CP Violation in Hadronic tau Decays

Abstract

We re-examine CP violation in the Delta S = 0 decays tau -> N pi nu_tau (N=2,3,4). We assume that the new physics (NP) is a charged Higgs. We show that there is no NP contribution to tau -> pi pi nu_tau, which means that no CP violation is expected in this decay. On the other hand, NP can contribute to tau -> N pi nu_tau (N=3,4). These are dominated by the intermediate resonant decays tau -> omega pi nu_tau, tau -> rho pi nu_tau and tau -> a_1 pi nu_tau. We show that the only sizeable CP-violating effects which are possible are in tau -> a_1 pi nu_tau -> 4 pi nu_tau (polarization-dependent rate asymmetry) and tau -> omega pi nu_tau (triple-product asymmetry).

21 pages, 2 figures (enclosed). Numerical analysis added; references renumbered; figure changed. Analysis and conclusions unchanged

References in corpus (1)

• Exclusive branching fraction measurements of semileptonic tau decays into three charged hadrons, ${\tau }^{-}\to \varphi {\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{-}\to \varphi K^{-}{\nu }_{\tau }$

Cited by in corpus (7)

• New Physics at a Super Flavor Factory
• CP violation in $B\to D\tau {\nu }_{\tau }$ using multi-pion tau decays
• CP asymmetry in $\tau \to K_S\pi {\nu }_{\tau }$ decays within the Standard Model and beyond
• CP violation in tau -> K pi pi nu_tau
• Nonstandard interactions of tau neutrino via charged Higgs and $W^{\prime }$ contribution
• Direct CP violation in ${\tau }^{\pm }\to K^{\pm }{\rho }^0(\omega ){\nu }_{\tau }\to K^{\pm }{\pi }^{+}{\pi }^{-}{\nu }_{\tau }$
• Second-class current effects from isospin breaking in tau-->omega pi nu_tau