Measurement of the effective weak mixing angle using bb̄, cc̄ and ss̄ final states at the CEPC

The proposed Circular Electron Positron Collider (CEPC) is expected to provide adequate events around the Z boson mass pole, allowing high precision determination on the effective weak mixing angle. Specifically, one can acquire large data samples of the Z→ bb̄ Z → b b ¯ , Z→ cc̄ Z → c c ¯ and Z→ ss̄ Z → s s ¯ events with high purity, even though the efficiencies of the jet tagging are limited to ensure a good separation between different flavors. According to recent studies of the detector and reconstruction algorithms, with the new jet tagging method at the CEPC detector which gives a purity of $$99.9%$$ 99.9 % for the bb̄ b b ¯ and cc̄ c c ¯ samples and $$97%$$ 97 % for the ss̄ s s ¯ sample, the corresponding uncertainties on the effective weak mixing angle determined from those samples are better than 10⁻⁴ 10 - 4 using data collected within 1 month. It allows high precision determinations of the effective weak mixing angle from different quark flavors especially for c and s quarks, which is essential to the standard model global test and potential new physics searches.