Search for Events with Isolated Leptons and Large Missing Transverse Momentum

Events with isolated leptons and large missing transverse momentum are searched for in the e+p and e−p data recorded by the H1 experiment at HERA. In previous analyses of the HERA I e+p data (L = 104.7 pb−1), an excess of events with isolated electrons or muons and large missing transverse momentum was found. No significant excess was found in the HERA I e−p data (L = 13.6 pb−1). In the following, new results of the search for events with isolated leptons and large missing transverse momentum in the HERA II e+p and e−p datasets are presented. The analysed HERA II data correspond to integrated luminosities of 53 pb−1 and 21 pb−1 in e+p and e−p collisions, respectively.

[1]  John David Jackson,et al.  Classical Electrodynamics , 2020, Nature.

[2]  J. G. Contreras,et al.  Search for bosonic stop decays in R-parity violating supersymmetry in e^+p collisions at HERA. , 2004 .

[3]  C. Issever,et al.  An improved weighting algorithm to achieve software compensation in a fine grained LAr calorimeter , 2004, physics/0408129.

[4]  J. Cvach.  Evidence for a narrow anti-charmed baryon state , 2004 .

[5]  The H1 Collaboration.  Search for squark production in R-parity violating supersymmetry at HERA , 2004, hep-ex/0403027.

[6]  J. G. Contreras,et al.  Muon pair production in ep collisions at HERA , 2004 .

[7]  C. Dionisi,et al.  Measurement of Triple-Gauge-Boson Couplings of the W Boson at LEP , 2004, hep-ex/0402036.

[8]  K. Piotrzkowski,et al.  Isolated tau leptons in events with large missing transverse momentum at HERA , 2003, hep-ex/0311028.

[9]  The H1 Collaboration.  Search for single top quark production in ep collisions at HERA , 2003, hep-ex/0310032.

[10]  The H1 Collaboration.  Multi-electron production at high transverse momenta in ep collisions at HERA , 2003, hep-ex/0307015.

[11]  E. Barrelet,et al.  Isolated electrons and muons in events with missing transverse momentum at HERA , 2003 .

[12]  Jürgen Naumann,et al.  Entwicklung und Test der dritten H1-Triggerstufe , 2003 .

[13]  Christoph Wissing,et al.  Entwicklung eines Simulationsprogramms und Implementierung schneller Spurfitalgorithmen für den neuen H1-Driftkammertrigger , 2003 .

[14]  T. Carli,et al.  A multi-variate discrimination technique based on range-searching , 2002, hep-ex/0211019.

[15]  L3 Collaboration.  Search for single top production at LEP , 2002, Physics Letters B.

[16]  C. Schwanenberger,et al.  Photoproduction of W bosons at HERA: QCD corrections , 2002, hep-ph/0203269.

[17]  T. Abe.  GRAPE-Dilepton (version1.1), A Generator for Dilepton Production in ep Collisions , 2000, hep-ph/0012029.

[18]  C. Wissing,et al.  A fast high resolution track trigger for the H1 experiment , 2000, 2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149).

[19]  J. Dainton.  Photon structure and quantum fluctuation , 2000, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[20]  R. Nahnhauer,et al.  The H1 forward proton spectrometer at HERA , 2000, hep-ex/0001046.

[21]  R. Engel,et al.  Color singlet exchange between jets and the PHOJET Monte Carlo , 1999 .

[22]  T. Junk,et al.  Confidence Level Computation for Combining Searches with Small Statistics , 1999, hep-ex/9902006.

[23]  H. Fritzsch,et al.  The production of single t-quarks at LEP and HERA , 1999, hep-ph/9901411.

[24]  Fons Rademakers,et al.  ROOT — An object oriented data analysis framework , 1997 .

[25]  Raúl Rojas,et al.  Neural Networks - A Systematic Introduction , 1996 .

[26]  E. Barrelet,et al.  Performance of an electromagnetic lead/scintillating-fibre calorimeter for the H1 detector , 1996 .

[27]  Tetsuro Kobayashi,et al.  Is a high PT muon of the e+p → μ+X event observed at HERA a signature of the stop? , 1996, hep-ph/9601338.

[28]  M. Peskin,et al.  An Introduction To Quantum Field Theory , 1995 .

[29]  Hannes Jung,et al.  Hard diffractive scattering in high energy ep collisions and the Monte Carlo Generator RAPGAP , 1995 .

[30]  Joshua R. Smith,et al.  Observation of an e+ p ---> mu+ X event with high transverse momenta at HERA , 1994 .

[31]  T. Sjöstrand.  High-energy-physics event generation with PYTHIA 5.7 and JETSET 7.4 , 1994 .

[32]  H. Kolanoski,et al.  Electron / pion separation with the H1 LAr calorimeters , 1994 .

[33]  E. Vogel,et al.  Results from pion calibration runs for the H 1 liquid argon calorimeter and comparisons with simulations , 1993 .

[34]  M. Seymour,et al.  Longitudinally-invariant k ⊥ -clustering algorithms for hadron-hadron collisions , 1993 .

[35]  Ellis,et al.  Successive combination jet algorithm for hadron collisions. , 1993, Physical review. D, Particles and fields.

[36]  Alan D. Martin,et al.  Tau polarization and its correlations as a probe of new physics , 1993 .

[37]  L. Lönnblad.  Ariadne version 4 — A program for simulation of QDC cascades implementing the colour dipole model , 1992 .

[38]  U. Baur,et al.  Electroweak vector boson production in high-energy ep collisions , 1992 .

[39]  M. Kuhlen.  The fast H1 detector Monte Carlo , 1992 .

[40]  S. Maxfield,et al.  Precision reconstruction of charged tracks with simultaneous electron identification in a gaseous detector using transition radiation , 1991 .

[41]  C. Carimalo,et al.  High-pT lepton pair production at ep colliders: comparison between various production mechanisms , 1991 .

[42]  Carlo E. Vandoni,et al.  PAW, a general-purpose portable software tool for data analysis and presentation , 1989 .

[43]  S. Maxfield,et al.  Radial wire drift chambers for the H1 forward track detector at HERA: design, construction and performance , 1989 .

[44]  P. Waloschek,et al.  The Central jet chamber of the H1 experiment , 1989 .

[45]  W. Buchmüller,et al.  Leptoquarks in lepton-quark collisions , 1987 .

[46]  G. Gustafson.  Dual description of a confined colour field , 1986 .

[47]  S. Komamiya,et al.  Excited lepton production at LEP and HERA , 1985 .

[48]  J. Vermaseren.  Two Photon Processes at Very High-Energies , 1983 .

[49]  J. Hammersley.  SIMULATION AND THE MONTE CARLO METHOD , 1982 .

[50]  S. Wolfram,et al.  A model for parton showers in QCD , 1980 .

[51]  G. Parisi,et al.  Asymptotic Freedom in Parton Language , 1977 .

[52]  D. Perkins.  Introduction to high energy physics , 1973 .

[53]  J. J. Sakurai,et al.  Generalized vector dominance and inelastic electron - proton scattering , 1972 .

[54]  S. Glashow,et al.  Weak Interactions with Lepton-Hadron Symmetry , 1970 .

[55]  Richard E. Taylor,et al.  OBSERVED BEHAVIOR OF HIGHLY INELASTIC ELECTRON-PROTON SCATTERING , 1969 .

[56]  D. Gross,et al.  High-energy electroproduction and the constitution of the electric current , 1969 .

[57]  J. J. Sakurai.  Theory of strong interactions , 1960 .

[58]  P. A. Čerenkov.  Visible radiation produced by electrons moving in a medium with velocities exceeding that of light , 1937 .

[59]  W. Heitler,et al.  On the Stopping of Fast Particles and on the Creation of Positive Electrons , 1934 .

[60]  E. J. Williams.  Nature of the high-energy particles of penetrating radiation and status of ionization and radiation formulae , 1934 .

[61]  O. Henshaw.  A First Measurement of the Neutral Current Cross Section at High $Q^2$ in Longitudinally Polarised $e^+p$ Scattering with the H1 Detector , 2005 .

[62]  Running at Low Proton Beam Energies , 2005 .

[63]  E. Woehrling.  High $Q^2$ Neutral Current interactions at H1 and an extraction of $x \tilde{F}_3$ , 2004 .

[64]  K. Meier,et al.  Search for Squark Production in R-Parity Violating Supersymmetry at HERA , 2004 .

[65]  D. Bailey,et al.  Search for single-top production in e p collisions at HERA , 2003 .

[66]  Y. H. Fleming.  The H1 First Level Fast Track Trigger , 2003 .

[67]  D. Dannheim.  Search for events with isolated leptons and large missing transverse momentum in e p collisions at HERA , 2003 .

[68]  J. Dingfelder.  Search for Anomalous Production of Single Top Quarks with the H1 Experiment at HERA , 2003 .

[69]  C. Berger,et al.  Muon pair production in electron-proton collisions , 2002 .

[70]  Jürgen Rauschenberger.  Prozesse des geladenen Stromes in tiefunelastischer Positron-Proton Streuung bei HERA , 2002 .

[71]  G. Hoffstaetter.  The luminosity upgrade of HERA , 2001 .

[72]  Shigeo Abe DrEng.  Pattern Classification , 2001, Springer London.

[73]  S. Moretti,et al.  HERWIG 6: an event generator for hadron emission reactions with interfering gluons (including supersymmetric processes) , 2001 .

[74]  N. Malden.  W production in e p collisions , 2000 .

[75]  M. Spira,et al.  A Note on W Boson Production at HERA , 1999 .

[76]  Philippe Bruel,et al.  Recherche d'interactions au-dela du modele standard a hera , 1998 .

[77]  U. Langenegger.  A measurement of the beauty and charm production cross sections at the ep collider HERA , 1998 .

[78]  Volker Blobel,et al.  Statistische und numerische Methoden der Datenanalyse , 1998 .

[79]  Shapiro,et al.  Search for Flavor-Changing Neutral Current Decays of the Top Quark in p{bar p} Collisions at â({ital s}) =1.8 TeV , 1998 .

[80]  J. Ryan,et al.  Cross Sections in Photoproduction at HERA ZEUS Collaboration , 1998 .

[81]  William J. Thompson,et al.  Atlas for Computing Mathematical Functions: An Illustrated Guide for Practitioners with Programs in Fortran 90 and Mathematica , 1997 .

[82]  Andreas Zell,et al.  Simulation neuronaler Netze , 1994 .

[83]  D. Griffiths.  Introduction to Elementary Particles , 1987 .

[84]  Konrad Kleinknecht,et al.  Detektoren für Teilchenstrahlung , 1987 .

[85]  Y. Dokshitzer,et al.  Calculation of the Structure Functions for Deep Inelastic Scattering and e+ e- Annihilation by Perturbation Theory in Quantum Chromodynamics. , 1977 .

[86]  G. Altarelli,et al.  Deep inelastic processes in ladder models. , 1973 .

[87]  V. Gribov,et al.  e$sup +$e$sup -$-PAIR ANNIHILATION AND DEEP INELASTIC ep-SCATTERING IN PERTURBATION THEORY. , 1972 .

[88]  R. Feynman.  Photon-hadron Interactions , 1972 .

[89]  D. J.,et al.  Inelastic Electron-Proton and ~-Proton Scattering and the Structure of the Nucleon * , 2022 .