We present a precise measurement of the proton longitudinal double-spin asymmetry A1p and the proton spin-dependent structure function g1p at photon virtualities 0.006(GeV/c)2<1(GeV/c)2 in the Bjorken x range of 4×10−5<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 A1p and g1p are found to be positive. It is for the first time that spin effects are found at such low values of x.

Longitudinal double-spin asymmetry A1p and spin-dependent structure function g1p of the proton at small values of x and Q2

Ball M.;Bressan A.;Capozza L.;Chiosso M.;Grasso A.;Panzieri D.;Parsamyan B.;Paul S.;Pierre N.;Schmidt K.;Tessaro S.;Vidon A.;
2018-01-01

Abstract

We present a precise measurement of the proton longitudinal double-spin asymmetry A1p and the proton spin-dependent structure function g1p at photon virtualities 0.006(GeV/c)2<1(GeV/c)2 in the Bjorken x range of 4×10−5<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 A1p and g1p are found to be positive. It is for the first time that spin effects are found at such low values of x.
File in questo prodotto:
File Dimensione Formato  
2018_plb781_464.pdf

file ad accesso aperto

Licenza: Dominio pubblico
Dimensione 603.76 kB
Formato Adobe PDF
603.76 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11579/111570
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 23
  • ???jsp.display-item.citation.isi??? 18
social impact