Hint of a new scalar interaction in LHCb data?

Journal Article · 03 June 2024 · European Physical Journal. C, Particles and Fields (Online)

DOI: https://doi.org/10.1140/epjc/s10052-024-12890-8 · OSTI ID:2370455

Datta, Alakabha; Marfatia, Danny; Mukherjee, Lopamudra

Abstract We explain recent LHCb measurements of the lepton universality ratios, $$$$R_{D^{(*)}}^{\tau /\ell }\equiv \frac{\mathcal {B}(\bar{B} \rightarrow D^{(*)+} \tau ^- \bar{\nu }_\tau )}{\mathcal {B}(\bar{B} \rightarrow D^{(*)+}\ell ^- \bar{\nu }_\ell )}$$$$ $R_{D^{(\ast )}}^{\tau /\ell }\equiv \frac{B(\overline{B}\to D^{(\ast )+}{\tau }^{-}{\overline{\nu }}_{\tau })}{B(\overline{B}\to D^{(\ast )+}{\ell }^{-}{\overline{\nu }}_{\ell })}$ and $$$${R(\Lambda _c^+)}^{\tau /\ell } \equiv \frac{\mathcal {B}(\Lambda _b \rightarrow \Lambda _c^+ \tau ^- \bar{\nu }_{\tau })}{\mathcal {B}(\Lambda _b \rightarrow \Lambda _c^+ \ell ^- \bar{\nu }_{\ell })}$$$$ ${R\left({\Lambda }_c^{+}\right)}^{\tau /\ell }\equiv \frac{B({\Lambda }_b\to {\Lambda }_c^{+}{\tau }^{-}{\overline{\nu }}_{\tau })}{B({\Lambda }_b\to {\Lambda }_c^{+}{\ell }^{-}{\overline{\nu }}_{\ell })}$ with $$$$\ell =\mu $$$$ $\ell =\mu$ , via new physics that affects $$$$R_D^{\tau /\ell }$$$$ $R_D^{\tau /\ell }$ and $$$$R(\Lambda _c^+)^{\tau /\ell }$$$$ $R{\left({\Lambda }_c^{+}\right)}^{\tau /\ell }$ but not $$$$R_{D^*}^{\tau /\ell }$$$$ $R_{D^{\ast }}^{\tau /\ell }$ . The scalar operator in the effective theory for new physics is indicated. We find that the forward-backward asymmetry and $$$$\tau $$$$ $\tau$ polarization in $$$$\bar{B} \rightarrow D^+ \tau ^{-} \bar{\nu }_{\tau }$$$$ $\overline{B}\to D^{+}{\tau }^{-}{\overline{\nu }}_{\tau }$ and $$$$\Lambda _b \rightarrow \Lambda _c^+ \tau ^- \bar{\nu }_{\tau }$$$$ ${\Lambda }_b\to {\Lambda }_c^{+}{\tau }^{-}{\overline{\nu }}_{\tau }$ decays are significantly affected by the scalar interaction. We construct a simple two Higgs doublet model as a realization of our scenario and consider lepton universality in semileptonic charm and top decays, radiative B decay, B -mixing, and $$$$Z \rightarrow b \bar{b}$$$$ $Z\to b\overline{b}$ .

• Sponsoring Organization: USDOE
• Grant/Contract Number: SC0010504
• OSTI ID: 2370455
• Journal Information: European Physical Journal. C, Particles and Fields (Online), Journal Name: European Physical Journal. C, Particles and Fields (Online) Journal Issue: 6 Vol. 84; ISSN 1434-6052
• Publisher: Springer Science + Business MediaCopyright Statement
• Country of Publication: Germany
• Language: English