Search for QCD instanton-induced processes in deep-inelastic scattering at HERA

Summary, in English

Signals of QCD instanton-induced processes are searched for in deep-inelastic scattering (DIS) at the electron-proton collider HERA in a kinematic region defined by the Bjorken-scaling variables x > 10(-3), 0.1 < y < 0.6 and photon virtualities 10 less than or similar to Q(2) < 100 GeV2. Several observables characterising hadronic final state properties of QCD instanton-induced events are exploited to identify a potentially instanton-enriched domain. While an excess of events with instanton-like topology is observed it cannot be claimed significant given the uncertainty of the standard DIS background simulation. Upper limits on the cross-section for instanton-induced processes of between 60 pb and 1000 pb are set dependent on the kinematic domain considered. The data do not exclude the cross-section predicted by instanton perturbation theory for small instanton sizes. At large instanton sizes a naive extrapolation of instanton perturbation theory yields a cross-section in the range of sensitivity of this study. Such a cross-section is not observed, in agreement with non-perturbative lattice simulations of the QCD vacuum.

• Author: C Adloff; V Andreev; B Andrieu; T Anthonis; A Astvatsatourov; A Babaev; J Bahr; P Baranov; E Barrelet; W Bartel; J Becker; M Beckingham; A Beglarian; O Behnke; C Beier; A Belousov; C Berger; T Berndt; JC Bizot; J Bohme; V Boudry; W Braunschweig; V Brisson; HB Broker; DP Brown; D Bruncko; FW Busser; A Bunyatyan; A Burrage; G Buschhorn; L Bystritskaya; AJ Campbell; T Carli; S Caron; F Cassol-Brunner; D Clarke; C Collard; JG Contreras; YR Coppens; JA Coughlan; MC Cousinou; BE Cox; G Cozzika; J Cvach; JB Dainton; WD Dau; K Daum; Mattias Davidsson; B Delcourt; N Delerue; R Demirchyan; A De Roeck; EA De Wolf; C Diaconu; J Dingfelder; P Dixon; V Dodonov; JD Dowell; A Droutskoi; A Dubak; C Duprel; G Eckerlin; D Eckstein; V Efremenko; S Egli; R Eichler; F Eisele; E Eisenhandler; M Ellerbrock; E Elsen; M Erdmann; W Erdmann; PJW Faulkner; L Favart; A Fedotov; R Felst; J Ferencei; S Ferron; M Fleischer; P Fleischmann; YH Fleming; G Flugge; A Fomenko; I Foresti; J Formanek; G Franke; G Frising; E Gabathuler; K Gabathuler; J Garvey; J Gassner; J Gayler; R Gerhards; C Gerlich; S Ghazaryan; L Goerlich; N Gogitidze; C Grab; V Grabski; H Grassler; T Greenshaw; G Grindhammer; T Hadig; D Haidt; L Hajduk; L Haller; WJ Haynes; B Heinemann; G Heinzelmann; RCW Henderson; S Hengstmann; H Henschel; R Heremans; G Herrera; I Herynek; M Hildebrandt; M Hilgers; KH Hiller; J Hladky; P Hoting; D Hoffmann; R Horisberger; A Hovhannisyan; S Hurling; M Ibbotson; C Issever; M Jacquet; M Jaffre; L Janauschek; X Janssen; V Jemanov; Leif Jönsson; C Johnson; DP Johnson; MAS Jones; Hannes Jung; D Kant; M Kapichine; Martin Karlsson; O Karschnick; F Keil; N Keller; J Kennedy; IR Kenyon; S Kermiche; C Kiesling; Pär Kjellberg; M Klein; C Kleinwort; T Kluge; G Knies; B Koblitz; SD Kolya; V Korbel; P Kostka; SK Kotelnikov; R Koutouev; T Lastovicka; P Laycock; E Lebailly; A Lebedev; B Leissner; R Lemrani; V Lendermann; S Levonian; Magnus Lindström; B List; E Lobodzinska; B Lobodzinski; A Loginov; N Loktionova; V Lubimov; S Luders; D Luke; L Lytkin; N Malden; E Malinovski; I Malinovski; S Mangano; R Maracek; P Marage; J Marks; R Marshall; HU Martyn; J Martyniak; SJ Maxfield; D Meer; A Mehta; K Meier; AB Meyer; H Meyer; J Meyer; PO Meyer; S Mikocki; D Milstead; S Mohrdieck; MN Mondragon; F Moreau; A Morozov; JV Morris; K Muller; P Murin; V Nagovizin; B Naroska; J Naumann; T Naumann; G Nellen; PR Newman; F Niebergall; C Niebuhr; O Nix; G Nowak; JE Olsson; D Ozerov; V Panassik; C Pascaud; GD Patel; M Peez; E Perez; A Petrukhin; JP Phillips; D Pitzl; R Poschl; I Potachnikova; B Povh; G Radel; J Rauschenberger; P Reimer; B Reisert; D Reyna; C Risler; E Rizvi; P Robmann; R Roosen; A Rostovtsev; S Rusakov; K Rybicki; DPC Sankey; S Schatzel; J Scheins; FP Schilling; P Schleper; D Schmidt; D Schmidt; S Schmidt; S Schmidt; M Schneider; L Schoeffel; A Schoning; T Schorner; V Schroder; HC Schultz-Coulon; C Schwanenberger; K Sedlak; F Sefkow; V Shekelyan; I Sheviakov; LN Shtarkov; Y Sirois; T Sloan; P Smirnov; Y Soloviev; D South; V Spaskov; A Specka; H Spitzer; R Stamen; B Stella; J Stiewe; I Strauch; U Straumann; M Swart; S Tchetchelnitski; G Thompson; PD Thompson; N Tobien; F Tomasz; D Traynor; P Truol; G Tsipolitis; I Tsurin; J Turnau; JE Turney; E Tzamariudaki; S Udluft; A Uraev; M Urban; A Usik; S Valkar; A Valkarova; C Vallee; P Van Mechelen; S Vassiliev; Y Vazdik; A Vest; A Vichnevski; K Wacker; J Wagner; R Wallny; B Waugh; G Weber; D Wegener; C Werner; N Werner; M Wessels; G White; S Wiesand; T Wilksen; M Winde; GG Winter; C Wissing; M Wobisch; EE Woehrling; E Wunsch; AC Wyatt; J Zacek; J Zalesak; Z Zhang; A Zhokin; F Zomer; M zur Nedden
• Department/s: Particle and nuclear physics; Chemical Physics
• Publishing year: 2002
• Language: English
• Pages: 495-509
• Publication/Series: European Physical Journal C. Particles and Fields
• Volume: 25
• Issue: 4
• Links: http://dx.doi.org/10.1140/epjc/s2002-01039-8
• Document type: Journal article
• Publisher: Springer
• Topic: Subatomic Physics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1434-6044