][172][173][174][175][176][177][178][179][180][181][182]. The quark masses that we use are [163] m u = 2.2 MeV, (2.24)…”