Measurement of High-Q^2 Charged-Current e^+p Deep Inelastic Scattering Cross Sections at HERA

ZEUS Collaboration

Paper

Measurement of High-Q^2 Charged-Current e^+p Deep Inelastic Scattering Cross Sections at HERA

Abstract

The e^+p charged-current deep inelastic scattering cross sections,

for Q^2 between 200 and 60000 GeV^2, and

and

for Q^2 > 200 GeV^2, have been measured with the ZEUS detector at HERA. A data sample of 47.7 pb^-1, collected at a center-of-mass energy of 300 GeV, has been used. The cross section

falls by a factor of about 50000 as Q^2 increases from 280 to 30000 GeV^2. The double differential cross section

has also been measured. A comparison between the data and Standard Model (SM) predictions shows that contributions from antiquarks (

and

) and quarks (d and s) are both required by the data. The predictions of the SM give a good description of the full body of the data presented here. A comparison of the charged-current cross section

with the recent ZEUS results for neutral-current scattering shows that the weak and electromagnetic forces have similar strengths for Q^2 above

. A fit to the data for

with the Fermi constant

and

as free parameters yields

and

. Results for

, where the propagator effect alone or the SM constraint between

and

have been considered, are also presented.