Observation and differential cross section measurement of neutral
current DIS events with an empty hemisphere in the Breit frame
The H collaboration,V. Andreev,M. Arratia,A. Baghdasaryan,A. Baty,K. Begzsuren,A. Bolz,V. Boudry,G. Brandt,D. Britzger,A. Buniatyan,L. Bystritskaya,A. J. Campbell,K. B. Cantun Avila,K. Cerny,V. Chekelian,Z. Chen,J. G. Contreras,J. Cvach,J. B. Dainton,K. Daum,A. Deshpande,C. Diaconu,A. Drees,G. Eckerlin,S. Egli,E. Elsen,L. Favart,A. Fedotov,J. Feltesse,M. Fleischer,A. Fomenko,C. Gal,J. Gayler,L. Goerlich,N. Gogitidze,M. Gouzevitch,C. Grab,T. Greenshaw,G. Grindhammer,D. Haidt,R. C. W. Henderson,J. Hessler,J. Hladký,D. Hoffmann,R. Horisberger,T. Hreus,F. Huber,P. M. Jacobs,M. Jacquet,T. Janssen,A. W. Jung,J. Katzy,C. Kiesling,M. Klein,C. Kleinwort,H. T. Klest,S. Kluth,R. Kogler,P. Kostka,J. Kretzschmar,D. Krücker,K. Krüger,M. P. J. Landon,W. Lange,P. Laycock,S. H. Lee,S. Levonian,W. Li,J. Lin,K. Lipka,B. List,J. List,B. Lobodzinski,O. R. Long,E. Malinovski,H. -U. Martyn,S. J. Maxfield,A. Mehta,A. B. Meyer,J. Meyer,S. Mikocki,V. M. Mikuni,M. M. Mondal,K. Müller,B. Nachman,Th. Naumann,P. R. Newman,C. Niebuhr,G. Nowak,J. E. Olsson,D. Ozerov,S. Park,C. Pascaud,G. D. Patel,E. Perez,A. Petrukhin,I. Picuric,D. Pitzl,R. Polifka,S. Preins,V. Radescu,N. Raicevic,T. Ravdandorj,D. Reichelt,P. Reimer,E. Rizvi,P. Robmann,R. Roosen,A. Rostovtsev,M. Rotaru,D. P. C. Sankey,M. Sauter,E. Sauvan,S. Schmitt,B. A. Schmookler,G. Schnell,L. Schoeffel,A. Schöning,S. Schumann,F. Sefkow,S. Shushkevich,Y. Soloviev,P. Sopicki,D. South,A. Specka,M. Steder,B. Stella,L. Stöcker,U. Straumann,C. Sun,T. Sykora,P. D. Thompson,F. Torales Acosta,D. Traynor,B. Tseepeldorj,Z. Tu,G. Tustin,A. Valkárová,C. Vallée,P. Van Mechelen,D. Wegener,E. Wünsch,J. Žáček,J. Zhang,Z. Zhang,R. Žlebčík,H. Zohrabyan,F. Zomer
arxiv（2024）
引用0|浏览6
暂无评分
摘要
The Breit frame provides a natural frame to analyze lepton-proton scattering
events. In this reference frame, the parton model hard interactions between a
quark and an exchanged boson defines the coordinate system such that the struck
quark is back-scattered along the virtual photon momentum direction. In Quantum
Chromodynamics (QCD), higher order perturbative or non-perturbative effects can
change this picture drastically. As Bjorken-x decreases below one half, a
rather peculiar event signature is predicted with increasing probability, where
no radiation is present in one of the two Breit-frame hemispheres and all
emissions are to be found in the other hemisphere. At higher orders in
α_s or in the presence of soft QCD effects, predictions of the rate of
these events are far from trivial, and that motivates measurements with real
data. We report on the first observation of the empty current hemisphere events
in electron-proton collisions at the HERA collider using data recorded with the
H1 detector at a center-of-mass energy of 319 GeV. The fraction of inclusive
neutral-current DIS events with an empty hemisphere is found to be 0.0112 ±
3.9 %_stat± 4.5 %_syst± 1.6 %_mod in the
selected kinematic region of 150< Q^2<1500 GeV^2 and inelasticity 0.14<
y<0.7. The data sample corresponds to an integrated luminosity of 351.1
pb^-1, sufficient to enable differential cross section measurements of
these events. The results show an enhanced discriminating power at lower
Bjorken-x among different Monte Carlo event generator predictions.
