Pre-feasibility Study Of Measuring The Electro-Weak Mixing Angle Sinθ_W For Low Momentum Transfer At BEPC And B-factory

In this thesis we studied the measuring possibility of the electro-weak mixing angle sin θ_W for low momentum transfer at BEPC and B-factory (Pre-feasibility Study ). As the complement for the study of high-energy collide processes, sin θ_W for low momentum transfer can test the weak-interaction standard model for Low Momentum Transfer. Here we consider the processes e⁺e^- → Ï„⁺Ï„^- ,one class of low-energy electroweak measurement for the determination of a parity-violating asymmetry A_pv = (σ_R-σ_L)/(σ_R-σ_L) , where σ_R(L) is the cross section for finial right (left)-handed Ï„.A_PV arises from the difference of Z⁰ coupled with right-hand fermion and left-hand fermion ,the difference is direct dependent on the weak mixing angle θ_W Thus we can measure the Weinberg angle by measuring the A_PV . We hope to use the strenghthen effect of the resonance,study the resonance φ(3770), φ(3686) at BEPC and the resonance T(9460) at B-factory at the around of the resonance peak and analysis the the relationship between the A_PV and sin² θ .Our conclusion is that the luminance of BEPC and B-factory is expect to increase 1-2 order for direct measuring sin θ_W at charm quark field and bottom quark field (accurracy is about 2%).