Eur. Phys. J. C (2017) 77: 791
https://doi.org/10.1140/epjc/s10052-017-5314-7

Regular Article - Experimental Physics

Determination of the strong coupling constant ${\mathit{\alpha }}_{\mathbf{s}}\mathbf{(}{\mathit{m}}_{\mathbf{Z}}\mathbf{)}$ in next-to-next-to-leading order QCD using H1 jet cross section measurements

H1 Collaboration

¹ I. Physikalisches Institut der RWTH, Aachen, Germany
² School of Physics and Astronomy, University of Birmingham, Birmingham, UK
³ Inter-University Institute for High Energies ULB-VUB, Brussels and Universiteit Antwerpen, Antwerp, Belgium
⁴ Horia Hulubei National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), Bucharest, Romania
⁵ STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
⁶ Institute of Nuclear Physics, Polish Academy of Sciences, 31342, Kraków, Poland
⁷ Institut für Physik, TU Dortmund, Dortmund, Germany
⁸ Joint Institute for Nuclear Research, Dubna, Russia
⁹ Irfu/SPP, CE Saclay, Gif-sur-Yvette, France
¹⁰ DESY, Hamburg, Germany
¹¹ Institut für Experimentalphysik, Universität Hamburg, Hamburg, Germany
¹² Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
¹³ Department of Physics, University of Lancaster, Lancaster, UK
¹⁴ Department of Physics, University of Liverpool, Liverpool, UK
¹⁵ School of Physics and Astronomy, Queen Mary University of London, London, UK
¹⁶ Aix Marseille Université, CNRS/IN2P3, CPPM UMR 7346, 13288, Marseille, France
¹⁷ Departamento de Fisica Aplicada, CINVESTAV, Mérida, Yucatán, Mexico
¹⁸ Institute for Theoretical and Experimental Physics, Moscow, Russia
¹⁹ Lebedev Physical Institute, Moscow, Russia
²⁰ Max-Planck-Institut für Physik, Munich, Germany
²¹ LAL, Université Paris-Sud, CNRS/IN2P3, Orsay, France
²² LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau, France
²³ Faculty of Science, University of Montenegro, Podgorica, Montenegro
²⁴ Institute of Physics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
²⁵ Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic
²⁶ Dipartimento di Fisica, Università di Roma Tre and INFN Roma 3, Rome, Italy
²⁷ Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria
²⁸ Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
²⁹ Paul Scherrer Institute, Villigen, Switzerland
³⁰ Fachbereich C, Universität Wuppertal, Wuppertal, Germany
³¹ Yerevan Physics Institute, Yerevan, Armenia
³² DESY, Zeuthen, Germany
³³ Institut für Teilchenphysik, ETH Zürich, Zurich, Switzerland
³⁴ Physik-Institut der Universität Zürich, Zurich, Switzerland
³⁵ IPNL, Université Claude Bernard Lyon 1, CNRS/IN2P3, Villeurbanne, France
³⁶ Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia
³⁷ CERN, Geneva, Switzerland
³⁸ Ulaanbaatar University, Ulaanbaatar, Mongolia
³⁹ Department of Physics, University of Toronto, M5S 1A7, Toronto, ON, Canada
⁴⁰ LAPP, Université de Savoie, CNRS/IN2P3, Annecy-le-Vieux, France
⁴¹ II. Physikalisches Institut, Universität Göttingen, Göttingen, Germany
⁴² Institute for Information Transmission Problems RAS, Moscow, Russia
⁴³ Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russian Federation
⁴⁴ Department of Physics, Oxford University, Oxford, UK
⁴⁵ Department of Physics and Astronomy, Purdue University, 525 Northwestern Ave, 47907, West Lafayette, IN, USA
⁴⁶ Department of Physics and Astronomy, Vrije University, De Boelelaan 1081, Amsterdam, The Netherlands
⁴⁷ National Institute for Subatomic Physics (NIKHEF), Science Park 105, Amsterdam, The Netherlands
⁴⁸ Institute for Particle Physics Phenomenology, Ogden Centre for Fundamental Physics, Durham University, South Road, Durham, UK
⁴⁹ Karlsruher Institut für Technologie (KIT), Institut für Experimentelle Teilchenphysik (ETP), Wolfgang-Gaede-Str. 1, Karlsruhe, Germany
⁵⁰ Department of Physics and Astronomy, University of Sussex, Pevensey II, Brighton, UK

^eb sschmitt@mail.desy.de

Received: 22 September 2017
Accepted: 12 October 2017
Published online: 22 November 2017

Abstract

The strong coupling constant ${\mathit{\alpha }}_{\mathrm{s}}$ is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic ep scattering (DIS) measured at HERA by the H1 collaboration using next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of ${\mathit{\alpha }}_{\mathrm{s}}(m_{\mathrm{Z}})$ at the Z-boson mass $m_Z$ are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be ${\mathit{\alpha }}_{\mathrm{s}}(m_{\mathrm{Z}})=0.1157{(20)}_{\exp }{(29)}_{\mathrm{th}}$. Complementary, ${\mathit{\alpha }}_{\mathrm{s}}(m_{\mathrm{Z}})$ is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value ${\mathit{\alpha }}_{\mathrm{s}}(m_{\mathrm{Z}})=0.1142{(28)}_{\mathrm{tot}}$ obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.