scholarly journals PROTON STRUCTURE FUNCTIONS FROM CHIRAL DYNAMICS AND QCD CONSTRAINTS

1998 ◽  
Vol 13 (01) ◽  
pp. 71-82 ◽  
Author(s):  
H. J. WEBER
Keyword(s):  
Field Theory ◽  
Detailed Comparison ◽  
Structure Functions ◽  
Chiral Field ◽  
Quark Masses ◽  
Goldstone Bosons ◽  
Proton Structure ◽  
Regge Behavior ◽  
Small X ◽  
Bjorken X

The spin fractions and deep inelastic lepton structure functions of the proton are analyzed based on chiral field theory invloving Goldstone bosons. A detailed comparison with several recent chiral models sheds light on their successful description of the spin fractions of the proton as being due to neglecting quark masses. Initial quark valence distributions at a higher scale than Λ QCD are constructed using quark counting constraints at large Bjorken x→1 and Regge behavior at small x. Reasonable strange quark distributions are then predicted by chiral field theory. The spin fractions also agree with the data.

scholarly journals PROTON STRUCTURE FUNCTIONS FROM CHIRAL DYNAMICS AND QCD CONSTRAINTS

1999 ◽  
Vol 14 (19) ◽  
pp. 3005-3027 ◽  
Author(s):  
H. J. WEBER
Keyword(s):  
Field Theory ◽  
Goldstone Boson ◽  
Detailed Comparison ◽  
Structure Functions ◽  
Proton Spin ◽  
Chiral Field ◽  
Pure Spin ◽  
Regge Behavior ◽  
Order Of Magnitude ◽  
Bjorken X

The spin fractions and deep inelastic lepton structure functions of the proton are analyzed using chiral field theory involving Goldstone bosons. A detailed comparison with recent chiral models sheds light on their successful description of the spin fractions of the proton as being due to neglecting helicity nonflip chiral transitions. This approximation is valid for zero mass but not for constituent quarks. Since the chiral spin fraction models with the pure spin-flip approximation reproduce the measured spin fractions of the proton, axialvector constituent-quark-Goldstone boson couplings are found to be inconsistent with the proton spin data. Initial quark valence distributions are then constructed using quark counting constraints at Bjorken x→1 and Regge behavior at x→0. Sea quark distributions predicted by chiral field theory on this basis have the correct order of magnitude and shape. The spin fractions also agree with the data.

scholarly journals EVOLUTION OF STRUCTURE FUNCTIONS AND THEIR MOMENTS IN CHIRAL FIELD THEORY

2003 ◽  
Vol 18 (04) ◽  
pp. 593-606
Author(s):  
KAKALI RAY-MAITY ◽  
PADMANABHA DASGUPTA
Keyword(s):  
Field Theory ◽  
Evolution Equations ◽  
Probabilistic Approach ◽  
Perturbation Expansion ◽  
Structure Functions ◽  
Evolution Process ◽  
Effective Theory ◽  
Chiral Field ◽  
Coupling Constant ◽  
Evolution Of Structure

Evolution of structure functions and their moments at low and moderate Q2 is studied in the chiral field theory. Evolution equations based on perturbation expansion in the coupling constant of the effective theory are derived and solved for the moments. The kernels of evolution arising from different processes have been calculated with contributions from direct and cross channels, the interference terms being non-negligible in the kinematic regions under consideration. This is shown to lead to flavor-dependence of the kernels which manifests in observable effects. The invalidity of the probabilistic approach to the evolution process is also pointed out.

scholarly journals A phenomenological solution small x to the longitudinal structure function dynamical behavior

2014 ◽  
Vol 29 (32) ◽  
pp. 1450189 ◽  
Author(s):  
G. R. Boroun ◽  
B. Rezaei ◽  
J. K. Sarma
Keyword(s):  
Structure Function ◽  
Dynamical Behavior ◽  
Structure Functions ◽  
Proton Structure Function ◽  
Leading Order ◽  
Longitudinal Structure ◽  
Proton Structure ◽  
Longitudinal Structure Function ◽  
Color Dipole ◽  
Small X

In this paper, the evolutions of longitudinal proton structure function have been obtained at small x up to next-to-next-to-leading order using a hard Pomeron behavior. In our paper, evolutions of gluonic as well as heavy longitudinal structure functions have been obtained separately and the total contributions have been calculated. The total longitudinal structure functions have been compared with results of Donnachie–Landshoff (DL) model, Color Dipole (CD) model, kT factorization and H1 data.

scholarly journals ON THE SINGULAR BEHAVIOR OF STRUCTURE FUNCTIONS AT LOW x

1994 ◽  
Vol 09 (36) ◽  
pp. 3393-3402 ◽  
Author(s):  
H. NAVELET ◽  
R. PESCHANSKI ◽  
S. WALLON
Keyword(s):  
Structure Function ◽  
Evolution Equations ◽  
Structure Functions ◽  
Saddle Point Method ◽  
Proton Structure Function ◽  
Singular Behavior ◽  
Proton Structure ◽  
Small X ◽  
Model Independent ◽  
Low X

We discuss the phenomenological extraction of the leading j-plane singularity from singlet structure functions Fs estimated at small x. Using a saddle point method we show that [Formula: see text] is a suitable observable for this purpose in the region x≤10−2. As an application, we confront and distinguish in a model-independent way structure function parametrizations coming from two different QCD evolution equations, namely the Lipatov (or BFKL) equation and the Gribov-Lipatov-Altarelli-Parisi (or GLAP) equation. Recent results on the proton structure function F2 at HERA are discussed in this framework.

Light front field theory: An advanced Primer

2007 ◽  
Vol 57 (3) ◽  
Author(s):  
L'ubomír Martinovič
Keyword(s):  
Field Theory ◽  
Detailed Comparison ◽  
Light Front ◽  
Two Dimensional ◽  
Schwinger Model ◽  
Initial Space ◽  
Model Hamiltonian ◽  
Spatial Volume ◽  
Hamiltonian Perturbation Theory ◽  
Light Front Quantization

Light front field theory: An advanced PrimerWe present an elementary introduction to quantum field theory formulated in terms of Dirac's light front variables. In addition to general principles and methods, a few more specific topics and approaches based on the author's work will be discussed. Most of the discussion deals with massive two-dimensional models formulated in a finite spatial volume starting with a detailed comparison between quantization of massive free fields in the usual field theory and the light front (LF) quantization. We discuss basic properties such as relativistic invariance and causality. After the LF treatment of the soluble Federbush model, a LF approach to spontaneous symmetry breaking is explained and a simple gauge theory - the massive Schwinger model in various gauges is studied. A LF version of bosonization and the massive Thirring model are also discussed. A special chapter is devoted to the method of discretized light cone quantization and its application to calculations of the properties of quantum solitons. The problem of LF zero modes is illustrated with the example of the two-dimensional Yukawa model. Hamiltonian perturbation theory in the LF formulation is derived and applied to a few simple processes to demonstrate its advantages. As a byproduct, it is shown that the LF theory cannot be obtained as a "light-like" limit of the usual field theory quantized on an initial space-like surface. A simple LF formulation of the Higgs mechanism is then given. Since our intention was to provide a treatment of the light front quantization accessible to postgradual students, an effort was made to discuss most of the topics pedagogically and a number of technical details and derivations are contained in the appendices.

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