skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Spin asymmetries and correlations in {lambda}-pair production through the radiative return method

Abstract

Exclusive baryon pair production through the radiative return is a unique tool to determine the electric and the magnetic form factors in the timelike region over a wide range of energies. The decay of {lambda}-baryons into p+{pi}{sup -} can be used to measure their spin and to analyze spin-spin correlations in the {lambda}{lambda} system. We evaluate the spin dependent hadronic tensor, which describes this reaction, calculate the corresponding cross section for e{sup +}e{sup -}{yields}{lambda}{lambda} and e{sup +}e{sup -}{yields}{lambda}{lambda}{gamma} with subsequent decays of {lambda} and {lambda} and present a compact formula for the correlated distribution. We demonstrate that the relative phase between the electric and the magnetic form factor can be determined in this analysis by considering single-spin asymmetries and correlated decay distributions. The reaction is implemented in the event generator PHOKHARA. It is demonstrated that the relative phase can be measured with the event sample presently accumulated at B- factories.

Authors:
; ;  [1];  [2]
  1. Institute of Physics, University of Silesia, PL-40007 Katowice (Poland)
  2. (Germany)
Publication Date:
OSTI Identifier:
21020286
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. D, Particles Fields; Journal Volume: 75; Journal Issue: 7; Other Information: DOI: 10.1103/PhysRevD.75.074026; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ASYMMETRY; CORRELATIONS; CROSS SECTIONS; DISTRIBUTION; ELECTRON-POSITRON INTERACTIONS; ELECTRONS; EXCLUSIVE INTERACTIONS; FORM FACTORS; HADRONIC PARTICLE DECAY; LAMBDA BARYONS; PAIR PRODUCTION; PIONS MINUS; POSITRONS; SPIN; TENSORS

Citation Formats

Czyz, Henryk, Grzelinska, Agnieszka, Kuehn, Johann H., and Institut fuer Theoretische Teilchenphysik, Universitaet Karlsruhe, D-76128 Karlsruhe. Spin asymmetries and correlations in {lambda}-pair production through the radiative return method. United States: N. p., 2007. Web. doi:10.1103/PHYSREVD.75.074026.
Czyz, Henryk, Grzelinska, Agnieszka, Kuehn, Johann H., & Institut fuer Theoretische Teilchenphysik, Universitaet Karlsruhe, D-76128 Karlsruhe. Spin asymmetries and correlations in {lambda}-pair production through the radiative return method. United States. doi:10.1103/PHYSREVD.75.074026.
Czyz, Henryk, Grzelinska, Agnieszka, Kuehn, Johann H., and Institut fuer Theoretische Teilchenphysik, Universitaet Karlsruhe, D-76128 Karlsruhe. Sun . "Spin asymmetries and correlations in {lambda}-pair production through the radiative return method". United States. doi:10.1103/PHYSREVD.75.074026.
@article{osti_21020286,
title = {Spin asymmetries and correlations in {lambda}-pair production through the radiative return method},
author = {Czyz, Henryk and Grzelinska, Agnieszka and Kuehn, Johann H. and Institut fuer Theoretische Teilchenphysik, Universitaet Karlsruhe, D-76128 Karlsruhe},
abstractNote = {Exclusive baryon pair production through the radiative return is a unique tool to determine the electric and the magnetic form factors in the timelike region over a wide range of energies. The decay of {lambda}-baryons into p+{pi}{sup -} can be used to measure their spin and to analyze spin-spin correlations in the {lambda}{lambda} system. We evaluate the spin dependent hadronic tensor, which describes this reaction, calculate the corresponding cross section for e{sup +}e{sup -}{yields}{lambda}{lambda} and e{sup +}e{sup -}{yields}{lambda}{lambda}{gamma} with subsequent decays of {lambda} and {lambda} and present a compact formula for the correlated distribution. We demonstrate that the relative phase between the electric and the magnetic form factor can be determined in this analysis by considering single-spin asymmetries and correlated decay distributions. The reaction is implemented in the event generator PHOKHARA. It is demonstrated that the relative phase can be measured with the event sample presently accumulated at B- factories.},
doi = {10.1103/PHYSREVD.75.074026},
journal = {Physical Review. D, Particles Fields},
number = 7,
volume = 75,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • We calculate, for the first time, the spin-spin asymmetry A/sub L/L=dsigma ( p (+) p (+) ..-->.. (..mu../sup -/..mu../sup +/) X)-dsigma ( p ( +) p (-) ..-->.. (..mu../sup -/..mu../sup +/) X) dsigma ( p (+) p (+) ..-->.. (..mu../sup -/..mu../sup +/) X) +dsigma ( p (+) p (-) ..-->.. (..mu../sup -/..mu../sup +/) X) in the production of lepton pairs at large p/sub T/ from longitudinally polarized hadron beam and target using a hard-scattering model and quantum-chromodynamic perturbation theory. Asymmetries at the 5--10% level are predicted for p/sub T/ > or approx. = 1 GeV/c. Experimental tests should be possiblemore » in the near future.« less
  • We study the single spin asymmetries for the D-meson production, Drell-Yan lepton-pair production and the direct-photon production in the pp collision induced by the twist-3 three-gluon correlation functions in the transversely polarized nucleon. We present a corresponding polarized cross section formula in the leading-order with respect to the QCD coupling and a model calculation for the asymmetries, illustrating the sensitivity to the form of the correlation functions.
  • Theoretical analyses of polarized leptoproduction data suggest that the polarized gluon structure function might be large, but there has been no independent measurement of this quantity. Measurements of single-spin asymmetries in the production of muon pairs from the scattering of two protons, one of which is longitudinally polarized, can be interpreted in terms of polarized gluon, quark, and antiquark structure functions. We develop this interpretation in detail and compute the size of the asymmetries that might be expected for this process.
  • We discuss the double-spin asymmetries in transversely polarized Drell-Yan process, calculating all-order gluon resummation corrections up to the next-to-leading logarithmic accuracy. This resummation is relevant when the transverse-momentum Q{sub T} of the produced lepton pair is small, and reproduces the (fixed-order) next-to-leading QCD corrections upon integrating over Q{sub T}. The resummation corrections in pp-bar-collision behave differently compared with pp-collision cases, and are small at the kinematics in the proposed GSI experiments. This fact allows us to predict large value of the double-spin asymmetries at GSI, using recent empirical information on the transversity.