Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q2>1 (GeV/c)2 . The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised 6 LiD target. By analysing the full range in hadron transverse momentum pT , the different pT -dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Δg/g is evaluated at leading order in pQCD at a hard scale of μ2=⟨Q2⟩=3(GeV/c)2 . It is determined in three intervals of the nucleon momentum fraction carried by gluons, xg , covering the range 0.04<xg<0.28 and does not exhibit a significant dependence on xg . The average over the three intervals, ⟨Δg/g⟩=0.113±0.038(stat.)±0.036(syst.) at ⟨xg⟩≈0.10 , suggests that the gluon polarisation is positive in the measured xg range.

Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data

Birsa, R.;Bradamante, F.;Bressan, A.;Dalla Torre, S.;Dasgupta, S. S.;Duic, V.;Levorato, S.;Makke, N.;Martin, A.;Matoušek, J.;Schiavon, P.;Sozzi, F.;Szabelski, A.;Takekawa, S.;
2017-01-01

Abstract

Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q2>1 (GeV/c)2 . The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised 6 LiD target. By analysing the full range in hadron transverse momentum pT , the different pT -dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Δg/g is evaluated at leading order in pQCD at a hard scale of μ2=⟨Q2⟩=3(GeV/c)2 . It is determined in three intervals of the nucleon momentum fraction carried by gluons, xg , covering the range 0.04
Pubblicato
https://link.springer.com/article/10.1140%2Fepjc%2Fs10052-017-4716-x
File in questo prodotto:
File Dimensione Formato  
2017_epjc77_209.pdf

accesso aperto

Descrizione: Articolo
Tipologia: Documento in Versione Editoriale
Licenza: Creative commons
Dimensione 829.41 kB
Formato Adobe PDF
829.41 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/11368/2919171
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 11
  • ???jsp.display-item.citation.isi??? 8
social impact