3 years ago

$b \to c \ell \nu$ anomalies in light of extended scalar sectors.

Avirup Shaw, Sunando Kumar Patra, Aritra Biswas, Dilip Kumar Ghosh

In view of the recent experimental results on exclusive semileptonic $B$ meson decays showing sizable departure from Standard Model prediction of lepton flavor universality, and keeping ongoing and proposed non-standard Higgs searches in mind, we explore the charged current heavy flavor observables ($\mathcal{R}_{D^{(*)}}$, $\mathcal{R}_{J/\psi}$), among other $b\to c\ell \nu$ transitions, in the presence of a relevant scalar current effective new physics operator. We do this under the constraints of the $B_c$ lifetime and predicted bounds on the branching fraction of $B_c \to \tau \nu$ decay. We show the allowed parameter space in terms of the real and imaginary parts of the corresponding Wilson coefficients for such interactions. Under the light of obtained results, we look into the prospect of two classes of models, rendering the Wilson coefficients real and complex respectively. We use two new physics models: (a) the Georgi-Machacek (GM) model, and (b) one Leptoquark (LQ) scenario. While there have been several heavy flavor analyses on possible LQ models till date, semileptonic $B$ decays have never been studied in the GM model to the best of our knowledge. We show that constraints from $b\to c\ell \nu$ on GM parameters are consistent with other flavor constraints on the model if we drop the Babar results. Including those disfavors the model by more than $3\sigma$. On the other hand, one benchmark LQ scenario, which gives rise to a single scalar current effective interaction, is still allowed within $68\%$ confidence level, albeit with a shrunk parameter space.

Publisher URL: http://arxiv.org/abs/1801.03375

DOI: arXiv:1801.03375v1

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