scholarly journals Alternative approach to light-front perturbation theory

2007 ◽  
Vol 75 (2) ◽  
Author(s):  
Thomas Heinzl
Keyword(s):  
Perturbation Theory ◽  
Light Front ◽  
Alternative Approach

Light front Hamiltonian for boson form of QED (1 + 1) in Pauli–Villars regularization

2019 ◽  
Vol 34 (21) ◽  
pp. 1950113
Author(s):  
V. A. Franke ◽  
M. Yu. Malyshev ◽  
S. A. Paston ◽  
E. V. Prokhvatilov ◽  
M. I. Vyazovsky
Keyword(s):  
Perturbation Theory ◽  
Chiral Perturbation Theory ◽  
Chiral Condensate ◽  
Light Front ◽  
Coupling Constants ◽  
Hamiltonian Approach ◽  
Chiral Perturbation ◽  
Dimensional Models ◽  
Villars Regularization ◽  
Ultraviolet Regularization

Light front (LF) Hamiltonian for QED in [Formula: see text] dimensions is constructed using the boson form of this model with additional Pauli–Villars-type ultraviolet regularization. Perturbation theory, generated by this LF Hamiltonian, is proved to be equivalent to usual covariant chiral perturbation theory. The obtained LF Hamiltonian depends explicitly on chiral condensate parameters which enter in a form of some renormalization of coupling constants. The obtained results can be useful when one attempts to apply LF Hamiltonian approach for [Formula: see text]-dimensional models like QCD.

scholarly journals CHIRAL PERTURBATION THEORY WITH NUCLEONS

1992 ◽  
Vol 01 (03) ◽  
pp. 561-601 ◽  
Author(s):  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Chiral Symmetry ◽  
Chiral Perturbation Theory ◽  
Chiral Limit ◽  
Nuclear Forces ◽  
Chiral Perturbation ◽  
Chiral Structure ◽  
Quark Masses ◽  
Alternative Approach ◽  
Working Out

I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external momenta and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward–identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the method. Some processes which are discussed are threshold photopion production, low-energy Compton scattering off nucleons, πN scattering and the σ–term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.

Variational mass perturbation theory for light-front bound-state equations

1998 ◽  
Vol 57 (4) ◽  
pp. 2460-2474 ◽  
Author(s):  
Koji Harada ◽  
Thomas Heinzl ◽  
Christian Stern
Keyword(s):  
Perturbation Theory ◽  
Bound State ◽  
Light Front ◽  
State Equations

scholarly journals TWIST-THREE DISTRIBUTION f⊥(x, k⊥) IN LIGHT-FRONT HAMILTONIAN APPROACH

2011 ◽  
Vol 26 (35) ◽  
pp. 2653-2662 ◽  
Author(s):  
A. MUKHERJEE ◽  
R. KORRAPATI
Keyword(s):  
Perturbation Theory ◽  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
The State ◽  
Light Front ◽  
Hamiltonian Approach ◽  
Gluon Interaction

We calculate the twist-three distribution f⊥(x, k⊥) contributing to Cahn effect in unpolarized semi-inclusive deep inelastic scattering. We use light-front Hamiltonian technique and take the state to be a dressed quark at one-loop in perturbation theory. The "genuine twist-three" contribution comes from the quark–gluon interaction part in the operator and is explicitly calculated. f⊥(x, k⊥) is compared with f1(x, k⊥).

scholarly journals Gluon cascades and amplitudes in light-front perturbation theory

2013 ◽  
Vol 869 (1) ◽  
pp. 1-30 ◽  
Author(s):  
C.A. Cruz-Santiago ◽  
A.M. Staśto
Keyword(s):  
Perturbation Theory ◽  
Light Front

scholarly journals UTILITY OF GALILEAN SYMMETRY IN LIGHT-FRONT PERTURBATION THEORY: A NONTRIVIAL EXAMPLE IN QCD

1998 ◽  
Vol 13 (26) ◽  
pp. 4591-4604 ◽  
Author(s):  
A. HARINDRANATH ◽  
RAJEN KUNDU
Keyword(s):  
Field Theory ◽  
Perturbation Theory ◽  
Complex Structure ◽  
Light Front ◽  
Tree Level ◽  
Two Dimensional ◽  
Coupling Constant ◽  
Two Component ◽  
Covariant Field ◽  
Galilean Symmetry

Investigations have revealed a very complex structure for the coefficient functions accompanying the divergences for individual time(x+)-ordered diagrams in light-front perturbation theory. No guidelines seem to be available to look for possible mistakes in the structure of these coefficient functions emerging at the end of a long and tedious calculation, in contrast to covariant field theory. Since, in light-front field theory, the transverse boost generator is a kinematical operator which acts just like the two-dimensional Galilean boost generator in nonrelativistic dynamics, it may provide some constraint on the resulting structures. In this work we investigate the utility of Galilean symmetry beyond tree level in the context of coupling constant renormalization in light-front QCD using the two-component formalism. We show that for each x+-ordered diagram separately, the underlying transverse boost symmetry fixes relative signs of terms in the coefficient functions accompanying the diverging logarithms. We also summarize the results leading to coupling constant renormalization for the most general kinematics.

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