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

## Abstract

A new tensor interaction is the only possibility to explain the \boldsymbol{2.8\sigma} $2.8\mathrm{\pi \x9d\x9b\x94}$ tension observed by the BaBar collaboration in the CP asymmetry in \boldsymbol{\tau\to K_S\pi\nu_\tau} $\mathrm{\pi \x9d\x9b\x95}\beta \x86\x92{\mathrm{\pi \x9d\x90\x8a}}_{\mathrm{\pi \x9d\x90\x92}}\mathrm{\pi \x9d\x9b\x91}{\mathrm{\pi \x9d\x9b\x8e}}_{\mathrm{\pi \x9d\x9b\x95}}$ 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 Watsonβs 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 \boldsymbol{D} $\mathrm{\pi \x9d\x90\x83}$ β \boldsymbol{\bar{D}} $\stackrel{\beta \x80\u038e}{\mathrm{\pi \x9d\x90\x83}}$ mixing. As a result, a confirmation of the tension at Belle II would point to light BSM physics.

- Authors:

- Los Alamos National Laboratory
- Paul Scherrer Institute
- University of Washington

- Publication Date:

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 1494965

- Grant/Contract Number:
- AC52-06NA25396; FG02-00ER41132

- Resource Type:
- Published Article

- Journal Name:
- SciPost Physics Proceedings

- Additional Journal Information:
- Journal Name: SciPost Physics Proceedings Journal Issue: 1

- Publisher:
- Stichting SciPost

- Country of Publication:
- Country unknown/Code not available

- Language:
- English

### Citation Formats

```
Cirigliano, Vincenzo, Crivellin, Andreas, and Hoferichter, Martin. A no-go theorem for non-standard explanations of the $\tau\to K_S\pi\nu_\tau$ CP asymmetry. Country unknown/Code not available: N. p., 2019.
Web. doi:10.21468/SciPostPhysProc.1.007.
```

```
Cirigliano, Vincenzo, Crivellin, Andreas, & Hoferichter, Martin. A no-go theorem for non-standard explanations of the $\tau\to K_S\pi\nu_\tau$ CP asymmetry. Country unknown/Code not available. doi:10.21468/SciPostPhysProc.1.007.
```

```
Cirigliano, Vincenzo, Crivellin, Andreas, and Hoferichter, Martin. Mon .
"A no-go theorem for non-standard explanations of the $\tau\to K_S\pi\nu_\tau$ CP asymmetry". Country unknown/Code not available. doi:10.21468/SciPostPhysProc.1.007.
```

```
@article{osti_1494965,
```

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

author = {Cirigliano, Vincenzo and Crivellin, Andreas and Hoferichter, Martin},

abstractNote = {A new tensor interaction is the only possibility to explain the \boldsymbol{2.8\sigma} 2.8 π tension observed by the BaBar collaboration in the CP asymmetry in \boldsymbol{\tau\to K_S\pi\nu_\tau} π β π π π π π 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 Watsonβs 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 \boldsymbol{D} π β \boldsymbol{\bar{D}} π βΎ mixing. As a result, a confirmation of the tension at Belle II would point to light BSM physics.},

doi = {10.21468/SciPostPhysProc.1.007},

journal = {SciPost Physics Proceedings},

number = 1,

volume = ,

place = {Country unknown/Code not available},

year = {2019},

month = {2}

}

DOI: 10.21468/SciPostPhysProc.1.007