scholarly journals The continuum limit of the quark mass step scaling function in quenched lattice QCD

2004 ◽  
Vol 2004 (05) ◽  
pp. 001-001 ◽  
Author(s):  
M Guagnelli ◽  
J Heitger ◽  
F Palombi ◽  
C Pena ◽  
A Vladikas
Keyword(s):  
Lattice Qcd ◽  
Quark Mass ◽  
Continuum Limit ◽  
Scaling Function ◽  
The Continuum

scholarly journals Topological susceptibility with a single light quark flavour

2018 ◽  
Vol 175 ◽  
pp. 14017 ◽  
Author(s):  
Julien Frison ◽  
Ryuichiro Kitano ◽  
Norikazu Yamada
Keyword(s):  
Quark Mass ◽  
Continuum Limit ◽  
Light Quark ◽  
The Other ◽  
Theoretical Argument ◽  
Up Quark ◽  
Order Of Magnitude ◽  
Quark Flavour ◽  
Definition Of ◽  
The Continuum

One of the historical suggestions to tackle the strong CP problem is to take the up quark mass to zero while keeping md finite. The θ angle is then supposed to become irrelevant, i.e. the topological susceptibility vanishes. However, the definition of the quark mass is scheme-dependent and identifying the mu = 0 point is not trivial, in particular with Wilson-like fermions. More specifically, up to our knowledge there is no theoretical argument guaranteeing that the topological susceptibility exactly vanishes when the PCAC mass does. We will present our recent progresses on the empirical check of this property using Nf = 1 + 2 flavours of clover fermions, where the lightest fermion is tuned very close to [see formula in PDF] and the mass of the other two is kept of the order of magnitude of the physical ms. This choice is indeed expected to amplify any unknown non-perturbative effect caused by mu ≠ md. The simulation is repeated for several βs and those results, although preliminary, give a hint about what happens in the continuum limit.

scholarly journals Flavor singlet meson mass in the continuum limit in two-flavor lattice QCD

2003 ◽  
Vol 67 (7) ◽  
Author(s):  
V. I. Lesk ◽  
S. Aoki ◽  
R. Burkhalter ◽  
M. Fukugita ◽  
K.-I. Ishikawa ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
Meson Mass ◽  
The Continuum

CHIRALLY EXTENDED QUANTUM CHROMODYNAMICS

1995 ◽  
Vol 06 (05) ◽  
pp. 725-742 ◽  
Author(s):  
RICHARD C. BROWER ◽  
YUE SHEN ◽  
CHUNG-I TAN
Keyword(s):  
Quantum Chromodynamics ◽  
Quark Mass ◽  
Continuum Limit ◽  
Chiral Limit ◽  
Scalar Fields ◽  
Weak Coupling Limit ◽  
Slowing Down ◽  
Large N ◽  
Chiral Invariance ◽  
The Continuum

We propose an extended Quantum Chromodynamics (XQCD) Lagrangian in which the fermions are coupled to elementary scalar fields through a Yukawa coupling which preserves chiral invariance. Our principle motivation is to find a new lattice formulation for QCD which avoids the source of critical slowing down usually encountered as the bare quark mass is tuned to the chiral limit. The phase diagram and the weak coupling limit for XQCD are studied. They suggest a conjecture that the continuum limit of XQCD is the same as the continuum limit of conventional lattice formulation of QCD. As examples of such universality, we present the large N solutions of two prototype models for XQCD, in which the mass of the spurious pion and sigma resonance go to infinity with the cut-off. Even if the universality conjecture turns out to be false, we believe that XQCD will still be useful as a low energy effective action for QCD phenomenology on the lattice. Numerical simulations are recommended to further investigate the possible benefits of XQCD in extracting QCD predictions.

scholarly journals Heavy–light decay constants in the continuum limit of quenched lattice QCD

2003 ◽  
Vol 672 (1-2) ◽  
pp. 372-386 ◽  
Author(s):  
G.M. de Divitiis ◽  
M. Guagnelli ◽  
F. Palombi ◽  
R. Petronzio ◽  
N. Tantalo
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
Decay Constants ◽  
The Continuum

scholarly journals Lattice QCD calculation of the proton decay matrix element in the continuum limit

2004 ◽  
Vol 70 (11) ◽  
Author(s):  
N. Tsutsui ◽  
S. Aoki ◽  
M. Fukugita ◽  
S. Hashimoto ◽  
K-I. Ishikawa ◽  
...  
Keyword(s):  
Matrix Element ◽  
Lattice Qcd ◽  
Continuum Limit ◽  
Proton Decay ◽  
The Continuum ◽  
Decay Matrix Element

scholarly journals The scalar radius of the pion from lattice QCD in the continuum limit

2015 ◽  
Vol 51 (12) ◽  
Author(s):  
Vera Gülpers ◽  
Georg von Hippel ◽  
Hartmut Wittig
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
The Continuum

scholarly journals ABELIAN PROJECTION AND STUDIES OF GAUGE-VARIANT QUANTITIES IN THE LATTICE QCD WITHOUT GAUGE FIXING

1996 ◽  
Vol 11 (13) ◽  
pp. 1081-1093 ◽  
Author(s):  
SERGEI V. SHABANOV
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
Gluon Propagator ◽  
Lorentz Invariance ◽  
Gauge Condition ◽  
Gauge Fields ◽  
Gauge Invariant ◽  
Dynamical Reduction ◽  
Gauge Fixing ◽  
The Continuum

We suggest a new (dynamical) Abelian projection of the lattice QCD. It contains no gauge condition imposed on gauge fields so that Gribov copying is avoided. Configurations of gauge fields that turn into monopoles in the Abelian projection can be classified in a gauge-invariant way. In the continuum limit, the theory respects the Lorentz invariance. A similar dynamical reduction of the gauge symmetry is proposed for studies of gauge-variant correlators (like a gluon propagator) in the lattice QCD. Though the procedure is harder for numerical simulations, it is free of gauge-fixing artifacts, like the Gribov horizon and copies.

scholarly journals Charm sea effects on charmonium decay constants and heavy meson masses

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Salvatore Calì ◽  
Kevin Eckert ◽  
Jochen Heitger ◽  
Francesco Knechtli ◽  
Tomasz Korzec
Keyword(s):  
Lattice Qcd ◽  
Continuum Limit ◽  
Charm Quark ◽  
Heavy Meson ◽  
Charm Quarks ◽  
Decay Constants ◽  
Derivatives Of ◽  
Charm Mass ◽  
The Continuum

AbstractWe estimate the effects on the decay constants of charmonium and on heavy meson masses due to the charm quark in the sea. Our goal is to understand whether for these quantities $${N_\mathrm{f}}=2+1$$ N f = 2 + 1 lattice QCD simulations provide results that can be compared with experiments or whether $${N_\mathrm{f}}=2+1+1$$ N f = 2 + 1 + 1 QCD including the charm quark in the sea needs to be simulated. We consider two theories, $${N_\mathrm{f}}=0$$ N f = 0 QCD and QCD with $${N_\mathrm{f}}=2$$ N f = 2 charm quarks in the sea. The charm sea effects (due to two charm quarks) are estimated comparing the results obtained in these two theories, after matching them and taking the continuum limit. The absence of light quarks allows us to simulate the $${N_\mathrm{f}}=2$$ N f = 2 theory at lattice spacings down to 0.023 fm that are crucial for reliable continuum extrapolations. We find that sea charm quark effects are below 1% for the decay constants of charmonium. Our results show that decoupling of charm works well up to energies of about 500 MeV. We also compute the derivatives of the decay constants and meson masses with respect to the charm mass. For these quantities we again do not see a significant dynamical charm quark effect, albeit with a lower precision. For mesons made of a charm quark and a heavy antiquark, whose mass is twice that of the charm quark, sea effects are only about 1‰ in the ratio of vector to pseudoscalar masses.

THE CHIRAL U(1) SYMMETRY IN LATTICE QCD WITH WILSON FERMIONS

1995 ◽  
Vol 10 (15) ◽  
pp. 2269-2290 ◽  
Author(s):  
CARLO UNGARELLI
Keyword(s):  
Lattice Qcd ◽  
Chiral Symmetry ◽  
Continuum Limit ◽  
Axial Current ◽  
Numerical Results ◽  
Ward Identities ◽  
Definition Of ◽  
The Continuum ◽  
Wilson Fermions

The properties of singlet flavor chiral symmetry of lattice QCD with Wilson fermions are analyzed. We show that a suitable U(1) axial current can be defined, satisfying, in the continuum limit, the Adler-Bell-Jackiw anomaly. Moreover, the renormalization properties of composite operators which appear in U(1) chiral Ward identities are discussed. Finally, starting from the renormalized Ward identities for the axial U(1) current, we analyze a definition of topological susceptibility suitable for nonperturbative studies and discuss preliminary numerical results.

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