Study of charged-current ep interactions at Q² > 200 GeV² with the ZEUS detector at HERA

The cross sections for the deep inelastic charged-current interactions e⁺p → ν̄X and e^-p → νX have been measured in the kinematic region x > 0.006 and Q² > 200GeV², using the e⁺p and e^-p data collected with the ZEUS detector during 1993 and 1994. For the integrated cross sections, σ_e+→ν̄X(Q²>200 GeV²) = 30.3_{- 4.2} ^{+ 5.5} [stat] _-2.6 ^+1.6 [syst] pb σ_e-p→νX(Q²>200 GeV²) = 54.7^-9.8+15.9 [stat] _-3.4 ^+2.8 [syst] pb are obtained, in good agreement with the Standard Model expectations of 32.3pb and 65.8pb. The differential cross sections have been measured as functions of Q², x and y. The differences between e⁺p and e^-p scattering, which are expected from the V-A helicity structure of the weak interaction and from the quark content of the proton, are clearly observed. No significant deviation from the Standard Model predictions is found. The measured Q² dependence of the differential cross sections for e⁺ and c^- induced CC DIS reactions is used to determine the W mass. The measured value of M_W is 79 _{-7 -4} ^{+8 +4} GeV, in good agreement with direct measurements performed at pp̄ colliders. A jet analysis has been performed and CC events with multiple jets have been observed. The distributions of the jet transverse momentum and rapidity as well as transverse energy flow jet profiles have been measured and are compared to the script O sign(α_s) predictions of the ARIADNE and MEPS Monte Carlo models. Good agreement is observed in both the jet profiles and the jet rates. A search for charged-current events with a large rapidity gap between the observed hadronic system and the outgoing proton system yielded one candidate event in the e⁺p sample, corresponding to a cross section of σ_e+p→ν̄X(Q² > 200 GeV²; ηmax < 2.5) = 0.8 _-0.7 ^+1.8 [stat] ±0.1 [syst] pb.