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Contributions of strange quarks to the mass and spin of the nucleon, characterized by the observables f_Ts and Delta s, respectively, are investigated within lattice QCD. The calculation employs a 2+1-flavor mixed-action lattice scheme, thus treating the strange quark degrees of freedom in dynamical fashion. Numerical results are obtained at three pion masses, m_pi = 495 MeV, 356 MeV, and 293 MeV, renormalized, and chirally extrapolated to the physical pion mass. The value extracted for Delta s at the physical pion mass in the MSbar scheme at a scale of 2 GeV is Delta s = -0.031(17), whereas the strange quark contribution to the nucleon mass amounts to f_Ts =0.046(11). In the employed mixed-action scheme, the nucleon valence quarks as well as the strange quarks entering the nucleon matrix elements which determine f_Ts and Delta s are realized as domain wall fermions, propagators of which are evaluated in MILC 2+1-flavor dynamical asqtad quark ensembles. The use of domain wall fermions leads to mild renormalization behavior which proves especially advantageous in the extraction of f_Ts.
We perform a high statistics calculation of disconnected fermion loops on Graphics Processing Units for a range of nucleon matrix elements extracted using lattice QCD. The isoscalar electromagnetic and axial vector form factors, the sigma-terms and t
We calculate the strange quark content of the nucleon in 2+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 sca
Previous extrapolations of lattice QCD results for the nucleon mass to the physically relevant region of small quark masses, using chiral effective field theory, are extended and expanded in several directions. A detailed error analysis is performed.
We report a calculation of the nucleon axial form factors $G_A^q(Q^2)$ and $G_P^q(Q^2)$ for all three light quark flavors $qin{u,d,s}$ in the range $0leq Q^2lesssim 1.2text{ GeV}^2$ using lattice QCD. This work was done using a single ensemble with p
We determine the strange and light quark condensates in full lattice QCD for the first time. This is done by direct calculation of the expectation value of the trace of the quark propagator followed by subtraction of the appropriate perturbative cont