Abstract
We present a measurement of the effective weak mixing angle parameter sin^{2}θ_{eff}^{ℓ} in pp[over ¯]→Z/γ^{*}→μ^{+}μ^{-} events at a center-of-mass energy of 1.96TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb^{-1} of integrated luminosity. The measured value of sin^{2}θ_{eff}^{ℓ}[μμ]=0.23016±0.00064 is further combined with the result from the D0 measurement in pp[over ¯]→Z/γ^{*}→e^{+}e^{-} events, resulting in sin^{2}θ_{eff}^{ℓ}[comb]=0.23095±0.00040. This combined result is the most precise measurement from a single experiment at a hadron collider and is the most precise determination using the coupling of the Z/γ^{*} to light quarks.
Highlights
10LPC, Universite Blaise Pascal, CNRS/IN2P3, Clermont, F-63178 Aubiere Cedex, France 11LPSC, Universite Joseph Fourier Grenoble 1, CNRS/IN2P3, Institut National Polytechnique de Grenoble, F-38026 Grenoble Cedex, France 12CPPM, Aix-Marseille Universite, CNRS/IN2P3, F-13288 Marseille Cedex 09, France 13LAL, Univ
We present a measurement of the effective weak mixing angle parameter sin2θleff in pp → Z=γà → μþμ− events at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider and corresponding to 8.6 fb−1 of integrated luminosity
It governs the mechanism of spontaneous symmetry breaking of SUð2Þ × Uð1Þ in which the original vector boson fields W and B0 are transformed to the physical WÆ, Z, and γ states
Summary
It is customary to quote the charged-lepton effective weak mixing angle parameter sin θleff, determined by measurements of observables around the Z-boson mass pole (MZ). An independent determination of the effective weak mixing angle at hadron colliders that is based on different combinations of fermions in the initial and final state from those in the eþe−. Forward (F) or backward (B) events are defined as those for which cos θà > 0 or cos θà < 0, where θà is the angle between the negatively charged lepton direction and the incoming proton direction in the Collins-Soper frame [2]
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