Prospects of CP violation in Λ decay with a polarized electron beam at the STCF*

Zeng, Sheng; Xu, Yuchun; Zhou, Xiaorong; Qin, J.; Zheng, B.

doi:10.1088/1674-1137/ace9c5

Cited by 3 publications

(1 citation statement)

References 26 publications

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“…The BESIII collaboration achieved a significant milestone, accumulating a staggering amount of events by 2019, with many of these events producing polarized baryon-antibaryon pairs [36]. Leveraging the entanglement of final states has enabled the extraction of observables at an unprecedented level of accuracy, offering an excellent platform for probing new physics (NP) [37,38]. Moreover, the future STCF is designed to take data, corresponding to events per year [39], promising even higher precision in relevant processes.…”

Section: J/ψmentioning

confidence: 99%

New signature of low mass Z′ in J/ψ decays*

Geng 耿,

Liu 劉,

Zhang 张

2024

Chinese Phys. C

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We explore a new approach to search for a low-mass $Z^{\prime}$ particle through $J/\psi$ decays by identifying its existence through parity-violating phenomena in the isospin-violating final states of $\Lambda\overline{\Sigma}^{0}$ and the corresponding charge conjugated states of $\overline{\Lambda}\Sigma^{0}$. Our investigation centers on a generation-independent and leptophobic $Z^{\prime}$ with its mass below 10 GeV.Given the present experimental conditions at the Beijing Spectrometer III~(BESIII) and the anticipated opportunities at the Super Tau Charm Factory~(STCF), we conduct Monte-Carlo simulations to predict possible events at both facilities.Notably, we foresee a substantial enhancement in the precision of the lower limit estimation of $\alpha_{\text{NP}}$ as well as a reduction in statistical uncertainty with upcoming STCF experiments.Furthermore, it is essential to highlight that a null result in the measurement of $\alpha_{\text{NP}}$ would impose stringent constraints, requiring the $Z^{\prime}-q-q$ couplings to be on the order of $10^{-2}$. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Article funded by SCOAP3 and published under licence by Chinese Physical Society and the Institute of High Energy Physics of the Chinese Academy of Science and the Institute of Modern Physics of the Chinese Academy of Sciences and IOP Publishing Ltd.

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Section: J/ψmentioning

confidence: 99%

New signature of low mass Z′ in J/ψ decays*

Geng 耿,

Liu 劉,

Zhang 张

2024

Chinese Phys. C

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Production and decay of hyperons in a transversely polarized electron-positron collider

Cao,

Liang,

Ping

2024

Phys. Rev. D

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The self-polarization of relativistic electrons or positrons moving in a magnetic field at a storage ring occurs through the emission of spin-flip synchrotron radiation, known as the Sokolov-Ternov effect. The resulting transverse polarizations of the colliding electrons and positrons, away from the depolarization resonances, allow for precise investigation of the spin entangled hyperon-antihyperon pairs via virtual photon or charmonium decay. The feasibility study reveals a promising increase in the statistical sensitivity of the CP violation signal after considering the transverse polarizations of the lepton beams. Published by the American Physical Society 2024

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Fundamental tests of P and CP symmetries using octet baryons at the J/ψ threshold

Du,

He,

et al. 2024

Phys. Rev. D

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We systematically investigate tests of the parity P and the combined parity and charge-conjugate CP 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(αs). 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 δsw2≈0.09, corresponding to the first determination of sw2 at the J/ψ threshold. In the future, STCFs are estimated to improve this bound by a factor of ∼20 to δsw2≈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

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Prospects of CP violation in Λ decay with a polarized electron beam at the STCF*

Cited by 3 publications

References 26 publications

New signature of low mass Z′ in J/ψ decays*

New signature of low mass Z′ in J/ψ decays*

Production and decay of hyperons in a transversely polarized electron-positron collider

Fundamental tests of P and CP symmetries using octet baryons at the J/ψ threshold

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