Singlet versus nonsinglet perturbative renormalization of fermion bilinears

Constantinou, Martha; Hadjiantonis, Marios; Panagopoulos, H.; Spanoudes, Gregoris

doi:10.1103/physrevd.94.114513

Cited by 35 publications

(46 citation statements)

References 35 publications

(47 reference statements)

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“…The disconnected contribution to Z A0 may be non-negligible, but is ignored in this study. We note that such contribution turns out to be not large ( 5 %) in a perturbative analysis for the Wilson-type fermions [44][45][46]. The nonperturbative estimate for the twisted mass fermions gives Z A3 = 0.7910(4)(5) and Z A0 = 0.7968(25)(91) [47,48], a discrepancy which is consistent with zero within the error bar.…”

Section: Renormalization and Chiral Symmetrymentioning

confidence: 77%

Nucleon charges with dynamical overlap fermions

et al. 2018

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We calculate the scalar and tensor charges of the nucleon in 2+1-flavor lattice QCD, for which the systematics of the renormalization of the disconnected diagram is well controlled. Numerical simulations are performed at a single lattice spacing a = 0.11 fm. We simulate four pion masses, which cover a range of m π ∼ 290 -540 MeV, and a single strange quark mass close to its physical value. The statistical accuracy is improved by employing the so-called low-mode averaging technique and the truncated solver method. We study up, down, and strange quark contributions to the nucleon charges by calculating disconnected diagrams using the all-to-all quark propagator.Chiral symmetry is exactly preserved by using the overlap quark action to avoid operator mixing among different flavors, which complicates the renormalization of scalar and tensor matrix elements and leads to possibly large contamination to the small strange quark contributions. We also study the nucleon axial charge with a contribution from the disconnected diagram. Our results are in reasonable agreement with experiments and previous lattice studies.

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Section: Renormalization and Chiral Symmetrymentioning

confidence: 77%

Nucleon charges with dynamical overlap fermions

et al. 2018

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“…VI. Their difference is known to be very small as it first appears in two-loop perturbation theory [85]. Here, we calculate also the singlet renormalization function nonperturbatively, which requires both connected and disconnected contributions to the vertex functions.…”

Section: A Quark Emt Renormalizationmentioning

confidence: 99%

Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass

et al. 2020

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We evaluate the gluon and quark contributions to the spin of the proton using an ensemble of gauge configurations generated at physical pion mass. We compute all valence and sea quark contributions to high accuracy. We perform a nonperturbative renormalization for both quark and gluon matrix elements. We find that the contribution of the up, down, strange, and charm quarks to the proton intrinsic spin is 1 2 P q¼u;d;s;c ΔΣ q þ ¼ 0.191ð15Þ and to the total spin P q¼u;d;s;c J q þ ¼ 0.285ð45Þð10Þ. The gluon contribution to the spin is J g ¼ 0.187ð46Þð10Þ yielding J ¼ J q þ J g ¼ 0.473ð71Þð14Þ confirming the spin sum. The momentum fraction carried by quarks in the proton is found to be 0.618(60) and by gluons 0.427(92), the sum of which gives 1.045(118) confirming the momentum sum rule. All scale and scheme dependent quantities are given in the MS scheme at 2 GeV.

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“…The difference between Z isovector and Z isoscalar for quark bilinear operators starts, in general, at two loops in perturbation theory. For the tensor operator, the two-loop terms are zero because the spin trace vanishes in the clover, HISQ, and thus clover-on-HISQ formulations [14]. Also, for the twisted mass action, nonperturbative calculations show Z isovector…”

Section: Renormalization Of the Operatorsmentioning

confidence: 99%

Flavor diagonal tensor charges of the nucleon from ( 2+1+1 )-flavor lattice QCD

et al. 2018

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We present state-of-the-art results for the matrix elements of flavor diagonal tensor operators within the nucleon state. The calculation of the dominant connected contribution is done using eleven ensembles of gauge configurations generated by the MILC Collaboration using the highly improved staggered quark (HISQ) action with 2+1+1 dynamical flavors. The calculation of the disconnected contributions is done using seven (six) ensembles for the strange (light) quarks. These high-statistics simulations allowed us to address various systematic uncertainties. A simultaneous fit in the lattice spacing and the light-quark mass is used to extract the tensor charges in the continuum limit and at Mπ = 135 MeV. Results for the proton in the M S scheme at 2 GeV are: g u T = 0.784(28)(10), g d T = −0.204(11)(10) and g s T = −0.0027(16). Implications of these results for constraining the quark electric dipole moments and their contributions to the neutron electric dipole moment are discussed.

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Singlet versus nonsinglet perturbative renormalization of fermion bilinears

Cited by 35 publications

References 35 publications

Nucleon charges with dynamical overlap fermions

Nucleon charges with dynamical overlap fermions

Complete flavor decomposition of the spin and momentum fraction of the proton using lattice QCD simulations at physical pion mass

Flavor diagonal tensor charges of the nucleon from ( 2+1+1 )-flavor lattice QCD

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