Publicação
Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data
| dc.contributor.author | COMPASS collaboration (221 authors) | |
| dc.contributor.author | Bordalo, P. | |
| dc.contributor.author | Franco, C. | |
| dc.contributor.author | Nunes, A.S. | |
| dc.contributor.author | Quaresma, M. | |
| dc.contributor.author | Quintans, C. | |
| dc.contributor.author | Ramos, S. | |
| dc.contributor.author | Silva, L. | |
| dc.contributor.author | Stolarski, M. | |
| dc.date.accessioned | 2019-02-04T08:50:22Z | |
| dc.date.available | 2019-02-04T08:50:22Z | |
| dc.date.issued | 2017-04-03 | |
| dc.date.updated | 2019-02-04T08:50:22Z | |
| dc.description.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 $Q^2>1~({\rm GeV}/c)^2$. 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 $p_{\rm T}$, the different $p_{\rm T}$-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 $\Delta g/g$ is evaluated at leading order in pQCD at a hard scale of $\mu^2= \langle Q^2 \rangle = 3 ({\rm GeV}/c)^2$. It is determined in three intervals of the nucleon momentum fraction carried by gluons, $x_{\rm g}$, covering the range $0.04 \!<\! x_{ \rm g}\! <\! 0.28$~ and does not exhibit a significant dependence on $x_{\rm g}$. The average over the three intervals, $\langle \Delta g/g \rangle = 0.113 \pm 0.038_{\rm (stat.)}\pm 0.036_{\rm (syst.)}$ at $\langle x_{\rm g} \rangle \approx 0.10$, suggests that the gluon polarisation is positive in the measured $x_{\rm g}$ range. | |
| dc.description.version | Peer Reviewed | |
| dc.identifier | Eur.Phys.J. C77 (2017) 209; DOI 10.1140/epjc/s10052-017-4716-x | |
| dc.identifier.uri | http://dx.doi.org/10.1140/epjc/s10052-017-4716-x | |
| dc.identifier.uri | http://hdl.handle.net/10400.26/26993 | |
| dc.language.iso | eng | |
| dc.title | Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data | |
| dc.type | journal article | |
| dspace.entity.type | Publication | |
| rcaap.rights | openAccess | pt |
| rcaap.type | article |