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Title: Study of Λ hyperon production in the HERMES experiment

Abstract

Semi-inclusive A hyperon production has been studied in the HERMES experiment using the E e = 27.5 GeV polarized positron beam incident on polarized or unpolarized internal gas target. The multiplicity distribution over fractional A energy z has been investigated and the fragmentation function D u Λ (z) has been extracted. The D u Λ (z) found by HERMES is well described with the help of the parametrization based on the experiments on A production in high energy proton-proton collisions, but it is substantially smaller then that deduced from the e + e - annihilation data. The distribution over A transverse momentum squared p T 2 has also been analyzed. The results show that at z > 0.2 the p T 2 distribution is dominated by the quark transverse motion in the fragmentation process. The longitudinal spin transfer from the beam to the A has been measured. The systematic uncertainty of the spin transfer has been reduced by reversal of the beam polarization several times during the data taking period. The spin transfer coefficient is found to be S Λ = 0.04±0.08(stat)±0.03(syst) at an average fractional energy of the produced A hyperons of $$\langle{z}$$$\rangle$$= 0.45. The dependence of the longitudinal spin transfer on z is presented and compared with recent theoretical calculations.

Authors:
 [1];  [1];  [2]
  1. Petersburg Nuclear Physics Inst., Catchina (Russia)
  2. Petersburg Nuclear Physics Inst., Catchina (Russia); et al.
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
Contributing Org.:
HERMES Collaboration
OSTI Identifier:
1407030
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Acta Physica Polonica. Series B
Additional Journal Information:
Journal Volume: 33; Journal ID: ISSN 0587-4254
Publisher:
Jagiellonian University
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS

Citation Formats

Belostotski, S., Grebenyuk, O., and Naryshkin, Y. Study of Λ hyperon production in the HERMES experiment. United States: N. p., 2002. Web.
Belostotski, S., Grebenyuk, O., & Naryshkin, Y. Study of Λ hyperon production in the HERMES experiment. United States.
Belostotski, S., Grebenyuk, O., and Naryshkin, Y. Fri . "Study of Λ hyperon production in the HERMES experiment". United States. https://www.osti.gov/servlets/purl/1407030.
@article{osti_1407030,
title = {Study of Λ hyperon production in the HERMES experiment},
author = {Belostotski, S. and Grebenyuk, O. and Naryshkin, Y.},
abstractNote = {Semi-inclusive A hyperon production has been studied in the HERMES experiment using the E e = 27.5 GeV polarized positron beam incident on polarized or unpolarized internal gas target. The multiplicity distribution over fractional A energy z has been investigated and the fragmentation function D u Λ (z) has been extracted. The D u Λ (z) found by HERMES is well described with the help of the parametrization based on the experiments on A production in high energy proton-proton collisions, but it is substantially smaller then that deduced from the e + e - annihilation data. The distribution over A transverse momentum squared p T 2 has also been analyzed. The results show that at z > 0.2 the p T 2 distribution is dominated by the quark transverse motion in the fragmentation process. The longitudinal spin transfer from the beam to the A has been measured. The systematic uncertainty of the spin transfer has been reduced by reversal of the beam polarization several times during the data taking period. The spin transfer coefficient is found to be S Λ = 0.04±0.08(stat)±0.03(syst) at an average fractional energy of the produced A hyperons of $\langle{z}$$\rangle$= 0.45. The dependence of the longitudinal spin transfer on z is presented and compared with recent theoretical calculations.},
doi = {},
journal = {Acta Physica Polonica. Series B},
number = ,
volume = 33,
place = {United States},
year = {2002},
month = {11}
}

Journal Article:
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