Signatures of complex new physics in $b\to c\tau \bar{\nu }$ transitions

Abstract

The anomalies in the measurements of $R_D$ and $R_{D^{\ast }}$ continue to provide motivation for physics beyond the Standard Model. In this work, we assume the new physics Wilson coefficients to be complex and find their values by doing a global fit to the present $b\to c\tau \bar{\nu }$ data. We find that the number of allowed solutions depend on the choice of the upper limit on $Br(B_c\to \tau \bar{\nu })$. We find that the forward-backward asymmetries in $B\to (D,D^{\ast })\tau \bar{\nu }$ decays have the capability to distinguish between different solutions. Further we calculate the maximum values of CP violating triple product asymmetries in $B\to D^{\ast }\tau \bar{\nu }$ decay allowed the current data. We observe that only one of the three CP asymmetries can be enhanced up to a maximum value of $\sim 2-3\%$ whereas the other asymmetries remain smaller.

18 pages, 5 figures, Accepted for publication in Nucl. Phys. B

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Cited by in corpus (9)

• The measurable angular distribution of ${\Lambda }_b^0\to {\Lambda }_c^{+}(\to {\Lambda }^0{\pi }^{+}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay
• New physics and the tau polarization vector in $b\to c\tau {\bar{\nu }}_{\tau }$ decays
• New physics effects on ${\Lambda }_b\to {\Lambda }_c^{\ast }\tau {\bar{\nu }}_{\tau }$ decays
• New physics in the angular distribution of $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay
• Extra gauge bosons and lepton flavor universality violation in ${\rm Y}$ and $B$ meson decays
• $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau },{\rho }^{-}{\nu }_{\tau },{\ell }^{-}{\bar{\nu }}_{\ell }{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decays with visible final-state kinematics
• Analysis of $b\to c\tau {\bar{\nu }}_{\tau }$ anomalies using weak effective Hamiltonian with complex couplings
• Visible energy and angular distributions of the charged particle from the $\tau -$decay in $b\to c\tau (\mu {\bar{\nu }}_{\mu }{\nu }_{\tau },\pi {\nu }_{\tau },\rho {\nu }_{\tau }){\bar{\nu }}_{\tau }$ reactions
• Addressing the $R_{\tau /\mu ,e}\left(D^{(\ast )}\right)$ puzzle through New Physics four-fermion operators and their impact on ${\Lambda }_b\to {\Lambda }_c\tau {\bar{\nu }}_{\tau }$ decay