scholarly journals The Drell–Hearn–Gerasimov Sum-Rule in QCD

1997 ◽  
Vol 12 (15) ◽  
pp. 1051-1067 ◽  
Author(s):  
S. D. Bass
Keyword(s):  
Standard Model ◽  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Magnetic Moment ◽  
Present Status ◽  
Spin Structure ◽  
Sum Rules ◽  
Sum Rule ◽  
Minimal Standard ◽  
Polarized Deep Inelastic Scattering

Photoproduction spin sum-rules offer a new window on the spin structure of the nucleon that complements the information we can learn from polarized deep inelastic scattering experiments. We review the theory and present status of the Drell–Hearn–Gerasimov sum-rule in QCD, emphasizing the possible relation between the present "discrepancy" in this sum-rule and the nucleon's strangeness magnetic moment. In the case of an elementary electron or photon target (say at the NLC) the Drell–Hearn–Gerasimov sum-rule provides a test for physics beyond the minimal Standard Model.

SPIN STRUCTURE OF THE NUCLEON STUDIED BY HERMES

2003 ◽  
Vol 18 (08) ◽  
pp. 1161-1168
Author(s):  
◽  
TOSHI-AKI SHIBATA
Keyword(s):  
Electron Beam ◽  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Spin Structure ◽  
Magnetic Spectrometer ◽  
Particle Identification ◽  
Wide Acceptance ◽  
Basic Concepts ◽  
Gas Targets ◽  
Polarized Deep Inelastic Scattering

The spin structure of the proton and neutron is studied by polarized deep inelastic scattering at HERMES. The longitudinally polarized electron beam at 27.6 GeV, polarized internal gas targets of 3 He , H and D, and a wide acceptance magnetic spectrometer with a particle identification capability are the important ingredients of the experiment. The basic concepts of the measurements at HERMES as well as recent physics results are presented.

PARTON DISTRIBUTIONS IN THE NUCLEON AND THE PAULI PRINCIPLE

1993 ◽  
Vol 08 (03) ◽  
pp. 225-231 ◽  
Author(s):  
FRANCO BUCCELLA ◽  
JACQUES SOFFER
Keyword(s):  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Sum Rules ◽  
Pauli Principle ◽  
Scattering Data ◽  
Parton Distributions ◽  
Sum Rule ◽  
Bjorken Sum Rule ◽  
Deep Inelastic Scattering Data

The Pauli principle is used, together with some deep inelastic scattering data, to guide us in making reasonable assumptions for various polarized parton distributions in terms of unpolarized distributions. We relate the violation of the Gottfried and Ellis-Jaffe sum rules and we anticipate a substantial violation of the Bjorken sum rule.

scholarly journals ESTIMATES OF THE HIGHER ORDER QCD CORRECTIONS TO R(s), Rτ AND DEEP INELASTIC SCATTERING SUM RULES

1995 ◽  
Vol 10 (03) ◽  
pp. 235-250 ◽  
Author(s):  
ANDREI L. KATAEV ◽  
VALERY V. STARSHENKO
Keyword(s):  
Inelastic Scattering ◽  
Deep Inelastic Scattering ◽  
Sum Rules ◽  
Higher Order ◽  
Analytical Continuation ◽  
Sum Rule ◽  
Euclidean Region ◽  
Effective Charges ◽  
Physical Quantities ◽  
Perturbative Corrections

We present the attempt to study the problem of the estimates of higher order perturbative corrections to physical quantities in the Euclidean region. Our considerations are based on the application of the scheme-invariant methods, namely the principle of minimal sensitivity and the effective charges approach. We emphasize that in order to obtain the concrete results for the physical quantities in the Minkowskian region the results of application of this formalism should be supplemented by the explicit calculations of the effects of the analytical continuation. We present the estimates of the order [Formula: see text] QCD corrections to the Euclidean quantities: the e+e−-annihilation D-function and the deep inelastic scattering sum rules, namely the nonpolarized and polarized Bjorken sum rules and to the Gross–Llewellyn Smith sum rule. The results for the D-function are further applied to estimate the [Formula: see text] QCD corrections to the Minkowskian quantities R(s) = σ tot (e+e− → hadrons )/σ(e+e− → µ+µ−) and [Formula: see text]. The problem of the fixation of the uncertainties due to the [Formula: see text] corrections to the considered quantities is also discussed.

scholarly journals Polarized Deep Inelastic Scattering

1997 ◽  
Vol 50 (1) ◽  
pp. 71
Author(s):  
F. M. Steffens ◽  
A. W. Thomas
Keyword(s):  
Inelastic Scattering ◽  
Structure Function ◽  
Spin Structure ◽  
Good Description ◽  
Proton Spin ◽  
Spin Structure Function ◽  
Sum Rule ◽  
Axial Anomaly ◽  
Proton Spin Structure ◽  
Polarized Deep Inelastic Scattering

We give an overview of present calculations involving the proton spin structure function. It is shown that a significant part of the discepancy between the data and the Ellis–Jaffe sum-rule may arise through the axial anomaly if the gluons within the proton are strongly polarized. While a quark model, such as the MIT bag, does not include the anomaly, and therefore cannot be expected to reproduce the spin structure function, it does give a rather good description of recent data which is anomaly free, such as the distribution of polarized, valence up-quarks in the proton.

POLARIZED DEEP INELASTIC SCATTERING FROM PHOTON TARGETS AND AXIAL ANOMALIES

1992 ◽  
Vol 07 (24) ◽  
pp. 6039-6051 ◽  
Author(s):  
STEVEN D. BASS
Keyword(s):  
Inelastic Scattering ◽  
Structure Function ◽  
Deep Inelastic Scattering ◽  
Gauge Invariance ◽  
Photon Structure ◽  
Sum Rule ◽  
Definition Of ◽  
First Moment ◽  
Polarized Deep Inelastic Scattering

We discuss the polarized photon structure function [Formula: see text] and focus on the first moment of [Formula: see text], where we explore the role of the axial QED and strong U(1) anomalies. Electromagnetic gauge invariance determines an exact sum rule for the first moment of [Formula: see text]. If we accept a recently proposed definition of “spin content” then we must also accept a polarized gluon component of Δgγ=2π/αs in the spin-one photon.

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