P o S ( L A T 2 0 0 6 ) 1 1 8 Nucleon structure in lattice QCD with dynamical domain-wall fermion quarks (original) (raw)
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Nucleon structure in lattice QCD with dynamical domain-wall fermions quarks
We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with about 200 gauge configurations each. The lattice cutoff is about 1.7 GeV and the spatial volume is about (1.9 fm)^3. Despite the small volume, the ratio of the isovector vector and axial charges g_A/g_V and that of structure function moments _{u-d}/ _{Delta u - Delta d} are in agreement with experiment, and show only very mild quark mass dependence. The second, RBC/UK, set of ensembles employs one strange and two degenerate (up and down) dynamical DWF quarks and Iwasaki gauge action. The strange quark mass is set at 0.04, and three up/down mass values of 0.03, 0.02 and 0.01 in lattice units are used. The lattice cutoff is about 1.6 GeV ...
Nucleon structure from lattice QCD with domain wall fermions quarks
Bulletin of the American Physical Society, 2005
We report the current status of RBCK calculations on nucleon structure with both quenched and unquenched lattice &CD. The combination of domain wall fermions and DBW2 gauge action works well for quantities like isovector vector and axial charges, moments of structure functions (ST),, dl, and (l)ap, and nucleon decay matrix elements. Good chiral symmetry is observed, and translates into continuum-like behavior of non-perturabtive renormalization where explicitly checked. Pion form factor calculation in the same framework is also reported.
Lattice QCD with two dynamical flavors of domain wall quarks
Physical Review D, 2004
We present results from the first large-scale study of two flavor QCD using domain wall fermions (DWF), a chirally symmetric fermion formulation which has proven to be very effective in the quenched approximation. We work on lattices of size 16^3x32, with a lattice cut-off of a^{-1}\approx 1.7 GeV, and dynamical (or sea) quark masses in the range m_{strange}/2 \simle m_{sea} \simle m_{strange}. After discussing the algorithmic and implementation issues involved in simulating dynamical DWF, we report on the low-lying hadron spectrum, decay constants, static quark potential, and the important kaon weak matrix element describing indirect CP violation in the Standard Model, B_K. In the latter case we include the effect of non-degenerate quark masses (m_s \neq m_u = m_d), finding B_K(MS-bar, 2 GeV) = 0.495(18).
Nucleon structure with dynamical (2+1)-flavor domain wall fermions lattice QCD
We report isovector form factors and low moments of isovector structure functions of nucleon from the coarse RIKEN-BNL-Columbia (RBC) and UKQCD joint dynamical (2+1)-flavor domain-wall fermions (DWF) ensembles. The lattice cut off is estimated at (a^{-1}=1.7) GeV. The lattice volume is as large as 2.7 fm across. We carefully optimize the nucleon source/sink separation in time to about 1.4 fm. Unexpectedly large finite-size effect in the axial charge is found. The effect scales with a single variable, the product (m_\pi L) of the pion mass (m_\pi) and lattice spatial linear extent (L), and sets in at around (m_\pi L = 5). We also discuss momentum-transfer dependence of the vector, induced tensor, axial-vector and induced pesudo-scalar form factors. From structure functions, fully non-perturbatively renormalized iso-vector quark momentum fraction, (< x >_{u-d}), helicity fraction, (< x >_{\Delta u - \Delta d}), and transversity, (< 1 >_{\delta u - \delta d}), are rep...
Nucleon structure from 2+1f dynamical DWF lattice QCD at nearly physical pion mass
Proceedings of XXIX International Symposium on Lattice Field Theory — PoS(Lattice 2011)
Current status of nucleon structure calculations with joint RBC and UKQCD 2+1-flavor dynamical domain-wall fermions (DWF) lattice QCD is reported: Two ensembles with pion mass of about m π = 170 MeV and 250 MeV are used. The lattice cutoff is set at about 1.4 GeV, allowing a large spatial volume of about L = 4.6 fm across while maintaining a sufficiently small residual breaking of chiral symmetry with the dislocation-suppressing-determinant-ratio (DSDR) gauge action. We calculate all the isovector form factors and some low moments of isovector structure functions. We confirm the finite-size effect in isovector axialvector-current form factors, in particular the deficit in the axial charge and its scaling in terms of m π L, that we reported from our earlier calculation at heavier pion masses.
Nucleon structure from lattice QCD with domain wall fermions
Nuclear Physics B - Proceedings Supplements, 2004
We report the current status of RBCK calculations on nucleon structure with both quenched and unquenched lattice &CD. The combination of domain wall fermions and DBW2 gauge action works well for quantities like isovector vector and axial charges, moments of structure functions (ST),, dl, and (l)ap, and nucleon decay matrix elements. Good chiral symmetry is observed, and translates into continuum-like behavior of non-perturabtive renormalization where explicitly checked. Pion form factor calculation in the same framework is also reported.
Nucleon structure from 2+1 -flavor dynamical DWF lattice QCD at nearly physical pion mass
Progress in Particle and Nuclear Physics, 2012
Domain-wall fermions (DWF) is a lattice discretization for Dirac fields that preserves continuumlike chiral and flavor symmetries that are essential in hadron physics. RIKEN-BNL-Columbia (RBC) and UKQCD Collaborations have been generating sets of realistic 2+1-flavor dynamical lattice quantum chromodynamics (QCD) numerical ensembles with DWF quarks with strange mass set almost exactly at its physical value via reweighing and degenerate up and down mass set as light as practical. In this report the current status of the nucleon-structure calculations using these ensembles are summarized.
Proceedings of The 32nd International Symposium on Lattice Field Theory — PoS(LATTICE2014)
Analyses on possible systematics in some isovector nucleon observables in the RBC+UKQCD 2+1-flavor dynamical domain-wall fermion (DWF) lattice-QCD are presented. The vector charge, axial charge, quark momentum and helicity fractions, and transversity are discussed using mainly the Iwasaki×DSDR ensemble at pion mass of 170 MeV. No autocorrelation issue is observed in the vector charge and quark momentum and helicity fractions. Blocked Jack-knife analyses expose significant growth of estimated error for the axial charge with increasing block sizes that are similar to or larger than the known autocorrelation time of the gauge-field topological charge. Similar growth is seen in the transversity. These two observables, however, do not seem correlated with the topological charge.
Nucleon structure functions from dynamical (2+1)-flavor domain wall fermions
Proceedings of The XXVI International Symposium on Lattice Field Theory — PoS(LATTICE 2008)
We report lattice-volume independence of low moments of nucleon structure functions from the coarse RIKEN-BNL-Columbia (RBC) and UKQCD joint dynamical (2+1)-flavor domain-wall fermions (DWF) ensembles at the lattice cut off of a −1 ∼ 1.7 GeV. The isovector quark momentum fraction, x u−d , and helicity fraction, x ∆u−∆d , both fully non-perturbatively renormalized are studied on two spatial volumes of (∼ 2.7fm) 3 and (∼ 1.8fm) 3. Their naturally renormalized ratio, x u−d / x ∆u−∆d , is not affected by any finite-size effect. It does not depend strongly on light quark mass and does agree well with the experiment. The respective absolute values, fully non-perturbatively renormalized, do not show any finite-size effect either. They show trending toward the respective experimental values at the lightest up-and down-quark mass. This trending down to the experimental values appears to be a real physical effect driven by lighter quarks. The observations are in contrast to the huge finite-size effect seen in the axial-current form factors.
Lattice QCD with two dynamical flavors of domain wall fermions
Physical Review D, 2005
We present results from the first large-scale study of two flavor QCD using domain wall fermions (DWF), a chirally symmetric fermion formulation which has proven to be very effective in the quenched approximation. We work on lattices of size 16 3 × 32, with a lattice cut-off of a −1 ≈ 1.7 GeV, and dynamical (or sea) quark masses in the range m strange /2 < ∼ m sea < ∼ m strange . After discussing the algorithmic and implementation issues involved in simulating dynamical DWF, we report on the low-lying hadron spectrum, decay constants, static quark potential, and the * Present address: 2 important kaon weak matrix element describing indirect CP violation in the Standard Model, B K . In the latter case we include the effect of non-degenerate quark masses (m s = m u = m d ), finding B M S K (2 GeV) = 0.495 (18).