RESUMEN
We present a measurement of the effective weak mixing angle parameter sin^{2}θ_{eff}^{â} in pp[over ¯]âZ/γ^{*}âµ^{+}µ^{-} 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. The measured value of sin^{2}θ_{eff}^{â}[µµ]=0.23016±0.00064 is further combined with the result from the D0 measurement in pp[over ¯]âZ/γ^{*}âe^{+}e^{-} events, resulting in sin^{2}θ_{eff}^{â}[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.
RESUMEN
We report evidence for a narrow structure, X(5568), in the decay sequence X(5568)âB_{s}^{0}π^{±}, B_{s}^{0}âJ/ψÏ, J/ψâµ^{+}µ^{-}, ÏâK^{+}K^{-}. This is evidence for the first instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m=5567.8±2.9(stat)_{-1.9}^{+0.9}(syst) MeV/c^{2} and Γ=21.9±6.4(stat)_{-2.5}^{+5.0}(syst) MeV/c^{2}. If the decay is X(5568)âB_{s}^{*}π^{±}âB_{s}^{0}γπ^{±} with an unseen γ, m(X(5568)) will be shifted up by m(B_{s}^{*})-m(B_{s}^{0})â¼49 MeV/c^{2}. This measurement is based on 10.4 fb^{-1} of pp[over ¯] collision data at sqrt[s]=1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.