Longitudinal double-spin asymmetry A(1)(p) and spin-dependent structure function g(1)(p) of the proton at small values of x and Q(2)

0494616 - ÚPT 2019 RIV NL eng J - Journal Article
Aghasyan, M. - Alexeev, M. G. - Alexeev, G. D. - Srnka, Aleš … Total 228 authors
Longitudinal double-spin asymmetry A(1)(p) and spin-dependent structure function g(1)(p) of the proton at small values of x and Q(2).
Physics Letters. B. Roč. 781, JUN (2018), s. 464-472. ISSN 0370-2693. E-ISSN 1873-2445
R&D Projects: GA MŠMT(CZ) LO1212
Institutional support: RVO:68081731
Keywords : inelastic muon scattering * spin structure function * A(1) * g(1) * low x * low Q(2)
OECD category: Nuclear physics
Impact factor: 4.162, year: 2018

We present a precise measurement of the proton longitudinal double-spin asymmetry A(1)(p) and the proton spin-dependent structure function g(1)(P) at photon virtualities 0.006 (GeV/c)(2) < Q(2) < 1 (GeV/c)(2) in the Bjorken x range of 4 x 10(-5) < x < 4 x 10(-2). The results are based on data collected by the COMPASS Collaboration at CERN using muon beam energies of 160 GeV and 200 GeV. 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 A(1)(p) and g(1)(P) are found to be positive. It is for the first time that spin effects are found at such low values of x.
Permanent Link: http://hdl.handle.net/11104/0287724