Polarized and un-polarized ${\mathcal{R}}_{K^{\ast }}$ in and beyond the SM

Abstract

The Standard Model (SM) is lepton flavor universal, and the recent measurements of lepton flavor universality in $B\to (K,K^{\ast }){\ell }^{+}{\ell }^{-}$, for $\ell =\mu ,e$, decays now lie close to the SM predictions. However, this is not the case for the $\tau$ to $\mu$ ratios in these decays, where there is still some window open for the new physics (NP), and to accommodate them various extensions to the SM are proposed. It will be interesting to identify some observables which are not only sensitive on the parametric space of such NP models but also have some discriminatory power. We find that the polarization of the $K^{\ast }$ may play an important role, therefore, we have computed the unpolarized and polarized lepton flavor universality ratios of $\tau$ to $\mu$ in $B\to K^{\ast }{\ell }^{+}{\ell }^{+}$, $\ell =\mu ,\tau$ decays. The calculation shows that in most of the cases, the values of the various proposed observables fall within the current experimental sensitivity, and their study at some on going and future experiments will serve as a tool to segregate the variants of the NP models.

18 pages, 7 figures, Tables II and III updated and subsequent changes were incorporated in related Tables and Figures

References in corpus (28)

• Weak Decays Beyond Leading Logarithms
• Test of lepton universality with $B^0\to K^{\ast 0}{\ell }^{+}{\ell }^{-}$ decays
• Systematic approach to exclusive B ->V l^+l^-, V gamma decays
• $B\to V{\ell }^{+}{\ell }^{-}$ in the Standard Model from Light-Cone Sum Rules
• On the Standard Model predictions for $R_K$ and $R_{K^{\ast }}$
• Test of lepton universality in beauty-quark decays
• Global analysis of $b\to s\ell \ell$ anomalies
• Patterns of New Physics in $b\to s{\ell }^{+}{\ell }^{-}$ transitions in the light of recent data
• Measurement of $CP$-averaged observables in the $B^0\to K^{\ast 0}{\mu }^{+}{\mu }^{-}$ decay
• Emerging patterns of New Physics with and without Lepton Flavour Universal contributions
• New Physics in $b\to s{\mu }^{+}{\mu }^{-}$ after the Measurement of $R_{K^{\ast }}$
• Test of lepton-flavor universality in $B\to K^{\ast }{\ell }^{+}{\ell }^{-}$ decays at Belle
• Diagnosing lepton-nonuniversality in $b\to s\ell \ell$
• Continuing search for new physics in $b\to s\mu \mu$ decays: two operators at a time
• Test of lepton universality in $b\to s{\ell }^{+}{\ell }^{-}$ decays
• The $B$ Anomalies and New Physics in $b\to s{e}^{+}{e}^{-}$
• Measurement of lepton universality parameters in $B^{+}\to K^{+}{\ell }^{+}{\ell }^{-}$ and $B^0\to K^{\ast 0}{\ell }^{+}{\ell }^{-}$ decays
• Implications of new evidence for lepton-universality violation in $b\to s{\ell }^{+}{\ell }^{-}$ decays
• To (b)e or not to (b)e: No electrons at LHCb
• QED Corrections in $\bar{B}\to \bar{K}{\ell }^{+}{\ell }^{-}$ at the Double-Differential Level
• $b\to s\ell \ell$ Global Fits after $R_{K_S}$ and $R_{K^{\ast +}}$
• Lessons from the $B^{0,+}\to K^{\ast 0,+}{\mu }^{+}{\mu }^{-}$ angular analyses
• Analytic calculation of two-loop QCD corrections to b\to s\ell^+\ell^- in the high q^2 region
• $b\to s{\ell }^{+}{\ell }^{-}$ Transitions in Two-Higgs-Doublet Models
• Are we overlooking Lepton Flavour Universal New Physics in $b\to s\ell \ell$ ?
• On the new LHCb angular analysis of $B\to K^{\ast }{\mu }^{+}{\mu }^{-}$: Hadronic effects or New Physics?
• QED in $\bar{B}\to \bar{K}{\ell }^{+}{\ell }^{-}$ LFU ratios: Theory versus Experiment, a Monte Carlo Study
• New physics in $B\to K^{\ast }{\tau }^{+}{\tau }^{-}$: A model independent analysis