Determination of the longitudinal structure function FLF_{L} at HERA

Recent results from the HERA experiment H1 on the longitudinal stucture function $F_{L}$ of the proton are presented. They include proton structure function analyses with particular emphasis on those kinematic regions which are sensitive to $F_{L}$. All results can be consistently described within the framework of perturbative QCD.Comment: 16 pages, 11 figures (requires iopart, iopams and epsfig); Talk presented in the Intern. Workshop on New Trends in HERA Physics 2001, 17-22 June 2001, Ringberg Castle, Tegernsee, Germany; To appear in the Proceeding

Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA

Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections sigma(c (c) over bar)(red) for charm production are obtained in the kinematic range of photon virtuality 2.5 LT = Q(2) LT = 2000 GeV2 and Bjorken scaling variable 3 . 10(-5) LT = x LT = 5 . 10(-2). The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W-+/- and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined

A search for leptoquarks, leptogluons and excited leptons in H1 at HERA

A direct search for new particles in the H1 experiment at HERA is presented for masses ranging from 35 GeV up to #propor to# 250 GeV. The data sample of 24 nb"-"1 accumulated during the first year of operation was analysed for signatures of scalar and vector leptoquarks, leptogluons, excited electrons and excited neutrinos with flavours of the first generation. No evidence for the production of such particles was found in various possible decay channels. Rejection limits are derived. (orig.)Available from TIB Hannover: RA 2999(93-029) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

A measurement of multi-jet rates in deep-inelastic scattering at HERA

Multi-jet production is observed in deep-inelastic electron proton scattering with the H1 detector at HERA. Jet rates for momentum transfers squared up to 500 GeV"2 are determined using the JADE jet clustering algorithm. They are found to be in agreement with predictions from QCD based models. (orig.)Available from TIB Hannover: RA 2999(93-137) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Measurement of the proton structure function F_2(x,Q"2) in the low x region at HERA

A measurement of the proton structure function F_2(x, Q"2) is presented with about 1000 neutral current deep inelastic scattering events for Bjorken x in the range x#approx =#10"-"2-10"-"4 and Q"2>5 GeV"2. 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 F_2(x, Q"2) shows a significant rise with decreasing x. (orig.)Available from TIB Hannover: RA 2999(93-117) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Energy flow and charged particle spectra in deep inelastic scattering at HERA

Global properties of the hadronic final state in deep inelastic scattering events at HERA are investigated. The data are corrected for detector effects and are compared directly with QCD phenomenology. Energy flows in both the laboratory frame and the hadronic centre of mass system and energy-energy correlations in the laboratory frame are presented. Comparing various QCD models, the colour dipole model provides the only satisfactory description of the data. In the hadronic centre of mass system the momentum components of charged particles longitudinal and transverse to the virtual boson direction are measured and compared with lower energy lepton-nucleon scattering data as well as with e"+e"- data from LEP. (orig.)Available from TIB Hannover: RA 2999(94-033) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Scaling violations of the proton structure function F_2 at small x

An analysis is presented of scaling violations of the proton structure function F_2(x, Q"2) measured with the H1 detector at HERA in the range of Bjorken x values between x=3 x 10"-"4 and 10"-"2 for four-momentum transfers Q"2 larger than 8.7 GeV"2. The structure function F_2(x, Q"2) is observed to rise linearly with lnQ"2. Under the assumption that the observed scaling violations at small x#<=#0.01 are described correctly by perturbative QCD, an estimate is obtained of the gluon distribution function G(x, Q_o"2) at Q_o"2=20 GeV"2. (orig.)Available from TIB Hannover: RA 2999(93-146) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The H1 detector at HERA

Technical aspects of the H1 detector at the electron-proton storage ring HERA are described. Some performance figures from the first luminosity phase of HERA are given, too. (orig.)SIGLEAvailable from TIB Hannover: RA 2999(93-103) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

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 anti pp collisions at comparable centre-of-mass energies #sq root#s_#gamma#_p#approx##sq root#s anti pp#approx#200 GeV, and also harder than in #gamma#p collisions at lower energies #sq root#s_#gamma#_p#approx#18 GeV. Results from quantum chromodynamics (QCD) calculations agree with the measured transverse momentum and pseudorapidity cross sections. (orig.)Available from TIB Hannover: RA 2999(94-030) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Measurement of inclusive jet cross sections in photoproduction at HERA

The inclusive jet cross section in photoproduction has been measured as a function of transverse energy and pseudorapidity using the H 1 detector at the HERA electron-proton collider. The results are compared with leading order QCD calculation