Search for QCD instanton-induced processes at HERA in the high- domain

V. Andreev; A. Baghdasaryan; K. Begzsuren; A. Belousov; A. Bolz; V. Boudry; G. Brandt; V. Brisson; D. Britzger; A. Buniatyan; A. Bylinkin; L. Bystritskaya; A. J. Campbell; K. B. Cantun Avila; K. Cerny; V. Chekelian; J. G. Contreras; J. Cvach; J. B. Dainton; K. Daum; C. Diaconu; M. Dobre; V. Dodonov; G. Eckerlin; S. Egli; E. Elsen; L. Favart; A. Fedotov; J. Feltesse; J. Ferencei; M. Fleischer; A. Fomenko; E. Gabathuler; J. Gayler; S. Ghazaryan; L. Goerlich; N. Gogitidze; M. Gouzevitch; C. Grab; A. Grebenyuk; T. Greenshaw; G. Grindhammer; D. Haidt; R. C. W. Henderson; J. Hladkỳ; D. Hoffmann; R. Horisberger; T. Hreus; F. Huber; M. Jacquet; X. Janssen; H. Jung; M. Kapichine; J. Katzy; C. Kiesling; M. Klein; C. Kleinwort; R. Kogler; P. Kostka; J. Kretzschmar; D. Krücker; K. Krüger; M. P. J. Landon; W. Lange; P. Laycock; A. Lebedev; S. Levonian; K. Lipka; B. List; J. List; B. Lobodzinski; E. Malinovski; H.-U. Martyn; S. J. Maxfield; A. Mehta; A. B. Meyer; H. Meyer; J. Meyer; S. Mikocki; A. Morozov; K. Müller; Th. Naumann; P. R. Newman; C. Niebuhr; G. Nowak; J. E. Olsson; D. Ozerov; C. Pascaud; G. D. Patel; E. Perez; A. Petrukhin; I. Picuric; H. Pirumov; D. Pitzl; R. Plačakytė; B. Pokorny; R. Polifka; V. Radescu; N. Raicevic; T. Ravdandorj; P. Reimer; E. Rizvi; P. Robmann; R. Roosen; A. Rostovtsev; M. Rotaru; S. Rusakov; D. Šálek; D. P. C. Sankey; M. Sauter; E. Sauvan; S. Schmitt; L. Schoeffel; A. Schöning; F. Sefkow; S. Shushkevich; Y. Soloviev; P. Sopicki; D. South; V. Spaskov; A. Specka; M. Steder; B. Stella; U. Straumann; T. Sykora; P. D. Thompson; D. Traynor; P. Truöl; I. Tsakov; B. Tseepeldorj; J. Turnau; A. Valkárová; C. Vallée; P. Van Mechelen; Y. Vazdik; D. Wegener; E. Wünsch; J. Žáček; Z. Zhang; R. Žlebčík; H. Zohrabyan; F. Zomer

doi:10.1140/epjc/s10052-016-4194-6

2021 Impact factor 4.991

Particles and Fields

Open Access

Eur. Phys. J. C (2016) 76: 381
https://doi.org/10.1140/epjc/s10052-016-4194-6

Regular Article - Experimental Physics

H1 Collaboration

V. Andreev¹⁹, A. Baghdasaryan³¹, K. Begzsuren²⁸, A. Belousov¹⁹, A. Bolz¹², V. Boudry²², G. Brandt⁴¹, V. Brisson²¹, D. Britzger¹⁰, A. Buniatyan², A. Bylinkin⁴³, L. Bystritskaya¹⁸, A. J. Campbell¹⁰, K. B. Cantun Avila¹⁷, K. Cerny²⁵, V. Chekelian²⁰, J. G. Contreras¹⁷, J. Cvach²⁴, J. B. Dainton¹⁴, K. Daum³⁰, C. Diaconu¹⁶, M. Dobre⁴, V. Dodonov¹⁰, G. Eckerlin¹⁰, S. Egli²⁹, E. Elsen¹⁰, L. Favart³, A. Fedotov¹⁸, J. Feltesse⁹, J. Ferencei⁴⁴, M. Fleischer¹⁰, A. Fomenko¹⁹, E. Gabathuler¹⁴, J. Gayler¹⁰, S. Ghazaryan¹⁰, L. Goerlich⁶, N. Gogitidze¹⁹, M. Gouzevitch³⁵, C. Grab³³, A. Grebenyuk³, T. Greenshaw¹⁴, G. Grindhammer²⁰, D. Haidt¹⁰, R. C. W. Henderson¹³, J. Hladkỳ²⁴, D. Hoffmann¹⁶, R. Horisberger²⁹, T. Hreus³, F. Huber¹², M. Jacquet²¹, X. Janssen³, H. Jung³^,10, M. Kapichine⁸, J. Katzy¹⁰, C. Kiesling²⁰, M. Klein¹⁴, C. Kleinwort¹⁰, R. Kogler¹¹, P. Kostka¹⁴, J. Kretzschmar¹⁴, D. Krücker¹⁰, K. Krüger¹⁰, M. P. J. Landon¹⁵, W. Lange³², P. Laycock¹⁴, A. Lebedev¹⁹, S. Levonian¹⁰, K. Lipka¹⁰, B. List¹⁰, J. List¹⁰, B. Lobodzinski²⁰, E. Malinovski¹⁹, H.-U. Martyn¹, S. J. Maxfield¹⁴, A. Mehta¹⁴, A. B. Meyer¹⁰, H. Meyer³⁰, J. Meyer¹⁰, S. Mikocki⁶, A. Morozov⁸, K. Müller³⁴, Th. Naumann³², P. R. Newman², C. Niebuhr¹⁰, G. Nowak⁶, J. E. Olsson¹⁰, D. Ozerov²⁹, C. Pascaud²¹, G. D. Patel¹⁴, E. Perez³⁷, A. Petrukhin³⁵, I. Picuric²³, H. Pirumov¹⁰, D. Pitzl¹⁰, R. Plačakytė¹⁰, B. Pokorny²⁵, R. Polifka²⁵^,39, V. Radescu⁴⁵, N. Raicevic²³, T. Ravdandorj²⁸, P. Reimer²⁴, E. Rizvi¹⁵, P. Robmann³⁴, R. Roosen³, A. Rostovtsev⁴², M. Rotaru⁴, S. Rusakov¹⁹, D. Šálek²⁵, D. P. C. Sankey⁵, M. Sauter¹², E. Sauvan¹⁶^,40, S. Schmitt¹⁰^*, L. Schoeffel⁹, A. Schöning¹², F. Sefkow¹⁰, S. Shushkevich³⁶, Y. Soloviev¹⁰^,19, P. Sopicki⁶, D. South¹⁰, V. Spaskov⁸, A. Specka²², M. Steder¹⁰, B. Stella²⁶, U. Straumann³⁴, T. Sykora³^,25, P. D. Thompson², D. Traynor¹⁵, P. Truöl³⁴, I. Tsakov²⁷, B. Tseepeldorj²⁸^,38, J. Turnau⁶, A. Valkárová²⁵, C. Vallée¹⁶, P. Van Mechelen³, Y. Vazdik¹⁹, D. Wegener⁷, E. Wünsch¹⁰, J. Žáček²⁵, Z. Zhang²¹, R. Žlebčík²⁵, H. Zohrabyan³¹ and F. Zomer²¹

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 Rutherford Appleton Laboratory, STFC, Didcot, Oxfordshire, UK
⁶ Institute of Nuclear Physics, Polish Academy of Sciences, 31342, Krakow, 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 Cedex, 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, Rom, 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, 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, Toronto, ON, M5S 1A7, 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 Now at Nuclear Physics Institute of the CAS, Řež, Czech Republic
⁴⁵ Now at Department of Physics, Oxford University, Oxford, UK

^* e-mail: sschmitt@mail.desy.de

Received: 18 March 2016
Accepted: 12 June 2016
Published online: 7 July 2016

Abstract

Signals of QCD instanton-induced processes are searched for in neutral current deep-inelastic scattering at the electron-proton collider HERA in the kinematic region defined by the Bjorken-scaling variable , the inelasticity and the photon virtuality GeV. The search is performed using H1 data corresponding to an integrated luminosity of 351 pb. No evidence for the production of QCD instanton-induced events is observed. Upper limits on the cross section for instanton-induced processes between 1.5 and 6 pb, at confidence level, are obtained depending on the kinematic domain in which instantons could be produced. Compared to earlier publications, the limits are improved by an order of magnitude and for the first time are challenging predictions.