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Title: The polarized EMC effect

Abstract

We calculate both the spin independent and spin dependent nuclear structure functions in an effective quark theory. The nucleon is described as a composite quark-diquark state, and the nucleus is treated in the mean field approximation. We predict a sizable polarized EMC effect, which could be confirmed in future experiments.

Authors:
; ;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA
Sponsoring Org.:
USDOE - Office of Energy Research (ER)
OSTI Identifier:
912624
Report Number(s):
JLAB-THY-07-692; DOE/OR/23177-0115
TRN: US0800464
DOE Contract Number:
AC05-06OR23177
Resource Type:
Conference
Resource Relation:
Journal Name: AIP; Journal Volume: 892; Conference: The polarized EMC effect
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; EMC EFFECT; NUCLEAR STRUCTURE; NUCLEONS; QUARKS; SPIN

Citation Formats

W. Bentz, I. C. Cloet, and A. W. Thomas. The polarized EMC effect. United States: N. p., 2007. Web. doi:10.1063/1.2714385.
W. Bentz, I. C. Cloet, & A. W. Thomas. The polarized EMC effect. United States. doi:10.1063/1.2714385.
W. Bentz, I. C. Cloet, and A. W. Thomas. Thu . "The polarized EMC effect". United States. doi:10.1063/1.2714385. https://www.osti.gov/servlets/purl/912624.
@article{osti_912624,
title = {The polarized EMC effect},
author = {W. Bentz and I. C. Cloet and A. W. Thomas},
abstractNote = {We calculate both the spin independent and spin dependent nuclear structure functions in an effective quark theory. The nucleon is described as a composite quark-diquark state, and the nucleus is treated in the mean field approximation. We predict a sizable polarized EMC effect, which could be confirmed in future experiments.},
doi = {10.1063/1.2714385},
journal = {AIP},
number = ,
volume = 892,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}

Conference:
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  • The discovery of the EMC effect and the proton spin crisis by the European Muon Collaboration are two of the standout experiments of the last 25 years. It is therefore surprising that there has been no experimental and little theoretical investigation of the spin structure functions of atomic nuclei. To address this we present results for the spin-dependent structure functions of nuclei. The quark degrees of freedom in nuclei are accessed via the convolution formalism. Where the nucleon bound state is obtained by solving the relativistic Faddeev equation, and a relativistic shell model is used to model the atomic nucleus.more » We find the important result that the medium modifications to the polarized structure functions are about twice that of the unpolarized case.« less
  • By using a model for polarized parton densities that fits EMC data on polarized deep inelastic scattering, we make prediction for double helicity asymmetries in 1 and 2 jet inclusive production from polarized proton proton scattering at RHIC energies.
  • Updated results are presented on the measurement of the asymmetry parameter A{sub 1} and on the determination of the first moment of the spin-dependent structure function {ital g}{sub 1}, from deep inelastic polarized muon-proton scattering. Compared to the published results, a small amount of additional data have been included and a detailed reassessment made of the major sources of systematic error. The implications of the result for the spin structure of the nucleon are explored.
  • An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu-Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions, and find that we are readily able to reproduce both nuclear matter saturation and the experimental F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the EMC effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} differs significantly from 1, with the quenchingmore » caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which if confirmed experimentally, will reveal much about the quark structure of nuclear matter.« less
  • An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu-Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} differs significantly from unity,more » with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which, if confirmed experimentally, will reveal much about the quark structure of nuclear matter.« less