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

C. Adolph; M. Aghasyan; R. Akhunzyanov; M. G. Alexeev; G. D. Alexeev; A. Amoroso; V. Andrieux; N. V. Anfimov; V. Anosov; W. Augustyniak; A. Austregesilo; C. D. R. Azevedo; B. Badełek; F. Balestra; J. Barth; R. Beck; Y. Bedfer; J. Bernhard; K. Bicker; E. R. Bielert; R. Birsa; J. Bisplinghoff; M. Bodlak; M. Boer; P. Bordalo; F. Bradamante; C. Braun; A. Bressan; M. Büchele; W.-C. Chang; M. Chiosso; I. Choi; S.-U. Chung; A. Cicuttin; M. L. Crespo; Q. Curiel; S. Dalla Torre; S. S. Dasgupta; S. Dasgupta; O. Yu. Denisov; L. Dhara; S. V. Donskov; N. Doshita; V. Duic; W. Dünnweber; M. Dziewiecki; A. Efremov; P. D. Eversheim; W. Eyrich; M. Faessler; A. Ferrero; M. Finger; M. Finger jr.; H. Fischer; C. Franco; N. du Fresne von Hohenesche; J. M. Friedrich; V. Frolov; E. Fuchey; F. Gautheron; O. P. Gavrichtchouk; S. Gerassimov; F. Giordano; I. Gnesi; M. Gorzellik; S. Grabmüller; A. Grasso; M. Grosse Perdekamp; B. Grube; T. Grussenmeyer; A. Guskov; F. Haas; D. Hahne; D. von Harrach; R. Hashimoto; F. H. Heinsius; R. Heitz; F. Herrmann; F. Hinterberger; N. Horikawa; N. d’Hose; C.-Y. Hsieh; S. Huber; S. Ishimoto; A. Ivanov; Yu. Ivanshin; T. Iwata; R. Jahn; V. Jary; R. Joosten; P. Jörg; E. Kabuß; B. Ketzer; G. V. Khaustov; Yu. A. Khokhlov; Yu. Kisselev; F. Klein; K. Klimaszewski; J. H. Koivuniemi; V. N. Kolosov; K. Kondo; K. Königsmann; I. Konorov; V. F. Konstantinov; A. M. Kotzinian; O. M. Kouznetsov; M. Krämer; P. Kremser; F. Krinner; Z. V. Kroumchtein; Y. Kulinich; F. Kunne; K. Kurek; R. P. Kurjata; A. A. Lednev; A. Lehmann; M. Levillain; S. Levorato; J. Lichtenstadt; R. Longo; A. Maggiora; A. Magnon; N. Makins; N. Makke; G. K. Mallot; C. Marchand; B. Marianski; A. Martin; J. Marzec; J. Matoušek; H. Matsuda; T. Matsuda; G. V. Meshcheryakov; W. Meyer; T. Michigami; Yu. V. Mikhailov; M. Mikhasenko; Y. Miyachi; P. Montuenga; A. Nagaytsev; F. Nerling; D. Neyret; V. I. Nikolaenko; J. Nový; W.-D. Nowak; G. Nukazuka; A. S. Nunes; A. G. Olshevsky; I. Orlov; M. Ostrick; D. Panzieri; B. Parsamyan; S. Paul; J.-C. Peng; F. Pereira; M. Pešek; D. V. Peshekhonov; S. Platchkov; J. Pochodzalla; V. A. Polyakov; J. Pretz; M. Quaresma; C. Quintans; S. Ramos; C. Regali; G. Reicherz; C. Riedl; M. Roskot; N. S. Rossiyskaya; D. I. Ryabchikov; A. Rybnikov; A. Rychter; R. Salac; V. D. Samoylenko; A. Sandacz; C. Santos; S. Sarkar; I. A. Savin; T. Sawada; G. Sbrizzai; P. Schiavon; K. Schmidt; H. Schmieden; K. Schönning; S. Schopferer; E. Seder; A. Selyunin; O. Yu. Shevchenko; L. Silva; L. Sinha; S. Sirtl; M. Slunecka; J. Smolik; F. Sozzi; A. Srnka; M. Stolarski; M. Sulc; H. Suzuki; A. Szabelski; T. Szameitat; P. Sznajder; S. Takekawa; M. Tasevsky; S. Tessaro; F. Tessarotto; F. Thibaud; F. Tosello; V. Tskhay; S. Uhl; J. Veloso; M. Virius; J. Vondra; T. Weisrock; M. Wilfert; J. ter Wolbeek; K. Zaremba; P. Zavada; M. Zavertyaev; E. Zemlyanichkina; M. Ziembicki; A. Zink

doi:10.1140/epjc/s10052-017-4716-x

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2017) 77: 209
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

C. Adolph⁸, M. Aghasyan²⁵, R. Akhunzyanov⁷, M. G. Alexeev²⁷, G. D. Alexeev⁷, A. Amoroso²⁷^,28, V. Andrieux²¹, N. V. Anfimov⁷, V. Anosov⁷, W. Augustyniak³⁰, A. Austregesilo¹⁶, C. D. R. Azevedo¹, B. Badełek³¹, F. Balestra²⁷^,28, J. Barth⁴, R. Beck³, Y. Bedfer¹⁰^,21, J. Bernhard¹⁰^,13, K. Bicker¹⁰^,16, E. R. Bielert¹⁰, R. Birsa²⁵, J. Bisplinghoff³, M. Bodlak¹⁸, M. Boer²¹, P. Bordalo¹², F. Bradamante²⁴^,25, C. Braun⁸, A. Bressan²⁴^,25, M. Büchele⁹, W.-C. Chang²², M. Chiosso²⁷^,28, I. Choi²⁹, S.-U. Chung¹⁶, A. Cicuttin²⁵^,26, M. L. Crespo²⁵^,26, Q. Curiel²¹, S. Dalla Torre²⁵, S. S. Dasgupta⁶, S. Dasgupta²⁴^,25, O. Yu. Denisov²⁸, L. Dhara⁶, S. V. Donskov²⁰, N. Doshita³³, V. Duic²⁴, W. Dünnweber³⁴, M. Dziewiecki³², A. Efremov⁷, P. D. Eversheim³, W. Eyrich⁸, M. Faessler³⁴, A. Ferrero²¹, M. Finger¹⁸, M. Finger jr.¹⁸, H. Fischer⁹, C. Franco¹², N. du Fresne von Hohenesche¹³, J. M. Friedrich¹⁶, V. Frolov⁷^,10, E. Fuchey²¹, F. Gautheron², O. P. Gavrichtchouk⁷, S. Gerassimov¹⁵^,16, F. Giordano²⁹, I. Gnesi²⁷^,28, M. Gorzellik⁹, S. Grabmüller¹⁶, A. Grasso²⁷^,28, M. Grosse Perdekamp²⁹, B. Grube¹⁶, T. Grussenmeyer⁹, A. Guskov⁷, F. Haas¹⁶, D. Hahne⁴, D. von Harrach¹³, R. Hashimoto³³, F. H. Heinsius⁹, R. Heitz²⁹, F. Herrmann⁹, F. Hinterberger³, N. Horikawa¹⁷, N. d’Hose²¹, C.-Y. Hsieh²², S. Huber¹⁶, S. Ishimoto³³, A. Ivanov²⁷^,28, Yu. Ivanshin⁷, T. Iwata³³, R. Jahn³, V. Jary¹⁹, R. Joosten³, P. Jörg⁹, E. Kabuß¹³, B. Ketzer³, G. V. Khaustov²⁰, Yu. A. Khokhlov²⁰, Yu. Kisselev⁷, F. Klein⁴, K. Klimaszewski³⁰, J. H. Koivuniemi², V. N. Kolosov²⁰, K. Kondo³³, K. Königsmann⁹, I. Konorov¹⁵^,16, V. F. Konstantinov²⁰, A. M. Kotzinian²⁷^,28, O. M. Kouznetsov⁷, M. Krämer¹⁶, P. Kremser⁹, F. Krinner¹⁶, Z. V. Kroumchtein⁷, Y. Kulinich²⁹, F. Kunne²¹, K. Kurek³⁰, R. P. Kurjata³², A. A. Lednev²⁰, A. Lehmann⁸, M. Levillain²¹, S. Levorato²⁵, J. Lichtenstadt²³, R. Longo²⁷^,28, A. Maggiora²⁸, A. Magnon²¹, N. Makins²⁹, N. Makke²⁴^,25, G. K. Mallot¹⁰, C. Marchand²¹, B. Marianski³⁰, A. Martin²⁴^,25, J. Marzec³², J. Matoušek¹⁸, H. Matsuda³³, T. Matsuda¹⁴, G. V. Meshcheryakov⁷, W. Meyer², T. Michigami³³, Yu. V. Mikhailov²⁰, M. Mikhasenko³, Y. Miyachi³³, P. Montuenga²⁹, A. Nagaytsev⁷, F. Nerling¹³, D. Neyret²¹, V. I. Nikolaenko²⁰, J. Nový¹⁰^,19, W.-D. Nowak⁹, G. Nukazuka³³, A. S. Nunes¹², A. G. Olshevsky⁷, I. Orlov⁷, M. Ostrick¹³, D. Panzieri²⁸, B. Parsamyan²⁷^,28, S. Paul¹⁶, J.-C. Peng²⁹, F. Pereira¹, M. Pešek¹⁸, D. V. Peshekhonov⁷, S. Platchkov²¹, J. Pochodzalla¹³, V. A. Polyakov²⁰, J. Pretz⁴, M. Quaresma¹², C. Quintans¹², S. Ramos¹², C. Regali⁹, G. Reicherz², C. Riedl²⁹, M. Roskot¹⁸, N. S. Rossiyskaya⁷, D. I. Ryabchikov²⁰, A. Rybnikov⁷, A. Rychter³², R. Salac¹⁹, V. D. Samoylenko²⁰, A. Sandacz³⁰, C. Santos²⁵, S. Sarkar⁶, I. A. Savin⁷, T. Sawada²², G. Sbrizzai²⁴^,25, P. Schiavon²⁴^,25, K. Schmidt⁹, H. Schmieden⁴, K. Schönning¹⁰, S. Schopferer⁹, E. Seder²¹, A. Selyunin⁷, O. Yu. Shevchenko⁷, L. Silva¹², L. Sinha⁶, S. Sirtl⁹, M. Slunecka⁷, J. Smolik⁷, F. Sozzi²⁵, A. Srnka⁵, M. Stolarski¹², M. Sulc¹¹, H. Suzuki³³, A. Szabelski³⁰, T. Szameitat⁹, P. Sznajder³⁰, S. Takekawa²⁷^,28, M. Tasevsky⁷, S. Tessaro²⁵, F. Tessarotto²⁵, F. Thibaud²¹, F. Tosello²⁸, V. Tskhay¹⁵, S. Uhl¹⁶, J. Veloso¹, M. Virius¹⁹, J. Vondra¹⁹, T. Weisrock¹³, M. Wilfert¹³, J. ter Wolbeek⁹, K. Zaremba³², P. Zavada⁷, M. Zavertyaev¹⁵, E. Zemlyanichkina⁷, M. Ziembicki³², A. Zink⁸ and COMPASS Collaboration

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

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 $Q^2>1~(\mathrm{GeV}/c)^2$ . 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 $p_\mathrm{T}$ , the different $p_\mathrm{T}$ -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 $\mu ^2= \langle Q^2 \rangle = 3 (\mathrm{GeV}/c)^2$ . It is determined in three intervals of the nucleon momentum fraction carried by gluons, $x_\mathrm{g}$ , covering the range $0.04 \!<\! x_{ \mathrm g}\! <\! 0.28$ and does not exhibit a significant dependence on $x_\mathrm{g}$ . The average over the three intervals, $\langle \Delta g/g \rangle = 0.113 \pm 0.038_\mathrm{(stat.)}\pm 0.036_\mathrm{(syst.)}$ at $\langle x_\mathrm{g} \rangle \approx 0.10$ , suggests that the gluon polarisation is positive in the measured $x_\mathrm{g}$ range.