155 research outputs found
Perturbative and nonperturbative aspects of azimuthal asymmetries in polarized ep
We discuss the possibilities of testing of perturbative quantum
chromodynamics through azimuthal asymmetries in polarized ep in the context of
future collider and fixed target facilities, such as Electron Ion Collider and
TESLA-N.Comment: 4 pages, Latex. Talk presented at the 15th International Spin Physics
Symposium, Spin 2002, Brookhaven National Laboratory, September 9-14, 200
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.
Novel Transversity Properties in SIDIS
We consider a rescattering mechanism to calculate a leading twist -odd
pion fragmentation function, a candidate for filtering the transversity
properties of the nucleon. We evaluate the single spin azimuthal asymmetry for
a transversely polarized target in semi-inclusive deep inelastic scattering
(for HERMES kinematics) and the double -odd asymmetry in this
framework.Comment: To appear in the proceedings of 8th Conference on the Intersections
of Particle and Nuclear Physics (CIPANP 2003), New York, New York, 19-24 May
200
Novel Azimuthal Asymmetries in Drell Yan and Semi-inclusive Deep Inelastic Scattering
We consider the leading and sub-leading twist -odd and even contributions
to the azimuthal asymmetry in unpolarized dilepton production in
Drell-Yan Scattering. We estimate the contributions' effects at , , and energies in the framework of the
parton model using a quark diquark-spectator model of the nucleon to
approximate the soft contributions.Comment: 6 pages, 4 figure
Transversity Distribution and Polarized Fragmentation Function from Semi-inclusive Pion Electroproduction
A method is discussed to determine the hitherto unknown u-quark transversity
distribution from a planned HERMES measurement of a single-spin asymmetry in
semi-inclusive pion electroproduction off a transversely polarized target.
Assuming u-quark dominance, the measurement yields the shapes of the
transversity distribution and of the ratio of a polarized and the unpolarized
u-quark fragmentation functions. The unknown relative normalization can be
obtained by identifying the transversity distribution with the well-known
helicity distribution at large x. The systematic uncertainty of the method is
dominated by the assumption of u-quark dominance.Comment: 5 pages, 5 figures, revised version as will be published in EPJ
Mass Formula for a Stationary Axisymmetric Configuration and the Physical Realization of the Kerr Metric
We analyse the expression for the mass of a stationary axisymmetric
configuration in general relativity obtained in our previous work [1]. From the
generality of our formula and its incompatibility with the corresponding
expression in Kerr space-time we argue that a stationary equilibrium
distribution of a real matter cannot be a source of the Kerr metric.Comment: RevTex, 5 pages, no figure
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