A Search for Selectrons and Squarks at HERA

Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure

A Measurement of the Proton Structure Function F ⁣2(x,Q2)F_{\!2}(x,Q^2)

A measurement of the proton structure function $F_{\!2}(x,Q^2)$ is reported for momentum transfer squared $Q^2$ between 4.5 $GeV^2$ and 1600 $GeV^2$ and for Bjorken $x$ between $1.8\cdot10^{-4}$ and 0.13 using data collected by the HERA experiment H1 in 1993. It is observed that $F_{\!2}$ increases significantly with decreasing $x$, confirming our previous measurement made with one tenth of the data available in this analysis. The $Q^2$ dependence is approximately logarithmic over the full kinematic range covered. The subsample of deep inelastic events with a large pseudo-rapidity gap in the hadronic energy flow close to the proton remnant is used to measure the "diffractive" contribution to $F_{\!2}$.Comment: 32 pages, ps, appended as compressed, uuencoded fil

Data Storage and Data Access at H1

Introduction At the electron proton collider HERA at the DESY laboratory in Hamburg, electrons of 27.6 GeV momentum are collided with 820GeV protons at a bunch crossing rate of 10.41 MHz, delivering (design) luminosities of 1:5 \Theta 10 31 cm \Gamma2 s \Gamma1 (peak luminosity) and 50pb \Gamma1 y \Gamma1 (integrated luminosity). The luminosity values reached up to now are 5:0 \Theta 10 30 cm \Gamma2 s \Gamma1 and 5pb \Gamma1 y \Gamma1 , respectively. The large bunch crossing rate poses particularly challenging requirements on the triggering and data acquisition facilities of the experiments. Cross sections for various physics processes at HERA and the resulting data rates are presented in table 1, assuming an

Computing at H1 - Experience and Future

Introduction At the electron proton collider Hera at the Desy laboratory in Hamburg, positrons of 27.6 GeV momentum are collided with 820 GeV protons. A schematic view of the H1 detector 1 -- one of the four big experiments operated at Hera -- is shown in figure 1. The bunch crossing rate at Hera is 10.41 MHz giving a bunch separation of 96 ns. The H1 experiment is taking data at a logging rate of about 10Hz or about 500 KB/s on average, resulting in a yearly raw data volume of about 5 TB. Data is reconstructed quasi-online, yielding another 5 TB of reconstructed data after physics oriented event classification. Raw and reconstructed data are kept on tape only. Part of the reconstructed event information is kept on disk in form of DST data. After software compression, the DST data amounts to about 300GB 2;3 . These data volumes are a new challenge for experiments at HERA, even if thes

Measurement of the e+ and e- induced charged current cross-sections at HERA

The cross sections for the charged current processes ${e^{-}p}\rightarrow{\nu_e+hadrons}$ and, for the first time, ${e^{+}p}\rightarrow{\overline{\nu}_e+hadrons}$ are measured at HERA for transverse momenta larger than 25 GeV.Comment: 21 pages, latex, 10 figures appended as uuencoded fil

First measurement of the charged current cross-section at HERA

The cross section of the charged current process e − p → v e + hadrons is measured at HERA for transverse momenta of the hadron system larger than 25 GeV. The size of the cross section exhibits the W propagator

Deep inelastic scattering events with a large rapidity gap at HERA

Evidence is presented using data taken with the H1 detector at HERA for a class of deep inelastic electron-proton scattering (DIS) events (5 < Q2 < 120 GeV2) at low Bjorken-x (10-4 < x < 10-2) which have almost no hadronic energy flow in a large interval of pseudo-rapidity around the proton remnant direction and which cannot be attributed to our present understanding of DIS and fluctuations in final state hadronic fragmentation. From an integrated luminosity of 273 nb-1, 734 events, that is about 5% of the total DIS sample, have no energy deposition greater than 400 MeV forward of laboratory pseudo-rapidity ηmax = 1.8 up to the largest measurable pseudo-rapidity of about 3.65. Evidence that about 10% of observed rapidity gap events are exclusive vector meson electroproduction is presented. Good descriptions of the data are obtained using models based either on a vector meson dominance like picture, which includes a large fraction of inelastic virtual photon dissociation, or on deep inelastic electron-pomeron scattering in which the partonic sub-structure of the latter is resolved. © 1994.0400 auteursSCOPUS: ar.jinfo:eu-repo/semantics/publishe

A Search for heavy leptons at HERA

A search for direct production of new leptons in the mass range from 10 GeV up to 225 GeV is presented by the H1 experiment at HERA. The data were obtained during 1993 and correspond to an integrated luminosity of 528 nb-1. The search includes heavy lepton decays to final states e (ν) γ and e (ν) W, e(ν) Z with the subsequent decay of the W and Z bosons into jets or lepton pairs. No evidence was found for the production of new massive electrons or neutrinos in any of the decay channels. Rejection limits for excited electrons and neutrinos are derived. © 1994.0400 auteursSCOPUS: ar.jinfo:eu-repo/semantics/publishe