A no-go theorem for non-standard explanations of the τto K_Sπν_τ CP asymmetry
read the original abstract
The CP asymmetry in $\tau\to K_S\pi\nu_\tau$, as measured by the BaBar collaboration, differs from the Standard Model prediction by $2.8\sigma$. Most non-standard interactions do not allow for the required strong phase needed to produce a non-vanishing CP asymmetry, leaving only new tensor interactions as a possible mechanism. We demonstrate that, contrary to previous assumptions in the literature, the crucial interference between vector and tensor phases is suppressed by at least two orders of magnitude due to Watson's final-state-interaction theorem. Furthermore, we find that the strength of the relevant CP-violating tensor interaction is strongly constrained by bounds from the neutron electric dipole moment and $D$-$\bar{D}$ mixing. These observations together imply that it is extremely difficult to explain the current $\tau\to K_S\pi\nu_\tau$ measurement in terms of physics beyond the Standard Model originating in the ultraviolet.
This paper has not been read by Pith yet.
Forward citations
Cited by 4 Pith papers
-
Generalized structure functions in semileptonic tau decays
Generalized structure functions are derived for tau decays including tensor beyond-SM contributions, enabling maximal model-independent use of data for CP/T violation studies.
-
$\tau^- \to \omega \pi^- \nu_\tau$ decay in R$\chi$T with tensor sources
The forward-backward asymmetry in τ⁻ → ω π⁻ ν_τ decay provides a sensitive probe for non-standard tensor interactions in resonance chiral theory.
-
Forward backward CP asymmetry in $\tau^- \to K \pi \nu_{\tau}$ in the Left-Right Inverse seesaw model
The Left-Right Inverse Seesaw model generates a non-decoupling scalar operator that enhances the differential forward-backward CP asymmetry A_CP^FB(s) near K* and K0* resonances in τ → Kπν_τ while leaving the integrat...
-
Dispersion relations: foundations
Pedagogical review explaining how causality implies analyticity and its use in scattering amplitudes, form factors, and resonance extraction in hadronic physics.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.