摘要:

We discuss in what way flavour symmetry breaking through nondegenerate light quark masses and through the mixing of &pgr;0, &eegr;, &eegr;’modifies the Goldberger‐Treiman relations for the triplet, octet and in particular, for the generalizations to the flavour singlet channel. We derive simple new algebraic expressions for the &pgr;0–&eegr; and &pgr;0–&eegr;’mixing and show that the seemingly large isospin and flavour breaking which result from nondegenerate quark masses are to lowest order cancelled by the &pgr;0–&eegr;–&eegr;’mixing.

ISSN:0094-243X    

DOI:10.1063/1.40492

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We show that the size of the hard gluonic contribution to the first moment of the proton’s spin‐dependent structure functiong1is entirely a matter of the convention used in defining the quark distributions. If the UV regulator for the spin‐dependent quark distributions respects the gauge invariance of Green’s functions (allows shifts of loop momenta) and respects the analyticity structure of the unregulated distributions, then the hard gluonic contribution to the first moment ofg1vanishes. This is the case, for example, in dimensional regularization. By relaxing the requirement that the regulator allow shifts of loop momenta, we are able to obtain a nonvanishing hard gluonic contribution to the first moment ofg1. However, the first moments of the resulting quark distributions correspond to matrix elements that are either gauge variant or involve nonlocal operators and, hence, have no analogue in the standard operator‐product expansion.

ISSN:0094-243X    

DOI:10.1063/1.40493

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Based on general arguments and the explicit bag‐model calculation, we show that the twist‐3 contribution to the nucleon’s transverse spin‐dependent structure functiong2(x) is significant and its measurement allows us a clean study of high‐twist effects.

ISSN:0094-243X    

DOI:10.1063/1.40494

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Asymptotic S‐matrix techniques are applied to the identification of a Standard Model background to polarized deep‐inelastic scattering experiments at HERA in search of Right‐handed Charged Currents. It is also pointed out that the Asymptotic S‐matrix produces finite observables free of Mass‐Shell Anomalies.

ISSN:0094-243X    

DOI:10.1063/1.40495

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

HERMES is an experiment under preparation by an international collaboration of physicists from the United States, Germany, Canada, Italy and the Soviet Union to measure the deep inelastic spin‐dependent structure functions of the nucleon at DESY, Hamburg, Germany. The structure functions of the proton and neutron will be determined by a completely new technique using polarized internal gas targets of hydrogen, deuterium, and3He and the longitudinally polarized 35 GeV electron beam of the HERA electron storage ring. Measurement of the deep inelastic spin‐structure of both isospin states of the nucleon at the same kinematics and using the same apparatus will provide a high precision test of the Bjorken sum rule.

ISSN:0094-243X    

DOI:10.1063/1.40496

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We are planning to measure the spin‐dependent structure function of the neutron,gn1, in the kinematic range 0.04<x<0.6 forQ2≳1 (GeV/c)2. The experiment will use the 22.7 GeV polarized electron beam at SLAC scattering from a polarized3He gas target in End Station A. The scattered electrons will be detected by two fixed arm spectrometers. We expect to obtain our data in 1992.

ISSN:0094-243X    

DOI:10.1063/1.40498

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We point out various spin experiments that could be done if the polarized beam option is pursued at RHIC. The advantages of RHIC for investigating several current and future physics problems are discussed. In particular, the gluon spin dependent structure function of the nucleon could be measured cleanly and systematically. Relevant experience developed in conjunction with the Fermilab Polarized Beam program is also presented.

ISSN:0094-243X    

DOI:10.1063/1.40499

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The results of the study of possibilities to use spin‐orbital force in order to split a circulating beam to two polarized beams are presented in this report. It is shown that the original spin‐splitter idea which is based on using intrinsic spin‐orbital resonance is not sufficient for splitting, in principle, because the spin’s long lasting effect on particle betatron oscillations is reduced just to a small tune shift. The theorem on the conservation of the sum or difference of quantum orbital and spin numbers, i.e. the combined spin‐orbital invariance, is established for this case. The resonant RF magnetic field parallel to the plane of splitting is introduced in order to stabilize spin in the plane of its precession and remove the combined invariance. The new double‐resonance invariants are established, which describe the spin dynamics and the splitting process.

ISSN:0094-243X    

DOI:10.1063/1.40500

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Partity violation in elastic (polarized) electron‐ (unpolarized) deuteron scattering is considered in some detail, as a means to extract information on both vector and axial‐vector currents, and thus the strange quark content of the deuteron. Numerical estimates are made, using a simple model when required, to find the sensitivity to s‐quark components of the form factors.

ISSN:0094-243X    

DOI:10.1063/1.40501

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Several years ago a selfpolarization effect for stored (anti‐) protons and ions was investigated theoretically. The effect is based on the well‐known Stern‐Gerlach effect in gradient fields. The aim of the ongoing measurements at IUCF is to verify experimentally the various assumptions on which this effect is based. The final goal is to demonstrate this new polarization effect. The proposed effect could be a powerful tool to produce polarized stored hadron beams both in the low energy range and at SSC and LHC energies.

ISSN:0094-243X    

DOI:10.1063/1.40502

出版商:AIP    

年代:1991

数据来源: AIP