scholarly journals Quantum chromodynamics and the dynamics of hadrons. [Review, bound state, perturbation theory]

1979 ◽  
Author(s):  
S.J. Brodsky
Keyword(s):  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Bound State

scholarly journals The Leutwyler–Smilga relation on the lattice

2019 ◽  
Vol 35 (01) ◽  
pp. 1950346 ◽  
Author(s):  
Gernot Münster ◽  
Raimar Wulkenhaar
Keyword(s):  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Lattice Qcd ◽  
Chiral Perturbation Theory ◽  
Effective Action ◽  
Lattice Spacing ◽  
Chiral Perturbation ◽  
Quark Masses

According to the Leutwyler–Smilga relation, in Quantum Chromodynamics (QCD), the topological susceptibility vanishes linearly with the quark masses. Calculations of the topological susceptibility in the context of lattice QCD, extrapolated to zero quark masses, show a remnant nonzero value as a lattice artefact. Employing the Atiyah–Singer theorem in the framework of Symanzik’s effective action and chiral perturbation theory, we show the validity of the Leutwyler–Smilga relation in lattice QCD with lattice artefacts of order a2 in the lattice spacing a.

Operator expansion in quantum chromodynamics beyond perturbation theory

1980 ◽  
Vol 174 (2-3) ◽  
pp. 378-396 ◽  
Author(s):  
V.A. Novikov ◽  
M.A. Shifman ◽  
A.I. Vainshtein ◽  
V.I. Zakharov
Keyword(s):  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Operator Expansion

scholarly journals Hamiltonian approach to QCD in Coulomb gauge: Perturbative treatment of the quark sector

2015 ◽  
Vol 30 (17) ◽  
pp. 1550100 ◽  
Author(s):  
Davide R. Campagnari ◽  
Hugo Reinhardt
Keyword(s):  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Quark Propagator ◽  
Functional Integral ◽  
Coulomb Gauge ◽  
Hamiltonian Approach ◽  
Equal Time ◽  
Quark Sector ◽  
Schrödinger Perturbation ◽  
Perturbative Treatment

We study the static gluon and quark propagator of the Hamiltonian approach to quantum chromodynamics in Coulomb gauge in one-loop Rayleigh–Schrödinger perturbation theory. We show that the results agree with the equal-time limit of the four-dimensional propagators evaluated in the functional integral (Lagrangian) approach.

The principle of minimum sensitivity and moments of nonsinglet structure functions

1983 ◽  
Vol 61 (1) ◽  
pp. 99-101 ◽  
Author(s):  
Gerry McKeon
Keyword(s):  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Finite Order ◽  
Parton Model ◽  
Structure Functions ◽  
Renormalization Procedure ◽  
Dependent Part ◽  
Model Predictions ◽  
Minimum Sensitivity

The corrections implied by quantum chromodynamics to parton model predictions are not unique to finite order in perturbation theory on account of the possibility of choosing different renormalization schemes. Stevenson has provided a criterion for selecting the "best" renormalization procedure; the so-called "principle of minimum sensitivity" (PMS). This criterion is applied here to the Q2-dependent part of the moments of the nonsinglet structure functions in lepton–hadron scattering.

BINDING ENERGIES IN WEAKLY COUPLED (2+1)-DIMENSIONAL QUANTUM FIELD THEORIES

1991 ◽  
Vol 06 (29) ◽  
pp. 2705-2711
Author(s):  
G. GAT ◽  
B. ROSENSTEIN
Keyword(s):  
Perturbation Theory ◽  
Binding Energy ◽  
Bound State ◽  
Binding Energies ◽  
Field Theories ◽  
General Question ◽  
Quantum Field Theories ◽  
Quantum Field ◽  
Weakly Coupled ◽  
Gross Neveu Model

We calculate the binding energy of the two-particle threshold bound state in the (2+1)-dimensional Gross-Neveu model. This model was recently shown to be renormalizable within the 1/N expansion. The binding energy is found to be ΔE=4mc-8Nf where m is the mass of the elementary fermion and Nf is the number of flavors. The general question of consistency of the perturbation theory within the framework of the Bethe-Salpeter equation is discussed.

scholarly journals QCD beyond diagrams

2021 ◽  
Vol 36 (21) ◽  
pp. 2130012
Author(s):  
Michael Creutz
Keyword(s):  
Perturbation Theory ◽  
Symmetry Breaking ◽  
Quantum Chromodynamics ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Strong Interactions ◽  
Quark Confinement ◽  
Mass Generation ◽  
Diagrammatic Perturbation Theory

Quantum chromodynamics (QCD), the theory of the strong interactions, involves quarks interacting with non-Abelian gluon fields. This theory has many features that are difficult to impossible to see in conventional diagrammatic perturbation theory. This includes quark confinement, mass generation and chiral symmetry breaking. This paper is a colloquium level overview of the framework for understanding how these effects come about.

scholarly journals Aspects on Effective Theories and the QCD Transition

Symmetry ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 945
Author(s):  
Angel Gómez Nicola
Keyword(s):  
Phase Diagram ◽  
Perturbation Theory ◽  
Quantum Chromodynamics ◽  
Chiral Symmetry ◽  
Current Knowledge ◽  
Chiral Symmetry Restoration ◽  
Chiral Perturbation ◽  
Ward Identities ◽  
Hadron Gas ◽  
Effective Theories

We review recent advances in the understanding of the Quantum Chromodynamics (QCD) transition and its nature, paying special attention to the analysis of chiral symmetry restoration within different approaches based on effective theories. After presenting some of the main aspects of the current knowledge of the phase diagram from the theoretical, experimental and lattice sides, we discuss some recent problems where approaches relying on effective theories have been particularly useful. In particular, the combination of ideas such as Chiral Perturbation Theory, unitarity and Ward Identities allows us to describe successfully several observables of interest. This is particularly relevant for quantities expected to be dominated by the light meson components of the hadron gas such as the scalar and topological susceptibilities. In addition, ward identities and effective Lagrangians provide systematic results regarding chiral and U ( 1 ) A partner degeneration properties which are of great importance for the interplay between those two transitions and the nature of chiral symmetry restoration. Special attention is paid to the connection of this theoretical framework with lattice simulations.

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