Calculations of the infrared behavior of quantum chromodynamics: The color-singlet quark form factor in the near-mass-shell regime

1977 ◽  
Vol 16 (8) ◽  
pp. 2605-2611 ◽  
Author(s):  
Enrico C. Poggio
Keyword(s):  
Form Factor ◽  
Quantum Chromodynamics ◽  
Mass Shell ◽  
Color Singlet ◽  
Infrared Behavior

scholarly journals Strong CP violation in spin-1/2 singly charmed baryons

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Y. Ünal ◽  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Dipole Moment ◽  
Form Factor ◽  
Cp Violation ◽  
Mass Shell ◽  
Chiral Expansion ◽  
Renormalization Scheme ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Charmed Baryons

Abstract We report on the calculation of the CP-violating form factor F3 and the corresponding electric dipole moment for charmed baryons in the spin-1/2 sector generated by the QCD θ-term. We work in the framework of covariant baryon chiral perturbation theory within the extended-on-mass-shell renormalization scheme up to next-to-leading order in the chiral expansion.

Charmonia production in W → (cc̄)Ds(∗) decays

2021 ◽  
Vol 36 (09) ◽  
pp. 2150058
Author(s):  
A. V. Luchinsky ◽  
A. K. Likhoded
Keyword(s):  
Quantum Chromodynamics ◽  
Light Cone ◽  
Relativistic Quantum ◽  
Branching Fractions ◽  
Color Singlet ◽  
Leading Order ◽  
Paper Production ◽  
Quantum Numbers ◽  
Numerical Predictions ◽  
State Formula

In this paper, production of charmonium state [Formula: see text] in exclusive [Formula: see text] decays is analyzed in the framework of both leading order Non-relativistic Quantum Chromodynamics (NRQCD) and light-cone (LC) expansion models. Analytical and numerical predictions for the branching fractions of these decays in both the approaches are given. The typical value of the branching fractions is [Formula: see text][Formula: see text][Formula: see text] and it turns out that the LC results are significantly larger than NRQCD ones (approximately two or four times increase depending on the quantum numbers of the final particles), so the effect of internal quark motion should be taken into account. Some rough estimates of color-octet contributions are presented and it is shown that these contributions could be comparable with color-singlet results.

scholarly journals THE ELECTROMAGNETIC FORM FACTOR OF THE PION: RESULTS FROM THE LATTICE

2013 ◽  
Vol 22 (12) ◽  
pp. 1330030 ◽  
Author(s):  
BASTIAN B. BRANDT
Keyword(s):  
Form Factor ◽  
Quantum Chromodynamics ◽  
Quality Criteria ◽  
Vector Form ◽  
Physical Point ◽  
Lattice Quantum Chromodynamics ◽  
Lattice Quantum ◽  
Future Challenges ◽  
Recent Developments ◽  
Systematic Effects

This review contains an overview over recent results for the electromagnetic iso-vector form factor of the pion obtained in lattice quantum chromodynamics (QCD) with dynamical fermions. Particular attention is given to the extrapolation to the physical point and an easy assessment of the control over the main systematic effects by imposing quality criteria and an associated sign code, similar to the ones used by the FLAG working group. Also included is a brief discussion of recent developments and future challenges concerning the accurate extraction of the form factor in the lattice framework.

The pion form factor from twisted-mass lattice quantum chromodynamics

2006 ◽  
Vol 84 (6-7) ◽  
pp. 661-668
Author(s):  
A M Abdel-Rehim ◽  
R Lewis
Keyword(s):  
Form Factor ◽  
Quantum Chromodynamics ◽  
Lattice Qcd ◽  
Pion Form Factor ◽  
Explicit Computation ◽  
Lattice Quantum Chromodynamics ◽  
Zero Modes ◽  
Twisted Mass ◽  
Lattice Quantum ◽  
Insight Into

The pion form factor offers insight into the transition from perturbative to nonperturbative quantum chromodynamics (QCD), and is of current experimental interest. Twisted-mass lattice QCD is a method for eliminating unphysical zero modes from Wilson lattice simulations; it also allows for removal of the leading lattice spacing artifacts through a momentum-averaging prescription. In our study of the pion form factor, we performed the first explicit computation with momentum averaging in twisted-mass lattice QCD, and the first use of the GMRES-DR algorithm for twisted fermion matrix inversion.PACS No.: 12.38.Gc

scholarly journals QCD IN THE INFRARED WITH EXACT ANGULAR INTEGRATIONS

1998 ◽  
Vol 13 (13) ◽  
pp. 1055-1062 ◽  
Author(s):  
D. ATKINSON ◽  
J. C. R. BLOCH
Keyword(s):  
Fixed Point ◽  
Quantum Chromodynamics ◽  
Gluon Propagator ◽  
Simple Pole ◽  
Exact Calculation ◽  
Ghost Propagator ◽  
Infrared Behavior ◽  
Infrared Limit

In a previous paper we have shown that in quantum chromodynamics the gluon propagator vanishes in the infrared limit, while the ghost propagator is more singular than a simple pole. These results were obtained after angular averaging, but here we go beyond this approximation and perform an exact calculation of the angular integrals. The powers of the infrared behavior of the propagators are changed substantially. We find the very intriguing result that the gluon propagator vanishes in the infrared exactly like p2, whilst the ghost propagator is exactly as singular as 1/p4. We also find that the value of the infrared fixed point of the QCD coupling is much decreased: it is now equal to 4π/3.

ON GAUGE-INVARIANT GREEN FUNCTIONS

1986 ◽  
Vol 01 (07) ◽  
pp. 455-458
Author(s):  
R. DELBOURGO ◽  
G. THOMPSON
Keyword(s):  
Quantum Chromodynamics ◽  
Mass Shell ◽  
General Procedure ◽  
Green Functions ◽  
Gauge Invariant

A general procedure for defining gauge-invariant fields is presented. In this way it is possible to associate gauge-variant Green functions, in some particular gauge, with gauge-invariant quantities. This construction can be done regardless of whether a mass shell exists or not and should be useful for the colored sector in quantum chromodynamics.

Infrared Behavior in a Model for Quantum Electrodynamics

1973 ◽  
Vol 51 (24) ◽  
pp. 2511-2515
Author(s):  
Edward B. Manoukian
Keyword(s):  
Quantum Electrodynamics ◽  
Mass Shell ◽  
High Energy ◽  
Electron Propagator ◽  
Infrared Behavior ◽  
High Energy Behavior ◽  
Energy Behavior ◽  
Particular Solution ◽  
Set Up ◽  
Electron And Photon

In another paper, a particular solution of the Ward–Takahashi identity was set up as a model for quantum electrodynamics. The high energy behavior of the electron and photon propagators was investigated. The purpose of the present work is to investigate the asymptotic infrared behavior of the electron propagator near the mass shell in our model–theory. It is shown that, in general, it has a branch point, rather than just a pole at p2 = −m2, with the "singularity" being different from the known result of Abrikosov and Solov'ev, and coincides with theirs only in the gauge G = −1. The electron propagator, however, has rigorously a pole in the Yennie gauge.

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