A characteristic plot of pomeron-exchanged processes in diffractive DIS

The dependence of the fractal behaviors of the pomeron induced system in deep inelastic lepton-nucleon scattering upon the diffractive kinematic variables is found rather robust and not sensitive to the distinct parameterization of the pomeron flux factor and structure function. A feasible experimental test of the phenomenological pomeron-exchanged model based on the fractal measurement in DESY $ep$ collider HERA is proposed.Comment: 14 pages, 2 Postscript figure

High Q2Q^2 Physics at HERA and Searches for New Particles

Preliminary results from H1 and ZEUS on Deep Inelastic Scattering (DIS) at high momentum transfer squared $Q^2$ are presented. Used are all available $e^+ p$ data accumulated by the H1 and ZEUS experiments between 1994 and 1997, corresponding to integrated luminosities of $37 {pb}^{-1}$ and $47 {pb}^{-1}$, respectively. The anomalies observed at high $Q^2$ in the 1994 to 1996 data still remain, though with less significance. Since this high $Q^2$ domain represents a new frontier in DIS, the same data are used to search for new particles possessing direct couplings to lepton-quark pairs. Assuming that the slight excess of events observed in Neutral Current DIS is due to a statistical fluctuation, preliminary limits on the production of leptoquarks and of squarks in R-parity violating MSSM are presented.Comment: 14 pages, 12 figures, uses iopart style files, contribution to the 3rd UK Phenomenology Workshop on HERA Physics, Durham, Sep 199

Soft Photoproduction Physics

Several topics of interest in soft photoproduction physics are discussed. These include jet universality issues (particle flavour composition), the subdivision into event classes, the buildup of the total photoproduction cross section and the effects of multiple interactions.Comment: 10 pages, LaTeX2e, no figures, to appear in the proceedings of the Durham Workshop on HERA Physics, ``Proton, Photon and Pomeron Structure'', 17--23 September 1995, Durham, U.

A Unified Treatment of High Energy Interactions

It is well known that high energy interactions as different as electron-positron annihilation, deep inelastic lepton-nucleon scattering, proton-proton interactions, and nucleus-nucleus collisions have many features in common. Based upon this observation, we construct a model for all these interactions, which relies on the fundamental hypothesis that the behavior of high energy interactions is universal.Comment: 4 pages, LaTeX created with LyX, 8 figures, more figures at http://www-subatech.in2p3.fr/~theo/nexus/example

Deep inelastic J/ψJ/\psi production at HERA in the kTk_T-factorization approach and its consequences for the nonrelativistic QCD

In the framework of the $k_T$-factorization approach, we analyse the inclusive and inelastic production of $J/\psi$ particles in deep inelastic $ep$ scattering. We take into account both colour-singlet and colour-octet production channels. We inspect the sensitivity of theoretical predictions to the choice of model parameters. Our theoretical results agree reasonably well with recent experimental data collected by the collaboration H1 at HERA.Comment: 14 pages, 6 figure

Working Group Report on the Structure of the Proton

We summarize the developments on the structure of the proton that were studied at the Workshop on "HERA Physics" that was held in Durham in September 1995. We survey the latest structure function data; we overview the QCD interpretations of the measurements of the structure functions and of final state processes; we discuss charm production and the spin properties of the proton.Comment: 45 pages, latex file using epsfig and ioplppt macros. Figures included, but full resolution figure files and postscript file of the whole paper are available via anonymous ftp at ftp://cpt1.dur.ac.uk/pub/preprints/dtp96/dtp962

Jets and energy flow in photon-proton collisions at HERA

Properties of the hadronic final state in photoproduction events with large transverse energy are studied at the electron-proton collider HERA. Distributions of the transverse energy, jets and underlying event energy are compared to \overline{p}p data and QCD calculations. The comparisons show that the \gamma p events can be consistently described by QCD models including -- in addition to the primary hard scattering process -- interactions between the two beam remnants. The differential jet cross sections d\sigma/dE_T^{jet} and d\sigma/d\eta^{jet} are measured

Разработка интерактивной моделирующей системы технологии низкотемпературной сепарации газа

We present a study of J ψ meson production in collisions of 26.7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The J ψ mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of σ(ep → J ψ X) = (8.8±2.0±2.2) nb is determined for 30 GeV ≤ W γp ≤ 180 GeV and Q 2 ≲ 4 GeV 2 . Using the flux of quasi-real photons with Q 2 ≲ 4 GeV 2 , a total production cross section of σ ( γp → J / ψX ) = (56±13±14) nb is derived at an average W γp =90 GeV. The distribution of the squared momentum transfer t from the proton to the J ψ can be fitted using an exponential exp(− b ∥ t ∥) below a ∥ t ∥ of 0.75 GeV 2 yielding a slope parameter of b = (4.7±1.9) GeV −2

Experimental Study of Hard Photon Radiation Processes at HERA

: We present an experimental study of the ep ! efl + p and ep ! efl + X processes using data recorded by the H1 detector in 1993 at the electron-proton collider HERA. These processes are employed to measure the luminosity with an accuracy of 4.5 %. A subsample of the ep ! efl + X events in which the hard photon is detected at angles ` 0 fl 0:45 mrad with respect to the incident electron direction is used to verify experimentally the size of radiative corrections to the ep ! eX inclusive cross section and to investigate the structure of the proton in the Q 2 domain down to 2 GeV 2 , lower than previously attained at HERA. Submitted to Zeitschrift fur Physik C H1 Collaboration T. Ahmed 3 , S. Aid 13 , V. Andreev 24 , B. Andrieu 28 , R.-D. Appuhn 11 , M. Arpagaus 36 , A. Babaev 26 , J. Baehr 35 , J. B'an 17 , P. Baranov 24 , E. Barrelet 29 , W. Bartel 11 , M. Barth 4 , U. Bassler 29 , H.P. Beck 37 , H.-J. Behrend 11 , A. Belousov 24 , Ch. Berger ..