scholarly journals Chiral Corrections for Lattice QCD

1991 ◽  
Vol 44 (3) ◽  
pp. 173 ◽  
Author(s):  
Anthony W Thomas
Keyword(s):  
Lattice Qcd ◽  
Quark Mass ◽  
Mass Splitting ◽  
Residual Error ◽  
Similar Amount ◽  
Nucleon Mass ◽  
Systematic Method ◽  
Lattice Size

We show that in the quenched approximation, lattice QCD calculations miss important corrections to the mass of hadrons. For example, we argue that the nucleon mass is overestimated by up to 30% while the nucleon-delta mass splitting is underestimated by a similar amount. As the quenched approximation is relaxed, the quark mass decreased and the lattice size increased, these errors should go away. A systematic method of monitoring the size of the residual error is suggested.

scholarly journals The Sigma Term: Leading Non-Analytic Behaviour Of Decuplet Contributions

1994 ◽  
Vol 47 (1) ◽  
pp. 45 ◽  
Author(s):  
I Jameson ◽  
AA Rawlinson ◽  
AW Thomas
Keyword(s):  
Quark Mass ◽  
Mass Splitting ◽  
Analytic Structure ◽  
Nucleon Mass ◽  
Sigma Term ◽  
Pion Nucleon ◽  
Analytic Behaviour

We examine the analytic structure, in powers of the quark mass (m), of the chiral loop corrections to the pion-nucleon sigma term arising from coupling to the lowest mass baryon decuplet. The leading non-analytic term is found to go like m2 In(m/2a) (with a the delta-nucleon mass splitting), and to be quite significant numerically.

scholarly journals Double parton distributions in the pion from lattice QCD

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Gunnar S. Bali ◽  
Luca Castagnini ◽  
Markus Diehl ◽  
Jonathan R. Gaunt ◽  
Benjamin Gläßle ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Lattice Qcd ◽  
Quark Mass ◽  
Matrix Elements ◽  
Parton Distributions ◽  
Almost All ◽  
The Relationship

Abstract We perform a lattice study of double parton distributions in the pion, using the relationship between their Mellin moments and pion matrix elements of two local currents. A good statistical signal is obtained for almost all relevant Wick contractions. We investigate correlations in the spatial distribution of two partons in the pion, as well as correlations involving the parton polarisation. The patterns we observe depend significantly on the quark mass. We investigate the assumption that double parton distributions approximately factorise into a convolution of single parton distributions.

scholarly journals Isospin-1/2 Dπ scattering and the lightest $$ {D}_0^{\ast } $$ resonance from lattice QCD

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Luke Gayer ◽  
Nicolas Lang ◽  
Sinéad M. Ryan ◽  
David Tims ◽  
Christopher E. Thomas ◽  
...  
Keyword(s):  
Scattering Amplitudes ◽  
Lattice Qcd ◽  
Quark Mass ◽  
Light Quark ◽  
Energy Levels ◽  
Experimental Result ◽  
Infinite Volume ◽  
Resonance Pole ◽  
Strongly Coupled ◽  
Light Quark Mass

Abstract Isospin-1/2 Dπ scattering amplitudes are computed using lattice QCD, working in a single volume of approximately (3.6 fm)3 and with a light quark mass corresponding to mπ ≈ 239 MeV. The spectrum of the elastic Dπ energy region is computed yielding 20 energy levels. Using the Lüscher finite-volume quantisation condition, these energies are translated into constraints on the infinite-volume scattering amplitudes and hence enable us to map out the energy dependence of elastic Dπ scattering. By analytically continuing a range of scattering amplitudes, a $$ {D}_0^{\ast } $$ D 0 ∗ resonance pole is consistently found strongly coupled to the S-wave Dπ channel, with a mass m ≈ 2200 MeV and a width Γ ≈ 400 MeV. Combined with earlier work investigating the $$ {D}_{s0}^{\ast } $$ D s 0 ∗ , and $$ {D}_0^{\ast } $$ D 0 ∗ with heavier light quarks, similar couplings between each of these scalar states and their relevant meson-meson scattering channels are determined. The mass of the $$ {D}_0^{\ast } $$ D 0 ∗ is consistently found well below that of the $$ {D}_{s0}^{\ast } $$ D s 0 ∗ , in contrast to the currently reported experimental result.

scholarly journals Chiral Fermions Algorithms In Lattice QCD

2019 ◽  
Keyword(s):  
Lattice Qcd ◽  
Quark Mass ◽  
Optimal Algorithm ◽  
Quark Propagator ◽  
Critical Slowing Down ◽  
Group Symmetry ◽  
Inversion Algorithm ◽  
Four Dimensions ◽  
Slowing Down ◽  
Lattice Gauge

The theory that explains the strong interactions of the elementary particles, as part of the standard model, it is the so-called Quantum Chromodynamics (QCD) theory. In regimes of low energy this theory it is formulated and solved in a lattice with four dimensions using numerical simulations. This method it is called the lattice QCD theory. Quark propagator it the most important element that is calculated because it contains the physical information of lattice QCD. Computing quark propagator of chiral fermions in lattice means that we should invert the chiral Dirac operator, which has high complexity. In the standard inversion algorithms of the Krylov subspace methods, that are used in these kinds of simulations, the time of inversion is scaled with the inverse of the quark mass. In lattice QCD simulations with chiral fermions, this phenomenon it is knowing as the critical slowing-down problem. The purpose of this work is to show that the preconditioned GMRESR algorithm, developed in our previous work, solves this problem. The preconditioned GMRESR algorithm it is developed in U(1) group symmetry using QCDLAB 1.0 package, as good “environment” for testing new algorithms. In this paper we study the escalation of the time of inversion with the quark mass for this algorithm. It turned out that it is a fast inversion algorithm for lattice QCD simulations with chiral fermions, that “soothes” the critical slowing-down of standard algorithms. The results are compared with SHUMR algorithm that is optimal algorithm used in these kinds of simulations. The calculations are made for 100 statistically independent configurations on 64 x 64 lattice gauge U(1) field for three coupling constant and for some quark masses. The results showed that for the preconditioned GMRESR algorithm the coefficient k, related to the critical slowing down phenomena, it is approximately - 0.3 compared to the inverse proportional standard law (k = -1) that it is scaled SHUMR algorithm, even for dense lattices. These results make more stable and confirm the efficiency of our algorithm as an algorithm that avoid the critical slowing down phenomenon in lattice QCD simulations. In our future studies we have to develop the preconditioned GMRESR algorithm in four dimensions, in SU (3) lattice gauge theory.

scholarly journals The nucleon mass in Nf=2 lattice QCD: finite size effects from chiral perturbation theory

2004 ◽  
Vol 689 (3) ◽  
pp. 175-194 ◽  
Author(s):  
A. Ali Khan ◽  
T. Bakeyev ◽  
M. Göckeler ◽  
T.R. Hemmert ◽  
R. Horsley ◽  
...  
Keyword(s):  
Perturbation Theory ◽  
Lattice Qcd ◽  
Chiral Perturbation Theory ◽  
Size Effects ◽  
Finite Size ◽  
Nucleon Mass ◽  
Chiral Perturbation ◽  
Finite Size Effects

THE ρ0-ρ± ELECTROMAGNETIC MASS SPLITTING

2002 ◽  
Vol 17 (11) ◽  
pp. 659-666 ◽  
Author(s):  
DAO-NENG GAO ◽  
MU-LIN YAN
Keyword(s):  
Theoretical Prediction ◽  
Mass Splitting ◽  
Electromagnetic Mass ◽  
Systematic Method ◽  
The One

A systematic method developed by us to evaluate the one-loop electromagnetic self-energies of the low-lying mesons is extended to the case of the ρ-meson. The theoretical prediction of ρ0-ρ± electromagnetic mass splitting is about 0.62 MeV, which is in agreement with the measurements.

The goldstone pion in SU(2) lattice QCD at low quark mass: Scaling and finite size effects

1986 ◽  
Vol 271 (2) ◽  
pp. 461-496 ◽  
Author(s):  
A. Billoire ◽  
R. Lacaze ◽  
E. Marinari ◽  
A. Morel
Keyword(s):  
Lattice Qcd ◽  
Size Effects ◽  
Quark Mass ◽  
Finite Size ◽  
Finite Size Effects ◽  
Mass Scaling

scholarly journals THE NUCLEON MASS AND PION-NUCLEON SIGMA TERM FROM A CHIRAL ANALYSIS OF Nf = 2 + 1 LATTICE QCD WORLD DATA

2014 ◽  
Vol 26 ◽  
pp. 1460089 ◽  
Author(s):  
L. ALVAREZ-RUSO ◽  
T. LEDWIG ◽  
M. J. VICENTE VACAS ◽  
J. MARTIN-CAMALICH
Keyword(s):  
Lattice Qcd ◽  
Degrees Of Freedom ◽  
Pion Mass ◽  
Nucleon Mass ◽  
A Value ◽  
Natural Size ◽  
Sigma Term ◽  
Pion Nucleon ◽  
Pion Mass Dependence ◽  
Energy Constants

Fits of the p4 covariant SU(2) baryon chiral perturbation theory to lattice QCD nucleon mass data from several collaborations for 2 and 2+1 flavors are presented. We consider contributions from explicit Δ(1232) degrees of freedom, finite volume and finite spacing corrections. We emphasize here on our Nf = 2 + 1 study. We obtain low-energy constants of natural size that are compatible with the rather linear pion-mass dependence of the nucleon mass observed in lattice QCD. We report a value of σπN = 41(5)(4) MeV in the 2 flavor case and σπN = 52(3)(8) MeV for 2+1 flavors.

scholarly journals Up Quark Mass in Lattice QCD with Three Light Dynamical Quarks and Implications for StrongCPInvariance

2003 ◽  
Vol 90 (2) ◽  
Author(s):  
Daniel R. Nelson ◽  
George T. Fleming ◽  
Gregory W. Kilcup
Keyword(s):  
Lattice Qcd ◽  
Quark Mass ◽  
Up Quark
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