arXiv subjects

Sunando K. Patra

Publications and source records attributed to Sunando K. Patra.

2 recordsLinked to original sources

arXiv2017

Looking for possible new physics in $B\to D^{(\ast)}τν_τ$ in light of recent data

We study the decays $B\to D^{(\ast)}τν_τ$ in light of the available data from BABAR, Belle and LHCb. We divide our analysis into two parts: in one part we fit the form-factors in these decays directly from the data without adding any additional new physics (NP) contributions and compare our fit results with those available from the decays $B\to D^{(\ast)}\ellν_{\ell}$. We find that the $q^2$-distributions of the form-factors associated with the pseudo-vector current, obtained from $B\to D^{(\ast)}τν_τ$ and $B\to D^{(\ast)}\ellν_{\ell}$ respectively, do not agree with each other, whereas the other form-factors are consistent with each other. In the next part of our analysis, we look for possible new effective operators of dimension 6 amongst new vector, scalar, and tensor-type that can best explain the current data in the decays $B\to D^{(\ast)}τν_τ$. We use the information-theoretic approaches, especially of `Second-order Akaike Information Criterion' (AIC$_c$) in the analysis of empirical data. Normality tests for the distribution of residuals are done after selecting the best possible scenarios, for cross-validation. We find that it is the contribution from the operator involving left or right-handed vector current that passes all the selection criteria defined for the best-fit scenario and can successfully accommodate all the available data set.

hep-ph↗

arXiv2016

Correlating new physics signals in $B \to D^{(*)} τν_τ$ with $B \to τν_τ$

Semileptonic and purely leptonic decays of B meson to $τ$, such as $B\to D^{(\ast)}τν_τ$ and $B\toτν_τ$ are studied. Recognizing that there already were some weak hints of possible deviations from the SM in the measurements of $\mathcal{B}(B\toτν_τ)$ by \Babar~and Belle and the fact that detection of the $τ$ also occurs in the measurements of $B\to D^{(\ast)}τν_τ$, we stress the importance of joint studies of these processes, whenever possible. For this purpose, as an illustration, we introduce the observable, $\mathcal{R}(D^{(*)})/\mathcal{B}(B\toτν_τ)$ where, for one thing, the unknown systematics due to $τ$ identification are expected to largely cancel. We show that all measurements of this observable are consistent with the existing data, within somewhat largish experimental errors, with the predictions of the SM. We stress that precise experimental measurement and comparison with theory of the branching ratio for $B \to τν_τ$ is extremely important for a reliable search of new physics. Furthermore, in view of the anticipated improved precision in experiments in the next few years, in addition to $\mathcal{R}(D^{(*)})$, host of other ratios analogous to $\mathcal{R}(D^{(*)})/\mathcal{B}(B \to τν_τ)$ in the SM are suggested for lattice calculations as well, so that for more stringent tests of the SM, correlations in lattice calculations can be properly taken into account to enhance precision.

hep-ph↗