arXiv subjects

Zhiqing Zhang

Publications and source records attributed to Zhiqing Zhang.

45 records · Page 3Linked to original sources

arXiv2005

Physics from Polarized ep Collisions at HERA

Physics from the polarized electron or positron beam colliding with the unpolarized proton beam at HERA-II as well as from the unpolarized ep collisions at HERA-I is discussed. Results shown include (i) inclusive neutral and charged current cross sections and structure functions measurements at HERA-I, (ii) the impact of these measurements on parton density functions, on electroweak parameters and searches for new physics and (iii) the first results at HERA-II and its future prospects.

hep-ex↗

arXiv2004

Prospects for and status of the measurement of high x parton distributions at HERA

Inclusive neutral and charged current cross sections and structure functions measured at HERA-I are briefly reviewed. The impact of these measurements on parton density functions is discussed. The emphasis is put on the high x region. A first result obtained using the HERA-II data is also shown followed by future prospects for HERA.

hep-ph↗

arXiv2004

Experimental implications for a linear collider of SUSY dark matter scenario

This talk presents the detection issues for the lightest slepton \tildeτ_1 at a future e+e- TeV collider given the dark matter constraints set on the SUSY mass spectrum by the WMAP results. Two methods for measuring its mass m_{\tildeτ_1} and the resulting precision on the dark matter density are briefly discussed in the SUSY mSUGRA scenario with R-parity conservation when the mass difference between m_{\tildeτ_1} and that of the lightest neutralino is small (a few GeV). The analysis is performed with TESLA parameters in both head-on and crossing angle modes.

hep-ph↗

arXiv2002

Structure function results from H1

New structure function results from H1 are presented. The measurements cover a huge kinematical range for Q^2, the four momentum transfer squared, from 0.35, GeV^2 to 30,000, GeV^2, and for Bjorken x between \sim 5\cdot 10^{-6} and 0.65. At Q^2>100, GeV^2, full HERA, I data have been analyzed. The data are compared with a new QCD analysis. The impact of the HERA, I data on the parton density functions is discussed.

hep-ex↗

arXiv2002

Electron polarization measurement using a Fabry-Perot cavity at HERA

A new Compton longitudinal polarimeter currently under construction for HERA is presented. The key component of the polarimeter is a Fabry-Perot cavity located around the electron beam pipe. With such an optical cavity, a continuous laser power equivalent to 5 kW, much higher than those commercially available, can be achieved, leading to one backscattered photon per bunch crossing. This ``few-photon mode'' will allow a very precise determination of the calorimeter response with little systematic uncertainty. The electron polarization measurement at the per mill level is expected.

hep-ex↗

arXiv2001

Structure functions at large x

Structure function data together with other measurements from fixed-target deep inelastic scattering and hadron-hadron collider experiments which contribute to our knowledge of the parton density functions are reviewed. The inclusive cross-section measurements of neutral and charged current interactions at HERA are presented and their impact on the parton density functions is discussed. Future prospects for an improved knowledge of the parton density functions at large x are briefly mentioned.

hep-ph↗

arXiv2001

Searches for Leptoquarks, Squarks in $\not R_p$ SUSY and Excited Fermions at HERA

Various searches for leptoquarks, scalar quarks in $R_p$-violating supersymmetric models, and excited fermions performed by the HERA experiments H1 and ZEUS are reviewed. No evidence for new particle production was observed from data collected by both experiments since 1994 in either electron-proton and positron-proton collisions. Stringent limits derived on the masses and couplings of these new particles are compared whenever appropriate with those from LEP, the Tevatron and low energy experiments.

hep-ex↗

arXiv2000

New insights into the proton structure with ep collider HERA

Since its commissioning in 1991, the ep collider HERA has been running successfully for almost a decade without stopping improving its performance. In this report, the inclusive cross section and structure function measurements for the deep inelastic scattering of neutral and charged current processes in the full HERA kinematic domain are reviewed. The results are compared with the Standard Model expectations for the deep inelastic scattering processes. The new insights into the proton structure and on the underlying strong and electroweak interactions are discussed.

hep-ph↗

arXiv1999

New Structure Function Results at Low x and High Q^2 from HERA

A precise proton structure function F_2 at low x is measured. The data is interpreted in the framework of QCD with an extraction of gluon density xg. The charm contribution to F_2 is determined in an extended kinematic range. Neutral and charged current cross-sections at high Q^2 are also measured and compared with the Standard Model predictions.

hep-ph↗