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A no-go theorem for non-standard explanations of the $\tau\to K_S\pi\nu_\tau$ CP asymmetry

by V. Cirigliano, A. Crivellin, M. Hoferichter

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Submission summary

Authors (as registered SciPost users): Martin Hoferichter
Submission information
Preprint Link: scipost_201811_00001v1  (pdf)
Date accepted: 2019-01-15
Date submitted: 2018-11-02 01:00
Submitted by: Hoferichter, Martin
Submitted to: SciPost Physics Proceedings
Proceedings issue: The 15th International Workshop on Tau Lepton Physics (TAU2018)
Ontological classification
Academic field: Physics
  • High-Energy Physics - Experiment
  • High-Energy Physics - Phenomenology
  • Nuclear Physics - Theory
Approach: Theoretical


A new tensor interaction is the only possibility to explain the $2.8\sigma$ tension observed by the BaBar collaboration in the CP asymmetry in $\tau\to K_S\pi\nu_\tau$ with physics beyond the Standard Model (BSM) realized above the electroweak scale. However, the strong phase generated by the interference between vector and tensor phases is suppressed by at least two orders of magnitude due to Watson's final-state-interaction theorem, and the strength of the CP-violating tensor interaction is strongly constrained by bounds from the neutron electric dipole moment and $D$-$\bar{D}$ mixing. As a result, a confirmation of the tension at Belle II would point to light BSM physics.

Published as SciPost Phys. Proc. 1, 007 (2019)

Reports on this Submission

Anonymous Report 1 on 2018-12-12 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_201811_00001v1, delivered 2018-12-12, doi: 10.21468/SciPost.Report.735


The conference contribution under consideration is entirely based on the reviewed journal publication Phys. Rev. Lett. 120 (2018) 141803. It is well written and clear. Hence, in my opinion there is no need for a more detailed report.

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