3,106 research outputs found
Single transverse spin asymmetries in inclusive hadron production
A consistent phenomenological approach to the computation of transverse
single spin asymmetries in inclusive hadron production is presented, based on
the assumed generalization of the QCD factorization theorem to the case in
which quark intrinsic motion is taken into account. New k_T and spin dependent
quark distribution and fragmentation functions are considered: some of them are
fixed by fitting data on p(transv. polarized) + p -> pion + X and predictions
are given for single spin asymmetries in l + p(transv. polarized) -> pion + X
and gamma^* + p(transv. polarized) -> pion + X processes.Comment: LaTeX, 3 pages, 2 eps figures, uses epsfig.sty, fleqn.sty, npb.sty.
Talk delivered by M. Anselmino at the 7th International Workshop on Deep
Inelastic Scattering and QCD (DIS99), Zeuthen, April 1999, to appear in Nucl.
Phys. B (Proc. Suppl.
Weak interactions in polarized semi-inclusive DIS
We calculate, within pQCD parton model at leading orders, the expression of
the polarization P of spin 1/2 hadrons (typically Lambda baryons), produced in
polarized semi-inclusive DIS in all possible cases in which weak interactions
are involved. We discuss how to gather new information on fragmentation and
distribution functions and give numerical estimates in the cases for which data
are or will soon be available.Comment: LaTeX, 33+1 pages, 12 ps figures, uses epsfig.st
Longitudinal Lambda polarization in polarized semi-inclusive DIS
We calculate, within pQCD parton model at leading orders, the expression of
the longitudinal polarization of Lambda baryons produced in polarized
semi-inclusive DIS, including weak interaction effects. We present some
numerical estimates in few cases for which data are or will soon be available
and discuss how to gather new information on polarized fragmentation functions.Comment: LaTeX, 4 pages, 2 ps figures, uses sprocl.sty and epsfig.sty; Talk
delivered by U. D'Alesio at the IX International Workshop on Deep Inelastic
Scattering (DIS2001), Bologna, 27 April - 1 May, 200
Spin Measurements in lp -> hX Deep Inelastic Scattering
The production of hadrons in polarized lepton-nucleon deep inelastic
scattering is discussed. The helicity density matrix of the hadron is computed
within the QCD hard scattering formalism and its elements are shown to yield
information on the spin structure of the nucleon and the spin dependence of the
quark fragmentation process. The case of vector mesons is considered in
more detail and estimates are given.Comment: 3 pages, LaTeX, no figures. Talk delivered by J. Hansson at the XII
International Symposium on High Energy Spin Physics, Amsterdam, Sept. 10-14,
1996. To be published in the proceeding
Cosmic rays in magnetized intracluster plasma
Recent results are reported on Magnetic Fields in Clusters of Galaxies,
Diffuse Radio Emission, and Radio - X-ray connection in Radio Halos.Comment: 2 pages, 1 figure, Invited talk at the JD15 "Magnetic Fields in
Diffuse Media", IAU XXVII General Assembly, Rio de Janeir
Spin effects in the fragmentation of a transversely polarized quark
An azimuthal dependence of pions produced in polarized Deep Inelastic
Scattering, gamma^* - p(transv. polarized) -> pion + X, has been recently
observed and might be related to the so-called Collins effect. We discuss in
details, for a general spin configuration of the nucleon, the kinematics of the
process and methods of extracting information on the fragmentation properties
of a polarized quark. Assuming that the observed azimuthal dependence is indeed
due to Collins effect, we derive a lower bound estimate for the size of the
quark analysing power, which turns out to be large.Comment: 18+1 pages, LaTeX, 5 eps figures, uses epsfig.sty; v2: Some technical
problems in dimensions of Figs. 2 and 3 remove
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