Drell-Yan lepton pairs are produced in the process $pbar{p} rightarrow e^+e^- + X$ through an intermediate $gamma^*/Z$ boson. The lepton angular distributions are used to provide information on the electroweak-mixing parameter $sin^2theta_W$ via its observable effective-leptonic $sin^2theta_W$, or $sin^2theta^{lept}_{eff}$. A new method to infer $sin^2theta_W$, or equivalently, the W-boson mass M_W in the on-shell scheme, is developed and tested using a previous CDF Run II measurement of angular distributions from electron pairs in a sample corresponding to 2.1 fb-1 of integrated luminosity from $pbar{p}$ collisions at a center-of-momentum energy of 1.96 TeV. The value of $sin^2theta^{lept}_{eff}$ is found to be 0.2328 +- 0.0010. Within a specified context of the standard model, this results in $sin^2theta_W$ = 0.2246 +- 0.0009 which corresponds to a W-boson mass of 80.297 +- 0.048 GeV/c^2, in agreement with previous determinations in electron-position collisions and at the Tevatron collider.
تحميل البحث