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

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

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

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

Measurement of the proton structure function F2 (x, Q2) in the low-x region at HERA

A measurement of the proton structure function F2 (x, Q2) is presented with about 1000 neutral current deep inelastic scattering events for Bjorken x in the range x {reversed tilde equals} 10-2 - 10-4 and Q2 > 5 GeV2. The measurement is based on an integrated luminosity of 22.5 nb-1 recorded by the H1 detector in the first year of HERA operation. The structure function F2 (x, Q2) shows a significant rise with decreasing x. © 1993.0320 auteursSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Inclusive charged particle cross-sections in photoproduction at HERA

Cross sections are presented for the inclusive production of charged particles measured in electron-proton collisions at low Q 2 with the H1 detector at HERA. The transverse momentum distribution extends up to 8 GeV/ c . Its shape is found to be harder than that observed in p p collisions at comparable centre-of-mass energies √S γp ≈ √S p p ≈ 200 GeV , and also harder than in γp collisions at lower energies √ S γp ≈ 18 GeV. Results from quantum chromodynamics (QCD) calculations agree with the measured transverse momentum and pseudorapidity cross sections

The Gluon density of the proton at low x from a QCD analysis of F2

We present a QCD analysis of the proton structure function $F_2$ measured by the H1 experiment at HERA, combined with data from previous fixed target experiments. The gluon density is extracted from the scaling violations of $F_2$ in the range $2\cdot 10^{-4}<x<3\cdot 10^{-2}$ and compared with an approximate solution of the QCD evolution equations. The gluon density is found to rise steeply with decreasing $x$.Comment: 17 pages, latex2e, 5 figures appended as uuencoded file, hep number include

A Study of the fragmentation of quarks in e- p collisions at HERA

Deep inelastic scattering (DIS) events, selected from 1993 data taken by the H1 experiment at HERA, are studied in the Breit frame of reference. The fragmentation function of the quark is compared with those of \ee data. It is shown that certain aspects of the quarks emerging from within the proton in \ep interactions are essentially the same as those of quarks pair-created from the vacuum in \ee annihilation. The measured area, peak position and widthof the fragmentation function show that the kinematic evolution variable, equivalent to the \ee squared centre of mass energy, is in the Breit frame the invariant square of the four-momentum transfer. We comment on the extent to which we have evidence for coherence effects in parton showers.Comment: 18 pages, latex, 7 figures appended as uuencoded fil

First measurement of the deep-inelastic structure of proton diffraction

A measurement is presented, using data taken with the H1 detector at HERA, of the contribution of diffractive interactions to deep-inelastic electron-proton scattering. The diffractive contribution to the proton structure function is evaluated as a function of the appropriate deep-inelastic scattering variables using a class of deep-inelastic ep scattering events with no hadronic energy flow in an interval of pseudo-rapidity adjacent to the proton beam direction. The dependence of this contribution on x-pomeron is consistent with both a diffractive interpretation and a factorisable ep diffractive cross section. A first measurement of the deep-inelastic structure of the pomeron in the form of a factorised structure function is presented. This structure function is observed to be consistent with scale invariance