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Lattice QED2 with the Wilson formulation of fermions is used as a convenient model system to study artifacts of the quenched approximation on a finite lattice. The quenched functional integral is shown to be ill-defined in this system as a…

High Energy Physics - Lattice · Physics 2009-10-30 W. Bardeen , A. Duncan , E. Eichten , H. Thacker

We explain how scale dependent renormalized quantities can be computed using lattice QCD. Two examples are used: the running coupling and quark masses. A reliable computation of the $\Lambda$-parameter in the quenched approximation is…

High Energy Physics - Phenomenology · Physics 2007-05-23 Rainer Sommer

Quasi-Newton (QN) methods provide an efficient alternative to second-order methods for minimizing smooth unconstrained problems. While QN methods generally compose a Hessian estimate based on one secant interpolation per iteration,…

Optimization and Control · Mathematics 2025-04-11 Mokhwa Lee , Yifan Sun

Quenched chiral perturbation is used to study the decay constants for heavy-light mesons beyond the leading order in 1/M. The results are used to estimate the error in quenched lattice calculations of the decay constants. For the double…

High Energy Physics - Phenomenology · Physics 2008-02-03 Michael J. Booth

QCD equations for generating functionals are solved at coinciding momenta of particles. As a result, the relations for $q$-particle correlation functions at equal momenta are obtained. They are directly connected to previously derived…

High Energy Physics - Phenomenology · Physics 2016-09-01 I. M. DREMIN

We calculate the probability (``quenching weight'') that a hard parton radiates an additional energy fraction due to scattering in spatially extended QCD matter. This study is based on an exact treatment of finite in-medium path length, it…

High Energy Physics - Phenomenology · Physics 2009-11-10 Carlos A. Salgado , Urs Achim Wiedemann

We develop chiral perturbation theory for baryons in quenched QCD. Quenching (the elimination of diagrams containing virtual quark loops) is achieved by extending the Lagrangian method of Bernard and Golterman, and is implemented in a…

High Energy Physics - Lattice · Physics 2009-10-28 James N. Labrenz , Stephen R. Sharpe

We give a new description to obtain the shear viscosity in QCD at finite temperature. Firstly, we obtain the correlation function of the renormalized energy-momentum tensor using the gradient flow method. Secondly, we estimate the spectral…

High Energy Physics - Lattice · Physics 2021-11-02 Etsuko Itou , Yuki Nagai

We review the results of large scale simulations of noncompact quenched $QED$ which use spectrum and Equation of State calculations to determine the theory's phase diagram, critical indices, and continuum limit. The resulting anomalous…

High Energy Physics - Lattice · Physics 2009-10-22 Mp Lombardo , J. B. Kogut , A. Kocic , K. C. Wang

We present the inconsistencies which arise in quenched QCD in $\Delta I=1/2$ non-leptonic kaon decays using chiral perturbation theory (ChPT) to one loop. In particular we discuss how the lack of unitarity of the quenched theory invalidates…

High Energy Physics - Lattice · Physics 2016-09-01 C. J. D. Lin , G. Martinelli , E. Pallante , C. T. Sachrajda , G. Villadoro

We construct the quasi-parton distributions of mesons for two-dimensional QCD with either scalar or spinor quarks using the $1/N_c$ expansion. We show that in the infinite momentum limit, the parton distribution function is recovered in…

High Energy Physics - Phenomenology · Physics 2019-03-27 Xiangdong Ji , Yizhuang Liu , Ismail Zahed

We compute the masses of the $\pi$ and of the $\rho$ mesons in the quenched approximation on a lattice with fixed lattice spacing $a \simeq 0.145 \ \mathrm{fm}$ for SU($N$) gauge theory with $N = 2,3,4,6$. We find that a simple linear…

High Energy Physics - Theory · Physics 2009-12-10 Luigi Del Debbio , Biagio Lucini , Agostino Patella , Claudio Pica

We present spectral functions extracted from Euclidean-time correlation functions by using sparse modeling. Sparse modeling is a method that solves inverse problems by considering only the sparseness of the solution we seek. To check…

High Energy Physics - Lattice · Physics 2024-11-01 Junichi Takahashi , Hiroshi Ohno , Akio Tomiya

The chiral limit of finite-volume QCD is the $\epsilon$-regime of the theory. We discuss how this regime can be used for determining low-energy observables of QCD by means of comparisons between lattice simulations and quenched and…

High Energy Physics - Lattice · Physics 2016-09-01 P. H. Damgaard

The parameters in the pseudoscalar meson mass formula in quenched chiral perturbation theory to one-loop order are determined by quenched lattice QCD with overlap Dirac operator, and from which the light quark masses are determined with the…

High Energy Physics - Lattice · Physics 2008-11-26 Ting-Wai Chiu , Tung-Han Hsieh

The quenched approximation for QCD is, at present and in the foreseeable future, unavoidable in lattice calculations with realistic choices of the lattice spacing, volume and quark masses. In these lectures, I review the analytic study of…

High Energy Physics - Lattice · Physics 2014-11-17 Maarten F. L. Golterman

We construct a systematic expansion for full QCD. The leading term gives the valence (quenched) approximation.

High Energy Physics - Lattice · Physics 2008-02-03 J. Sexton , D. Weingarten

[This version is a minor revision of a previously submitted preprint. Only references have been changed.] We describe a technique for constructing the effective chiral theory for quenched QCD. The effective theory which results is a…

High Energy Physics - Lattice · Physics 2009-10-22 Claude Bernard , Maarten Golterman

We present results for physical quantities computed in quenched chiral perturbation theory and compare them with the corresponding unquenched expressions. We also point out an apparent theoretical problem of the quenched approximation.…

High Energy Physics - Lattice · Physics 2009-10-22 Claude Bernard , Maarten Golterman

We present results of a quenched QCD simulation with overlap fermions on a lattice of volume V = 16^3X32 at beta=6.0, which corresponds approximatively to a lattice cutoff of 2 GeV and an extension of 1.4 fm. From the two-point correlation…

High Energy Physics - Lattice · Physics 2015-06-25 L. Giusti , C. Hoelbling , C. Rebbi