101 research outputs found
QCD and Transverse-Spin Physics
A pedagogical presentation of single-spin asymmetries and transversity is
offered. Detailed discussion is given of various aspects of single-spin
asymmetries in lepton-nucleon and in hadron-hadron scattering and of the role
of perturbative QCD and evolution in the context of transversity.Comment: Talk at the International Workshop on QCD: QCD@Work 2003 - Conversano
(Italy) 14-18 June 2003 (eConf C030614). LaTeX2e; 8 pages; uses standard
LaTeX macros (including psfrag), conference class file wqcd03.cls, and some
personal macros (included). Figures are eps and feynmp generated (included in
subfolders
Transversity and Drell-Yan -Factors
The Drell-Yan -factors for transversely polarised hadrons are examined.
Since transverse spin is peculiar in having no DIS reference point, the effects
of higher-order corrections on DY asymmetries are examined via a DIS definition
for transversity devised using a hypothetical scalar vertex. The results
suggest that some care may be required when interpreting experimentally
extracted partonic transversity, particularly when comparing with model
calculations or predictions.Comment: 4 pages, 2 figures (eps and feynmp); uses World Scientific class
ws-procs9x6, standard LaTeX/MiKTeX packages [amsmath, feynmp, graphicx,
natbib, psfrag] and one homespun package (included in the zip file);
contributed talk to appear in proc. of the XVI Int. Symp. on High-Energy Spin
Physics, Trieste (Oct. 2004
Hyperon Beta-Decay Analysis and the Recent KTeV Data
The analysis of hyperon semi-leptonic decay data is addressed with reference
to SU(3) breaking and isospin mixing between Lambda^O and Sigma^O. Various
approaches to SU(3) breaking are discussed and compared. The phenomenological
implications of Lambda^0-Sigma^0 mixing are not to be underestimated: it can
induce vector couplings in decays otherwise purely axial and may also modify
rates. In regard of the KTeV data on Xi^0O -> Sigma^+ e antineutrino,
predictions are presented and the impact of present a future data on the
extraction of F and D is also examined. In addition, the implications of the
new data for the use of octet baryon beta decays in determining V_us are
considered.Comment: 5 pages, uses aipproc.cls, aipproc.sty (included), axodraw.sty,
cite.sty. Presented at SPIN 2000 (Osaka, Oct. 2000
Semi-Inclusive DIS and Transversity
A review is presented of some aspects of semi-inclusive deeply inelastic
scattering and transversity. In particular, the role of -dependent and
higher-twist (or multi-parton) distributions in generating single-spin
asymmetries is discussed.Comment: 8 pages, uses aipproc.cls, feynmp, psfrag, and some personal packages
(included); invited talk presented at HiX 2004, Marseille, 26-28 July 200
Single-Spin Asymmetries and Transversity
A pedagogical introduction to single-spin asymmetries (SSA's) and
transversity is presented. Discussion in some detail is made of certain aspects
of (SSA's) in lepton-nucleon and in hadron-hadron scattering and the role of
pQCD and evolution in the context of transversity.Comment: 10 pages, 11 figures, presented at the XV International Symposium on
High-Energy Spin Physics (Brookhaven, 9-14 Aug. 2002
A New Quark Model Approach to Hyperon Semi-Leptonic Decays
A new analysis of hyperon semi-leptonic decay data is presented, based on
simple and general arguments for an SU(3)-breaking structure of the couplings
involved. The results obtained are compatible with those of earlier
investigations and highlight the uncertainties inherent in extraction of the
V_us Cabibbo-Kobayashi-Maskawa matrix element from such data, and the need for
complete analyses. For F and D, the results can be summarised by the ratio:
F/D=0.57+/-0.01; while as far as the value of V_us is concerned, the only
conclusion to be drawn is that, insofar as SU(3) breaking is still not totally
under control, the value obtained is compatible but not competitive with that
obtained from kaon semi-leptonic decays.Comment: 10 pages, Latex, uses FEYNMAN macros Presented at the Topical
Workshop on Deep Inelastic Scattering off Polarized Targets: Theory Meets
Experiment---Zeuthen, Sept. 199
Hyperon Beta Decay and the CKM Matrix
I shall present a pedagogical discussion of hyperon semileptonic decays,
covering some of the historical background, the basics notions of hyperon
semileptonic decays, deeply inelastic scattering and the CKM matrix, and the
description of SU(2) and SU(3) breaking. I shall also present a prediction for
a process under current experimental study.Comment: 10 Pages, LaTeX2e, 1 EPS figure + 2 FeynFM figures. Invited talk at
the Advanced Studies Institute, Symmetries and SPIN (SPIN-Praha-2003),
Prague, July 12-19, 2003. Uses cjpsuppl.cls class file and other included
style file
Proton Spin, Sum Rules, QCD and Higher Twist
We examine the present status of the Bjorken sum rule in the light of recent
data on the spin structure functions of the proton, neutron and deuteron
obtained by the CERN and SLAC experimental groups. We also discuss the role of
possible higher-twist contributions and higher-order PQCD corrections and
comment on the extraction of the necessary parameters, D and F, obtained from
hyperon semi-leptonic decays.Comment: 4 pages, latex, no figures, requires the QCDPARIS.STY style file. One
minor correction to references mad
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