Fundamental tests of P and C P symmetries using octet baryons at the J / ψ threshold
Year: 2024
Type: article
Abstract: We systematically investigate tests of the parity P and the combined parity and charge-conjugate C P symmetries from differential angular distributions of J / ψ decaying into the lowest-lying baryon pairs at BESIII and the next-generation super tau-charm facilities (STCFs). Large corrections from Z and W exchange induced parity-violating effects are found for J / ψ decays with large logarithms resummed up to O ( α s ) . The parity-violating asymmetries on the production and the decay sides of J / ψ are both estimated to be of O ( 10 − 4 ) , thus barely observable with the 10 billion J / ψ events currently collected at BESIII. Nevertheless, these asymmetries utilizing the current BESIII data already permit a measurement of the weak mixing angle with an absolute uncertainty δ s w 2 ≈ 0.09 , corresponding to the first determination of s w 2 at the J / ψ threshold. In the future, STCFs are estimated to improve this bound by a factor of ∼ 20 to δ s w 2 ≈ 0.005 within one year based on luminosity rescaling. We also obtain the 95% confidence level upper bounds on the electric dipole moments of the octet baryons, which are of O ( 10 − 18 ) e cm for BESIII and O ( 10 − 19 ) e cm for STCFs. These bounds are improved by 2 to 3 orders of magnitude in comparison with the only existing one on Λ from Fermilab. The method discussed in this work also paves a way for a first and direct measurement of the Ξ and Σ electric dipole moments. Published by the American Physical Society 2024
Authors: Yong Du, Xiao-Gang He, Jian-Ping Ma, Xin-Yu Du
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W4403485968