Thursday, July 4, 2013

1307.0770 (CDF Collaboration et al.)

Indirect measurement of $sin^2θ_W$ (M_W) using e+e- pairs in the
Z-boson region with $p\bar{p}$ collisions at a center-of-momentum energy of
1.96 TeV

CDF Collaboration, T. Aaltonen, S. Amerio, D. Amidei
Drell-Yan lepton pairs are produced in the process $p\bar{p} \rightarrow e^+e^- + X$ through an intermediate $\gamma^*/Z$ boson. The lepton angular distributions are used to provide information on the electroweak-mixing parameter $sin^2\theta_W$ via its observable effective-leptonic $sin^2\theta_W$, or $sin^2\theta^{lept}_{eff}$. A new method to infer $sin^2\theta_W$, or equivalently, the W-boson mass M_W, 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 $p\bar{p}$ collisions at a center-of-momentum energy of 1.96 TeV. The value of $sin^2\theta^{lept}_{eff}$ is found to be 0.2328 +- 0.0011. Within a specified context of the standard model, this results in $sin^2\theta_W$ = 0.2246 +- 0.0011 which corresponds to a W-boson mass of 80.297 +- 0.055 GeV/c^2, in agreement with previous determinations in electron-position collisions and at the Tevatron collider.
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