1,185 research outputs found
Lambda and Lambda-bar Polarization in Lepton Induced Processes
The study of the longitudinal polarization of Lambda and Lambda-bar hyperons
produced in polarized deep inelastic scattering, neutrino scattering, and in Z0
decays allows to access the spin dynamics of the quark fragmentation process.
Different phenomenological spin transfer mechanisms are considered and
predictions for the Lambda and Lambda-bar longitudinal polarization in various
processes using unpolarized and polarized targets are made. Current and future
semi-inclusive deep inelastic scattering experiments will provide soon accurate
enough data to study these phenomena and distinguish between various models for
the spin transfer mechanisms.Comment: 17 pages, LaTex with epsfig.sty, including 10 figures One reference
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Gluon Polarization from Correlated High-p_T Hadron Pairs in Polarized l - N Scattering
We propose to access the gluon polarization by measuring the cross
section spin-asymmetry in semi-inclusive polarized lepton -- nucleon
scattering. The photon-gluon fusion sub-process will be tagged by detecting
high- correlated hadron pairs in the forward hemisphere. Selecting
oppositely charged kaon pairs will allow to suppress the background coming from
gluon radiation.Comment: 6 pages, 3 eps figures, aipproc.cls and aipproc.sty include
Gluon polarization from correlated high-pT hadron pairs in polarized electro-production
We propose to measure the gluon distribution function Delta G(eta) at eta <
0.2 via pseudo jet production in polarized fixed target lepton nucleon
scattering at typical lepton beam energies of 200 GeV. The measurement of the
spin-asymmetry for the production of correlated charge conjugated hadrons of
opposite transverse momentum can be directly related to Delta G(eta) through
the photo-gluon fusion process. Wa also present a numerical analysis of the
accuracy which can be obtained for different flavors and kinematics of the
observed hadron pair.Comment: 18 pages, 6 eps figure
On the azimuthal asymmetries in DIS
Using the recent experimental data on the left right asymmetry in
fragmentation of transversely polarized quarks and the theoretical calculation
of the proton transversity distribution in the effective chiral quark soliton
model we explain the azimuthal asymmetries in semi-inclusive hadron production
on longitudinal (HERMES) and transversely (SMC) polarized targets with no free
parameters. On this basis we state that the proton transversity distribution
could be successfully measured in future DIS experiments with longitudinally
polarized target.Comment: 8 pages, latex, 5 eps figures, uses epsfig and wrapfi
Production mechanisms and single-spin asymmetry for kaons in high energy hadron-hadron collisions
Direct consequences on kaon production of the picture proposed in a recent
Letter and subsequent publications are discussed. Further evidence supporting
the proposed picture is obtained. Comparison with the data for the inclusive
cross sections in unpolarized reactions is made. Quantitative results for the
left-right asymmetry in single-spin processes are presented.Comment: 10 pages, 2 Postscript figure
Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron collisions
We discuss Lambda polarization and single-spin left-right asymmetry in
diffractive hadron-hadron scattering at high energies. We show that the
physical picture proposed in a recent Letter is consistent with the
experimental observation that polarization in the diffractive
process, , is much higher than that in the inclusive
reaction, . We make predictions for the left-right asymmetry,
A_N, and for the spin transfer, , in the single-spin process
and suggest further experimental tests of the
proposed picture.Comment: 14 pages, 3 ps-figures. Phys. Rev. D (in press
Perturbative contribution to the sin(phi) asymmetry in inclusive pi^{+} electroproduction
We consider the sin(phi) single target-spin asymmetry in deep-inelastic
pi^{+} inclusive electroproduction off a longitudinally polarized target. We
show that at larger transverse momentum of the outgoing hadron the evaluated
asymmetry decreases if one takes into account the first order alpha_S
perturbative contribution to the cross section, integrated over the azimuthal
angle. This leads to good agreement with recent HERMES data.Comment: 4 pages with one figure, LaTeX, typos corrected. Contribution to the
Proceedings of the QCD'00 Euroconference, Montpellier, 6-13th July 2000, to
appear in the Nucl. Phys. B (Proc. Suppl.
How Could the Proton Transversity be Measured
The perspectives of two new nonstandard methods of transversal quark
polarization measurement are considered: the jet handedness and the so-called
"Collins effect" due to spin dependent T-odd fragmentation function responsible
for the left-right asymmetry in fragmenting of transversally polarized quarks.
Recent experimental indications in favor of these effects are observed: 1.The
correlation of the T-odd one-particle fragmentation functions found by DELPHI
in -jet decay. Integrated over the fraction of longitudinal and
transversal momenta, this correlation is of 1.6% order, which means order of
13% for the analyzing power. 2.A rather large () handedness
transversal to the production plane observed in the diffractive production of
() triples from nuclei by the --beam.
It shows a clear dynamic origin and resembles the single spin asymmetry
behavior.
All this makes us hope to use these effects in polarized DIS experiments for
transversity measurement. The first estimation of transversity was done by
using the azimuthal asymmetry in semi-inclusive DIS recently measured by HERMES
and SMC.Comment: 8 pages, Latex, czjphys2.sty. Talk at Int. Workshop "PRAHA-SPIN99",
Prague 6-11 Sept 1999. To appear in Czech.J.Phys Supp
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