The spin structure function g_p^1 of the proton and a test of the Bjorken sum rule

Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68407700%3A21340%2F16%3A00235087" target="_blank" >RIV/68407700:21340/16:00235087 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.1016/j.physletb.2015.11.064" target="_blank" >http://dx.doi.org/10.1016/j.physletb.2015.11.064</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1016/j.physletb.2015.11.064" target="_blank" >10.1016/j.physletb.2015.11.064</a>

Result language
angličtina
Original language name
The spin structure function g_p^1 of the proton and a test of the Bjorken sum rule
Original language description
New results for the double spin asymmetry A1p and the proton longitudinal spin structure function g1p are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH 3 target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x . They improve the statistical precision of g1p(x) by about a factor of two in the region x<~0.02 . A next-to-leading order QCD fit to the g1 world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, ΔΣ, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g1p . The uncertainty of ΔΣ is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function g1NS(x,Q2) yields as ratio of the axial and vector coupling constants |gA/gV|=1.22±0.05 (stat.)±0.10 (syst.) , which validates the sum rule to an accuracy of about 9%.
Czech name
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Czech description
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Type
J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)
CEP classification
BF - Elementary particle theory and high energy physics
OECD FORD branch
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Project
Result was created during the realization of more than one project. More information in the Projects tab.
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year
2016
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

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