2,048 research outputs found
Recent results on cold-QCD from RHIC
Polarized proton-proton collisions at the Relativistic Heavy Ion Collider
(RHIC) provide unique opportunities to study the spin structure of the nucleon.
We will highlight recent results on the nucleon spin structure from the STAR
and PHENIX experiments at RHIC: (1) A sizable gluon polarization in the proton
is measured with longitudinal double spin asymmetries of jet and hadron
production; (2) Longitudinal single spin asymmetries in W boson production
improve constraints on the sea quark polarization. The new spin asymmetry
results for W boson confirmed the SU(2) flavor asymmetry of the light sea quark
polarization in the proton; (3) Transverse spin effects in hadronic systems
offer new implications on parton distribution functions in the collinear and
transverse momentum dependent frameworks. We will also discuss near term plans
for the STAR forward detector upgrade and prospects for proton-proton and
proton-ion collisions in the years beyond 2021 at STAR.Comment: Proceedings for plenary talk at XLIX International Symposium on
Multiparticle Dynamics (ISMD2019
Spin alignment of vector meson in e+e- annihilation at Z0 pole
We calculate the spin density matrix of the vector meson produced in e+e-
annihilation at Z^0 pole. We show that the data imply a significant
polarization for the antiquark which is created in the fragmentation process of
the polarized initial quark and combines with the fragmenting quark to form the
vector meson. The direction of polarization is opposite to that of the
fragmenting quark and the magnitude is of the order of 0.5. A qualitative
explanation of this result based on the LUND string fragmentation model is
given.Comment: 15 pages, 2 fgiures; submitted to Phys. Rev.
Spin Alignment of Vector Meson in High Energy Reactions
The recent data on the polarization of vector meson at LEP show that the
vector mesons favor the helicity zero state. We calculate the helicity density
matrix of vector meson which contains a polarized fragmenting quark by adding
the spin of the fragmenting quark and that of the antiquark created in the
fragmentation. The data at LEP imply a significant polarization for the
antiquark in the opposite direction as that of the fragmenting quark. We extend
the calculations to other reactions and make predictions for vector mesons in
deeply inelastic lepton-nucleon scatterings and polarized collisions.Comment: 4 pages,3 figures, Talk given at 3rd Circum-Pan-Pacific Symposium on
"High Energy Spin Physics", Beijing, China, Oct.8-13, 200
Biholomorphic mappings on bounded starlike circular domains
AbstractLet Ω⊂Cn be a bounded starlike circular domain with 0∈Ω. In this paper, we introduce a class of holomorphic mappings Mg on Ω. Let f(z) be a normalized locally biholomorphic mapping on Ω such that Jf−1(z)f(z)∈Mg and z=0 is the zero of order k+1 of f(z)−z. We obtain a sharp growth theorem and sharp coefficient bounds for f(z). As applications, sharp distortion theorems for a subclass of starlike mappings are obtained. These results unify and generalize many known results
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