Eur. Phys. J. C (2024) 84: 718
https://doi.org/10.1140/epjc/s10052-024-12987-0

Regular Article - Experimental Physics

Measurement of groomed event shape observables in deep-inelastic electron-proton scattering at HERA

¹ I. Physikalisches Institut der RWTH, Aachen, Germany
² University of Michigan, Ann Arbor, 48109, MI, USA
³ LAPP, Université de Savoie, CNRS/IN2P3, Annecy-le-Vieux, France
⁴ Inter-University Institute for High Energies ULB-VUB, Brussels, Belgium
⁵ Universiteit Antwerpen, Antwerp, Belgium
⁶ Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA
⁷ Department of Physics, University of the Basque Country UPV/EHU, 48080, Bilbao, Spain
⁸ School of Physics and Astronomy, University of Birmingham, Birmingham, UK
⁹ Horia Hulubei National Institute for R &D in Physics and Nuclear Engineering (IFIN-HH), Bucharest, Romania
¹⁰ University of Illinois, 60607, Chicago, IL, USA
¹¹ STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire, UK
¹² Institut für Physik, TU Dortmund, Dortmund, Germany
¹³ Institute for Particle Physics Phenomenology, Durham University, Durham, UK
¹⁴ CERN, Geneva, Switzerland
¹⁵ IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France
¹⁶ II. Physikalisches Institut, Universität Göttingen, Göttingen, Germany
¹⁷ Institut für Theoretische Physik, Universität Göttingen, Göttingen, Germany
¹⁸ Deutsches Elektronen-Synchrotron DESY, Hamburg and Zeuthen, Germany
¹⁹ Physikalisches Institut, Universität Heidelberg, Heidelberg, Germany
²⁰ Rice University, 77005-1827, Houston, TX, USA
²¹ Institute of Nuclear Physics Polish Academy of Sciences, Kraków, Poland
²² Department of Physics, University of Lancaster, Lancaster, UK
²³ Argonne National Laboratory, 60439, Lemont, IL, USA
²⁴ Department of Physics, University of Liverpool, Liverpool, UK
²⁵ School of Physics and Astronomy, Queen Mary University of London, London, UK
²⁶ CNRS/IN2P3, CPPM, Aix Marseille Univ, Marseille, France
²⁷ Max-Planck-Institut für Physik, Munich, Germany
²⁸ National Institute of Science Education and Research, Jatni, Odisha, India
²⁹ Joint Laboratory of Optics, Palacký University, Olomouc, Czech Republic
³⁰ IJCLab, CNRS/IN2P3, Université Paris-Saclay, Orsay, France
³¹ LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau, France
³² Faculty of Science, University of Montenegro, Podgorica, Montenegro
³³ Institute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic
³⁴ Faculty of Mathematics and Physics, Charles University, Praha, Czech Republic
³⁵ University of California, 92521, Riverside, CA, USA
³⁶ Dipartimento di Fisica Università di Roma Tre and INFN Roma 3, Rome, Italy
³⁷ Shandong University, Shandong, People’s Republic of China
³⁸ Fakultät IV-Department für Physik, Universität Siegen, Siegen, Germany
³⁹ Stony Brook University, 11794, Stony Brook, NY, USA
⁴⁰ Physics Department, University of Tennessee, 37996, Knoxville, TN, USA
⁴¹ Institute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
⁴² Ulaanbaatar University, Ulaanbaatar, Mongolia
⁴³ Brookhaven National Laboratory, 11973, Upton, NY, USA
⁴⁴ Paul Scherrer Institut, Villigen, Switzerland
⁴⁵ Department of Physics and Astronomy, Purdue University, 47907, West Lafayette, IN, USA
⁴⁶ Fachbereich C, Universität Wuppertal, Wuppertal, Germany
⁴⁷ Yerevan Physics Institute, Yerevan, Armenia
⁴⁸ Departamento de Fisica Aplicada, CINVESTAV, Mérida, Yucatán, Mexico
⁴⁹ Institut für Teilchenphysik, ETH, Zurich, Switzerland
⁵⁰ Physik-Institut der Universität Zürich, Zurich, Switzerland
⁵¹ Affiliated with an Institute Covered by a Current or Former Collaboration Agreement with DESY, Hamburg, Germany
⁵² Deutsches Elektronen-Synchrotron DESY, Hamburg and Zeuthen, Germany

^a stefan.schmitt@desy.de
^dz stefan.schmitt@desy.de

Received: 18 March 2024
Accepted: 3 June 2024
Published online: 22 July 2024

Abstract

The H1 Collaboration at HERA reports the first measurement of groomed event shape observables in deep inelastic electron-proton scattering (DIS) at $\sqrt{s}=319$GeV, using data recorded between the years 2003 and 2007 with an integrated luminosity of 351 ${\text{pb}}^{-1}$. Event shapes provide incisive probes of perturbative and non-perturbative QCD. Grooming techniques have been used for jet measurements in hadronic collisions; this paper presents the first application of grooming to DIS data. The analysis is carried out in the Breit frame, utilizing the novel Centauro jet clustering algorithm that is designed for DIS event topologies. Events are required to have squared momentum-transfer $Q^2>150$ GeV$_{}^2$ and inelasticity $0.2<y<0.7$. We report measurements of the production cross section of groomed event 1-jettiness and groomed invariant mass for several choices of grooming parameter. Monte Carlo model calculations and analytic calculations based on Soft Collinear Effective Theory are compared to the measurements.