Study of CP violation in hyperon decays at Super Charm-Tau Factories with a polarized electron beam

Abstract

Non-leptonic two-body weak decays of baryons are an important tool to probe the combined charge-conjugation--parity symmetry (CP) violation. We explain why the decays of strange baryons provide complementary information to the decays of kaons. A model-independent parameterization of the non-leptonic decays of the $\Lambda$- and $\Xi$-baryons is reviewed, and the amplitudes are updated according to the latest experimental input. We demonstrate the potential of performing precision tests in strange baryon decays at the next generation electron-positron $J/\psi$ factories with luminosity of $10^{35}$ cm${}^{-2}$s${}^{-1}$. The copious production of spin-entangled hyperon-antihyperon pairs via the $J/\psi$ resonance allows for a direct comparison of the baryon and antibaryon decay properties. Using analytic approximations and numerical calculations, we study the quantitative impact of spin correlations and polarization in such CP tests. We show that by using a longitudinally-polarized electron beam, the statistical precision of the CP tests can be significantly improved compared to the experiments without polarized beams. Furthermore, we map out further directions for possible improvements, like analysis of incompletely reconstructed events or a combination of the isospin related processes. Altogether, these methods are promising for the observation of a statistically significant CP-violation signal with a strength corresponding to the standard model predictions. Our conclusions should encourage more detailed feasibility studies, including optimisation of the measurement methods and studies of systematic effects. Finally, our results call for an update of the theory predictions with increased precision.

contribution to Snowmass 2021, 59 pages, 18 figures, 7 tables

References in corpus (10)

• Observation of $CP$ violation in charm decays
• Precise Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters in the Neutral Kaon System
• Comprehensive Amplitude Analysis of $\gamma \gamma \to {\pi }^{+}{\pi }^{-},{\pi }^0{\pi }^0$ and $\overline{K}K$ below 1.5 GeV
• Weak phases and CP-symmetry tests in sequential decays of entangled double-strange baryons
• ${\Sigma }^{+}$ and ${\bar{\Sigma }}^{-}$ polarization in the $J/\psi$ and $\psi (3686)$ decays
• A Review on Partial-wave Dynamics with Chiral Effective Field Theory and Dispersion Relation
• The BESIII Physics Programme
• Measurements of the branching fractions of the semileptonic decays ${\Xi }_c^0\to {\Xi }^{-}{\ell }^{+}{\nu }_{\ell }$ and the asymmetry parameter of ${\Xi }_c^0\to {\Xi }^{-}{\pi }^{+}$
• ${\epsilon }^{\prime }/\epsilon$ in the Standard Model at the Dawn of the 2020s
• The ${\epsilon }^{\prime }/\epsilon$-Story: 1976-2021

Cited by in corpus (20)

• STCF Conceptual Design Report: Volume 1 -- Physics & Detector
• Tests of $CP$ symmetry in the entangled ${\Xi }^0-{\bar{\Xi }}^0$ Pairs
• Octet baryon isovector charges from $N_f=2+1$ lattice QCD
• Search for $CP$ violation and measurement of branching fractions and decay asymmetry parameters for ${\Lambda }_c^{+}\to \Lambda h^{+}$ and ${\Lambda }_c^{+}\to {\Sigma }^0{h}^{+}$ ($h=K,\pi$)
• Test of $CP$ Symmetry in Hyperon to Neutron Decays
• $B\to K+$invisible, dark matter, and $CP$ violation in hyperon decays
• Production and decay of polarized hyperon-antihyperon pairs
• Production and decay of hyperons in a transversely polarized electron-positron collider
• Semileptonic decays of spin-entangled baryon-antibaryon pairs
• Prospects of $CP$ violation in $\Lambda$ decay with polarized electron beam at STCF
• Stringent test of $CP$ symmetry in ${\Sigma }^{+}$ hyperon decays
• Novel method to extract the femtometer structure of strange baryons using the vacuum polarization effect
• Measurements of the absolute branching fractions of ${\Omega }^{-}$ decays and test of the $\Delta I=1/2$ rule
• Remarks on strong phase shifts in weak nonleptonic baryon decays
• CP violation in the hyperon decays $\Sigma \to N\pi$
• Tests of CP symmetry in entangled hyperon anti-hyperon pairs at BESIII
• Precise Measurement of Matter-Antimatter Asymmetry with Entangled Hyperon Antihyperon Pairs
• Prospects for $P$ and $CP$ violation in ${\Lambda }_c^{+}$ decays with polarized beam at Super Tau-Charm Facility
• New Physics Searches at Kaon and Hyperon Factories
• New Window on Matter-Antimatter Differences