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, Sergey Alexandrovich Mamon

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


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
Publication statusPublished - 10 Jun 2018


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

ASJC Scopus subject areas

  • Nuclear and High Energy Physics

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