Longitudinal double-spin asymmetry A1 p and spin-dependent structure function g1 p of the proton at small values of x and Q2

COMPASS Collaboration

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

We present a precise measurement of the proton longitudinal double-spin asymmetry A1 p and the proton spin-dependent structure function g1 p at photon virtualities 0.006(GeV/c)2<Q2<1(GeV/c)2 in the Bjorken x range of 4×10−5<x<4×10−2. The results are based on data collected by the COMPASS Collaboration at CERN using muon beam energies of 160GeV and 200GeV. The statistical precision is more than tenfold better than that of the previous measurement in this region. In the whole range of x, the measured values of A1 p and g1 p are found to be positive. It is for the first time that spin effects are found at such low values of x.

Original languageEnglish
Pages (from-to)464-472
Number of pages9
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Volume781
DOIs
StatePublished - 10 Jun 2018

Funding

FundersFunder number
Israel Academy of Sciences and Humanities
Bundesministerium für Bildung und Frauen
Ministry of Education, Culture, Sports, Science and Technology
National Science Foundation1506416
National Science Foundation
Japan Society for the Promotion of Science18002006, 20540299, 26247032, 18540281
Japan Society for the Promotion of Science
Fundação para a Ciência e a TecnologiaCERN/FP 116376/2010, 123600/2011, CERN/FIS-NUC/0017/2015
Fundação para a Ciência e a Tecnologia
Narodowe Centrum Nauki2015/18/M/ST2/00550
Narodowe Centrum Nauki
California Department of Fish and Wildlife1102, 2044
California Department of Fish and Wildlife
Seventh Framework Programme283286
Seventh Framework Programme
Ministry of Education, Youth and ScienceLG13031
Ministry of Education, Youth and Science

    Keywords

    • A
    • Inelastic muon scattering
    • Low Q
    • Low x
    • Spin structure function
    • g

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