New physics analysis of ${\Lambda }_b\to ({\Lambda }^{\ast }(\to p{K}^{-}),\Lambda (\to p\pi ))({\mu }^{+}{\mu }^{-},\nu \bar{\nu })$ baryonic decays under SMEFT framework

Abstract

The di-leptons and di-neutrinos observed in the final states of flavor-changing neutral b decays provide an ideal platform for probing physics beyond the standard model. Although the latest measurements of $R_{K^{(\ast )}}$ agree well with the standard model prediction, there exists several other observables such as $P_5^{\prime }$, $\mathcal{B}(B_s\to \varphi {\mu }^{+}{\mu }^{-})$ and $\mathcal{B}(B_s\to {\mu }^{+}{\mu }^{-})$ in $b\to s\ell \ell$ transition decays that shows deviation from the standard model prediction. Similalry, very recently Belle II collaboration reported a more precise upper bound of $\mathcal{B}(B\to K^{+}\nu \bar{\nu })<4.1\times 10^{-5}$ by employing a new inclusive tagging approach and it also deviates from the standard model expectation. The $b\to s{l}^{+}{l}^{-}$ and $b\to s\nu \bar{\nu }$ transition decays are related not only in the standard model but also in beyond the standard model physics due to $SU(2{)}_L$ gauge symmetry, and can be most effectively investigated using the standard model effective field theory formalism. Additionally, the $b\to s\nu \bar{\nu }$ decay channels are theoretically cleaner than the corresponding $b\to s{l}^{+}{l}^{-}$ decays, as these processes do not get contributions from non-factorizable corrections and photonic penguin contributions. In this context, we study ${\Lambda }_b\to ({\Lambda }^{\ast }(\to p{K}^{-}),\Lambda (\to p\pi ))({\mu }^{+}{\mu }^{-},\nu \bar{\nu })$ baryonic decays undergoing $b\to s{\ell }^{+}{\ell }^{-}$ and $b\to s\nu \bar{\nu }$ quark level transitions in a standard model effective field theory formalism. We give predictions of several observables pertaining to these decay channels in the standard model and in case of several new physics scenarios.

Comments: 22 Pages, 6 Figures, 13 Tables