Investigating the effect of $U_1$ vector leptoquark on $b\to u\tau \bar{\nu }$ mediated $B$ decays

Abstract

The recent measurements of lepton flavor university (LFU) violating observables in semileptonic $b\to c\ell \bar{\nu }$ and $b\to s{\ell }^{+}{\ell }^{-}$ transitions by various experiments exhibit $(2-3)\sigma$ deviations from their corresponding Standard Model (SM) predictions. These tantalizing signals hint towards the possible role of new physics (NP) in $b\to c\tau \bar{\nu }$ and $b\to s{\mu }^{+}{\mu }^{-}$ decay channels. This in turn indicates that the same class of NP as appeared in $b\to c\tau \bar{\nu }$, might also show up in other tree level processes involving $b\to u\tau \bar{\nu }$ transition. Since these charged current transitions are doubly Cabibbo suppressed, the NP contributions could be significant enough leading to sizeable effects in some of the observables. In this paper, we study the implications of the vector leptoquark $U_1(3,1,2/3)$, which is one of the few scenarios that can simultaneously explain the LFU violation signals both in the charged-current as well as neutral-current sectors, on the semileptonic decays $B\to (\pi ,\rho ,\omega )\tau \bar{\nu }$ and $B_s\to (K,K^{\ast })\tau \bar{\nu }$. In particular, we pay our attention to the branching fraction, lepton flavor non-universality (LNU) observable, forward-backward asymmetry and the polarization asymmetry parameters of these modes. We find substantial deviations in the branching fractions as well as LNU observables of these decay modes due to the $U_1$ contributions, which can be probed by the currently running experiments LHCb and Belle-II.

arXiv comment23 pages, 6 figures

References in corpus (37)

• Measurement of the branching ratio of $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ relative to $\bar{B}\to D^{(\ast )}{\ell }^{-}{\bar{\nu }}_{\ell }$ decays with hadronic tagging at Belle
• $B\to V{\ell }^{+}{\ell }^{-}$ in the Standard Model from Light-Cone Sum Rules
• One Leptoquark to Rule Them All: A Minimal Explanation for $R_{D^{(\ast )}}$, $R_K$ and $(g-2{)}_{\mu }$
• Measurement of the $\tau$ lepton polarization and $R(D^{\ast })$ in the decay $\bar{B}\to D^{\ast }{\tau }^{-}{\bar{\nu }}_{\tau }$
• Vector leptoquark resolution of $R_K$ and $R_{D^{(\ast )}}$ puzzles
• Testing leptoquark models in $\bar{B}\to D^{(\ast )}\tau \bar{\nu }$
• The lifetime of the $B_c^{-}$ meson and the anomalies in $B\to D^{(\ast )}\tau \nu$
• A model of vector leptoquarks in view of the $B$-physics anomalies
• B-decay discrepancies after Moriond 2019
• Baryon Number and Lepton Universality Violation in Leptoquark and Diquark Models
• Lattice QCD calculation of form factors describing the rare decays $B\to K^{\ast }{\ell }^{+}{\ell }^{-}$ and $B_s\to \varphi {\ell }^{+}{\ell }^{-}$
• Leptoquark model to explain the $B$-physics anomalies, $R_K$ and $R_D$
• Importance of Loop Effects in Explaining the Accumulated Evidence for New Physics in B Decays with a Vector Leptoquark
• Emerging patterns of New Physics with and without Lepton Flavour Universal contributions
• New Physics in $b\to s{\ell }^{+}{\ell }^{-}$ confronts new data on Lepton Universality
• Global fit to $b\to c\tau \nu$ transitions
• Excesses of muon $g-2$, $R_{D^{(\ast )}}$, and $R_K$ in a leptoquark model
• Revisiting the vector leptoquark explanation of the B-physics anomalies
• Continuing search for new physics in $b\to s\mu \mu$ decays: two operators at a time
• Left-Right SU(4) Vector Leptoquark Model for Flavor Anomalies
• Update on the b->s anomalies
• Addendum to "Impact of polarization observables and $B_c\to \tau \nu$ on new physics explanations of the $b\to c\tau \nu$ anomaly"
• Explaining the $R_K$ and $R_{D^{(\ast )}}$ anomalies with vector leptoquarks
• Composite Leptoquarks at the LHC
• Inclusive search for a highly boosted Higgs boson decaying to a bottom quark-antiquark pair
• Revisiting the new-physics interpretation of the $b\to c\tau \nu$ data
• D* polarization as a probe to discriminate new physics in B --> D* tau nubar
• Implications for New Physics in $b\to s\mu \mu$ transitions after recent measurements by Belle and LHCb
• \large\bf $B_c\to (J/\Psi ,{\eta }_c)\tau \nu$ semileptonic decays within Standard model and beyond
• $b\to c\tau {\nu }_{\tau }$ Decays: A Catalogue to Compare, Constrain, and Correlate New Physics Effects
• $b\to c\tau \nu$ Transitions in the Standard Model Effective Field Theory
• Solutions to $R_D$-$R_{D^{\ast }}$ in light of Belle 2019 data
• Probing New Physics with $\bar{B}\to \rho (770){\ell }^{-}{\bar{\nu }}_{\ell }$ and $\bar{B}\to a_1(1260){\ell }^{-}{\bar{\nu }}_{\ell }$
• Maximizing the Impact of New Physics in $b\to c\tau \nu$ Anomalies
• Search for $B^0\to {\pi }^{-}{\tau }^{+}{\nu }_{\tau }$ with hadronic tagging at Belle
• New physics in $b\to s{e}^{+}{e}^{-}$?
• Impact of vector new physics couplings on $B_s\to (K,K^{\ast })\tau \nu$ and $B\to \pi \tau \nu$ decays

Cited by in corpus (3)

• Precise limits on the charge-$2/3$ $U_1$ vector leptoquark
• Impact of $b\to c$ measurements on ${\Lambda }_b\to p\tau \bar{\nu }$ decay in $U_1$ leptoquark model
• Exploring the role of new physics in $b\to u\tau \bar{\nu }$ decays