ATLAS

Abstract:

Inclusive jet differential cross sections for the reaction ep → jet + X at Q2below 4 GeV2have been measured with the ZEUS detector at HERA using an integrated luminosity of 0.55 pb-1. These cross sections are given in the kinematic region 0.2 < y < 0.85, for jet pseudorapidities in the ep-laboratory range -1 < ηjet< 2 and refer to jets at the hadron level with a cone radius of one unit in the η - θ plane. These results correspond to quasi-real photoproduction at centre-of-mass energies in the range 130-270 GeV and, approximately, for jet pseudorapidities in the interval -3 < ηjet(λp CMS) < 0. These measurements cover a new kinematic regime of the partonic structure of the photon, at typical scales up to ∼300 GeV2and photon fractional momenta down to xγ∼ 10-2. Leading logarithm parton shower Monte Carlo calculations, which include both resolved and direct processes and use the predictions of currently available parametrisations of the photon parton distributions, describe in general the shape and magnitude of the measured ηjetand Etjetdistributions. © 1995.

Abstract:

Charge asymmetry has been measured using 19 039 W decays recorded by the Collider Detector at Fermilab during the 1992-93 run of the Tevatron Collider. The asymmetry is sensitive to the ratio of d and u quark distributions to x<0.01 at Q2MW2, where nonperturbative effects are minimal. It is found that of the two current sets of parton distributions, those of Martin, Roberts, and Stirling are favored over the sets most recently produced by the CTEQ Collaboration. The W asymmetry data provide stronger constraints on du ratio than the recent measurements of F2μnF2μp which are limited by uncertainties originating from deuteron corrections. © 1995 The American Physical Society.

Abstract:

This Letter describes a direct measurement of the W boson decay width, Γ(W), using the high-mass tail of the transverse mass spectrum of W→eν decays recorded by the Collider Detector at Fermilab. We findΓ(W)=2.11±0.28(stat)±0.16(syst) GeV and compare this direct measurement with indirect means of obtaining the width. © 1995 The American Physical Society.