4-11 July 2012
Melbourne Convention and Exhibition Centre
Australia/Melbourne timezone
ICHEP2012 - 36th International Conference for High Energy Physics

Measurement and QCD Analysis Deep-Inelastic Scattering at HERA.

5 Jul 2012, 09:00
Room 219 (Melbourne Convention and Exhibition Centre)

Room 219

Melbourne Convention and Exhibition Centre

Melbourne Australia
Parallel Sessions Track 6. QCD, Jets, Parton Distributions TR 6 - RM 217 - QCD, Jets, Parton Distributions


Mr Zhiqing Philippe Zhang (Laboratoire de l'Accélérateur Linéaire (FR))


The inclusive e±p single and double differential cross sections for neutral and charged current processes are measured with the H1 detector at HERA. The data were taken at a centre-of-mass energy of √s = 319 GeV with a total integrated luminosity of 329.1 pb−1 shared between two lepton beam charges and two longitudinal lepton polarisation modes. The differential cross sections are measured in the range of four-momentum transfer squared, Q2 , between 120 and 50 000 GeV2 , and Bjorken x between 0.008 and 0.65. The measurements are combined with earlier published H1 data to determine the structure function xF_3^γ Z. A measurement of the neutral current parity violating structure function F_2^γ Z is presented for the first time. The polarisation dependence of the CC total cross section for Q2 > 400 GeV2 is found to be consistent with the Standard Model. The new measurements are well described by a next-to-leading order QCD fit using all published H1 inclusive cross section data which is used to extract flavour separated parton densities. A measurement is presented of the inclusive neutral current e±p scattering cross section using data collected by the H1 experiment at HERA during the years 2003 to 2007 with proton beam energies Ep of 920, 575, and 460 GeV. The kinematic range of the measurement covers low absolute four-momentum transfers squared, 1.5 GeV2 < Q2 < 120 GeV2, small values of Bjorken x, 2.9 • 10−5 < x < 0.01, and extends to high inelasticity up to y = 0.85. The structure function FL is measured by combining the new results with previously published H1 data at Ep = 920 GeV and Ep = 820 GeV. The new measurements are used to test several phenomenological and QCD models applicable in this low Q2 and low x kinematic domain. A precise knowledge of the integrated luminosity of the HERA collider is relevant for various types of cross section measurements and for a precise determination of the parton density functions of the proton. At ep colliders, the integrated luminosity is often measured in the Bethe Heitler process, using dedicated detectors located at small angles. In this paper, an alternative measurement of the integrated luminosity is presented, exploiting the elastic QED Compton process ep -> e gamma p. Both the electron and the photon are detected in the H1 backward calorimeter. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a relative precision of +-0.85%(stat) +-2.12%(sys), where (stat) is the statistical uncertainty and (sys) is the total systematic uncertainty. The measurement is found to be compatible with the corresponding Bethe-Heitler analysis.

Primary author

Mr Zhiqing Philippe Zhang (Laboratoire de l'Accélérateur Linéaire (FR))

Presentation materials