Measurement of the Effective Weak Mixing Angle in pp[over ¯]→Z/γ^{*}→ℓ^{+}ℓ^{-} Events

Area of Science:

• Particle Physics
• High Energy Physics
• Electroweak Interactions

Background:

• The Standard Model of particle physics describes fundamental forces and particles.
• The weak mixing angle is a key parameter in electroweak theory.
• Precise measurements test the Standard Model and search for new physics.

Purpose of the Study:

• To measure the effective weak mixing angle parameter (sin^{2}θ_{eff}^{ℓ}) in proton-antiproton collisions.
• To improve the precision of sin^{2}θ_{eff}^{ℓ} measurements at hadron colliders.
• To provide a precise determination using Z/γ* couplings to light quarks.

Main Methods:

• Analysis of Z/γ* → μ⁺μ⁻ events collected by the D0 detector at the Fermilab Tevatron.
• Utilizing 1.96 TeV center-of-mass energy and 8.6 fb⁻¹ of integrated luminosity.
• Combining results with previous D0 measurements of Z/γ* → e⁺e⁻ decays.

Main Results:

• The measured value of sin^{2}θ_{eff}^{ℓ}[μμ] is 0.23016 ± 0.00064.
• The combined result from μ⁺μ⁻ and e⁺e⁻ channels is sin^{2}θ_{eff}^{ℓ}[comb] = 0.23095 ± 0.00040.
• This represents the most precise measurement from a single experiment at a hadron collider.

Conclusions:

• The combined result provides the most precise determination of sin^{2}θ_{eff}^{ℓ} using light quark couplings.
• This precise measurement serves as a stringent test of the Standard Model.
• Future comparisons with theoretical predictions will further probe electroweak physics.