ZEUS at the HERA Accelerator )
نویسندگان
چکیده
Production of electroweak vector bosons W and Z in electron-proton collisions at centre of mass energy ps = 300GeV was studied. The data sample used corresponds to the integrated luminosity L = 37:4 pb 1 collected in the ZEUS experiment at HERA during 1993{1997. Hadronic decay channel of W=Z bosons with high transverse energy (High-ET ) nal states was investigated, looking for an excess of events in the inclusive di-jet invariant mass distribution. The following limits on the cross sections for the reactions e + p ! e + W=Z + X were obtained at the 95% con dence level: W < 15:4 pb and Z < 3:7 pb. These results give the following limits on the parameters and describing the triple gauge boson coupling WW : 15:5 < < 11:5 and 18:5 < < 18:5. The elastic channel of Z boson production e + p ! e + p + Z was also investigated leading to the tighter limit on the cross section: Z < 1:1 pb. Results presented in this analysis were obtained without using PAW.
منابع مشابه
The Spectrometer System for Measuring ZEUS Luminosity at HERA
The upgrade of the HERA accelerator has provided much increased collider luminosity. In turn, the improvements have necessitated a new design for the ZEUS luminosity measurements. The intense synchrotron radiation field, as well as the high probability of a bremsstrahlung photon in each bunch crossing, posed new experimental constraints. In this report, we describe how these challenges were met...
متن کاملRecent Results from HERA Experiments
HERA is an electron1-proton (ep) collider operating in DESY in Hamburg, Germany. At HERA, electrons of energy Ee = 27.6 GeV collide with protons of energy Ep = 820 or 920 GeV, corresponding to a center-of-mass energy of 301 or 319 GeV, respectively. In autumn 2003 the HERA accelerator started operation of the second phase of its ep collider programme, so called HERA II. The e+p and ep data coll...
متن کاملThe Structure Functions and Low X Working Group Summary
The structure functions and low x working group summary of DIS06. 1. Recent results from HERA We begin by discussing new results from HERA. In autumn 2003 the accelerator started the second phase of its ep collider programme (HERA-II). The e + p and e − p data collected by the H1 and ZEUS experiments since then, were taken with longitudinally polarised positron and electron beams for the first ...
متن کاملar X iv : h ep - p h / 99 09 22 3 v 1 2 S ep 1 99 9 IC - HEP / 99 - 03 Future ep Physics : The Outlook for HERA
The luminosity of the electron-proton collider, HERA, will be increased by a factor of five during the long shutdown in the year 2000. At the same time longitudinal lepton beam polarisation will be provided for the collider experiments H1 and ZEUS. These far reaching upgrades to the machine will be matched by upgrades to the detectors. The result will be a unique facility for the study of the s...
متن کاملThe ZEUS Forward Plug Calorimeter with Lead-Scintillator Plates and WLS Fiber Readout
A Forward Plug Calorimeter (FPC) for the ZEUS detector at HERA has been built as a shashlik lead-scintillator calorimeter with wave length shifter fiber readout. Before installation it was tested and calibrated using the X5 test beam facility of the SPS accelerator at CERN. Electron, muon and pion beams in the momentum range of 10 to 100 GeV/c were used. Results of these measurements are presen...
متن کاملIsolated photon production in Deep Inelastic Scattering at HERA with ZEUS
Isolated hard photons have been measured accompanied by jets in Deep Inelastic Scattering using the ZEUS detector at HERA. Preliminary results for the cross sections are presented.
متن کامل