https://doi.org/10.1140/epjc/s10052-017-4716-x
Regular Article - Experimental Physics
Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data
1
Department of Physics, University of Aveiro, 3810-193, Aveiro, Portugal
2
Institut für Experimentalphysik, Universität Bochum, 44780, Bochum, Germany
3
Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, 53115, Bonn, Germany
4
Physikalisches Institut, Universität Bonn, 53115, Bonn, Germany
5
Institute of Scientific Instruments, AS CR, 61264, Brno, Czech Republic
6
Matrivani Institute of Experimental Research and Education, Calcutta, 700 030, India
7
Joint Institute for Nuclear Research, 141980, Dubna, Moscow region, Russia
8
Physikalisches Institut, Universität Erlangen–Nürnberg, 91054, Erlangen, Germany
9
Physikalisches Institut, Universität Freiburg, 79104, Freiburg, Germany
10
CERN, 1211, Geneva 23, Switzerland
11
Technical University in Liberec, 46117, Liberec, Czech Republic
12
LIP, 1000-149, Lisbon, Portugal
13
Institut für Kernphysik, Universität Mainz, 55099, Mainz, Germany
14
University of Miyazaki, Miyazaki, 889-2192, Japan
15
Lebedev Physical Institute, 119991, Moscow, Russia
16
Physik Department, Technische Universität München, 85748, Garching, Germany
17
Nagoya University, 464, Nagoya, Japan
18
Faculty of Mathematics and Physics, Charles University in Prague, 18000, Prague, Czech Republic
19
Czech Technical University in Prague, 16636, Prague, Czech Republic
20
State Scientific Center Institute for High Energy Physics of National Research Center ‘Kurchatov Institute’, 142281, Protvino, Russia
21
CEA IRFU/SPhN Saclay, 91191, Gif-sur-Yvette, France
22
Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan
23
School of Physics and Astronomy, Tel Aviv University, 69978, Tel Aviv, Israel
24
Department of Physics, University of Trieste, 34127, Trieste, Italy
25
Trieste Section of INFN, 34127, Trieste, Italy
26
Abdus Salam ICTP, 34151, Trieste, Italy
27
Department of Physics, University of Turin, 10125, Turin, Italy
28
Torino Section of INFN, 10125, Turin, Italy
29
Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL, 61801-3080, USA
30
National Centre for Nuclear Research, 00-681, Warsaw, Poland
31
Faculty of Physics, University of Warsaw, 02-093, Warsaw, Poland
32
Institute of Radioelectronics, Warsaw University of Technology, 00-665, Warsaw, Poland
33
Yamagata University, Yamagata, 992-8510, Japan
34
Retired from Ludwig-Maximilians-Universität München, Department für Physik, 80799, Munich, Germany
35
CERN, 1211, Geneva 23, Switzerland
* e-mail: oleg.denisov@cern.ch
** e-mail: gerhard.mallot@cern.ch
*** e-mail: marcin.stolarski@cern.ch
Received:
20
September
2016
Accepted:
16
February
2017
Published online:
3
April
2017
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 . The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised
LiD target. By analysing the full range in hadron transverse momentum
, the different
-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
is evaluated at leading order in pQCD at a hard scale of
. It is determined in three intervals of the nucleon momentum fraction carried by gluons,
, covering the range
and does not exhibit a significant dependence on
. The average over the three intervals,
at
, suggests that the gluon polarisation is positive in the measured
range.
© The Author(s), 2017