Related papers: New physics effects in radiative leptonic $B_s$ de…

Deviations from the standard model prediction have been observed not only in $b \to c$ charged current interactions but also in $b \to s$ flavor changing neutral current interactions. In particular, the deviation observed in the measured…

Heavy quark decays provide a very advantageous investigation to test the Standard Model (SM). Recently, promising experiments with \textit{b} quark, as well as the analysis of the huge data sets produced at the B factories, have led to an…

In view of the recent and future electroweak precision data accumulated at LEP and SLC, we systematically analyze possible new physics effects that may occur in the leptonic sector within the context of $SU(2)_R \times SU(2)_L \times…

We study the radiative leptonic $D$ meson decays of $D^+_{(s)}\to \l^+\nu_{\l}\gamma$ ($\l=e,\mu,\tau$), $D^0\to \nu\bar{\nu}\gamma$ and $D^0\to \l^+\l^-\gamma$ ($l=e,\mu$) within the light front quark model. In the standard model, we find…

The recent measurement of $R_{K^*}$ is yet another hint of new physics (NP), and supports the idea that it is present in $b\to s\mu^+\mu^-$ decays. We perform a combined model-independent and model-dependent analysis in order to deduce…

Semileptonic decays provide an excellent environment for testing the Standard Model (SM). Violation of lepton universality would be a smoking gun for physics beyond the SM. Using semi-tauonic $B$ decays, LHCb finds a value of…

We combine our new results for the O(alpha_em) and O(alpha_s^2) corrections to B_{s,d} -> l^+ l^-, and present updated branching ratio predictions for these decays in the standard model. Inclusion of the new corrections removes major…

Recently, the LHC has found several anomalies in exclusive semileptonic b --> s l^+ l^- decays. In this proceeding, we summarize the most important results of our global analysis of the relevant decay modes. After a discussion of the…

We report a measurement of the branching fraction for the leptonic decay $B^+\to\mu^+\nu_\mu$. This work presents the first $B^+\to\mu^+\nu_\mu$ result using Belle~II data, an updated Belle measurement that supersedes the previous result,…

We analyze the $B\to K_2^*(\to K\pi)l^+l^-$ (with $l=e,\mu,\tau$) decay in the standard model and two new physics scenarios: vector-like quark model and family non-universal $Z'$ model. We derive its differential angular distributions,…

The apparent gap between the measured and the expected value for the semileptonic branching ratio of $B$ mesons has become more serious over the last year. This is due to the improved quality of the data and to the increasing maturity of…

The first search for nonresonant $B_c^+\to\pi^+\mu^+\mu^-$ decays is reported. The analysis uses proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb$^{-1}$.…

We study the semileptonic decays $B_s \to D_s^{(*)}\tau\bar{\nu}$ as a promising probe for new physics (NP) beyond the standard model (SM). The extension of the SM is done through the introduction of four-fermion operators beyond the $V-A$…

The phenomenon of $B^0_q-\bar B^0_q$ mixing ($q=d,s$) provides a sensitive probe for physics beyond the Standard Model. We explore the corresponding space for New Physics left through the current data, having a careful look at analyses of…

With respect to large samples of $B_c$ mesons expected to be produced at CERN Large Hadron Collider(LHC) and the large branching ratios $Br(B_{c}\to \tau\bar\nu)$ and $Br(B_{c}\to \mu\bar\nu)$, we suggest that $B_c$ purely leptonic decays…

At present, the measurements of some observables in $B \to K^* \mu^+\mu^-$ and $B_s^0 \to \phi \mu^+ \mu^-$ decays, and of $R_{K^{(*)}} \equiv {\cal B}(B \to K^{(*)} \mu^+ \mu^-)/{\cal B}(B \to K^{(*)} e^+ e^-)$, are in disagreement with…

We perform a model-independent analysis of the data on branching ratios and CP asymmetries of $B\to\phi K$ and $B\to\eta^{(')} K^{(*)}$ modes. The present data is encouraging to look for indirect evidences of physics beyond the Standard…

We investigate the angular decay distribution of the four-fold $B_{c}\to D^{\ast}_{s}(\to D_{s}\gamma)\mu^{+}\mu^{-}$, and $B_{c}\to D^{\ast}_{s}(\to D_{s}\pi)\mu^{+}\mu^{-}$ decays that proceed through $b\to s\mu^{+}\mu^{-}$ quark level…

It is experimentally observed that ratios of branching fractions for semitauonic and semileptonic $B$ decays, known as the $R(D^{(*)})$, are higher than Standard Model (SM) predictions. The $B \to \bar{D}^{(*)} \tau^{+} \nu_{\tau}$ decays,…

We investigate electromagnetic corrections to the rare $B$-meson leptonic decay $B_{s,d} \to \mu^+\mu^-$ from scales below the bottom-quark mass $m_b$. Contrary to QCD effects, which are entirely contained in the $B$-meson decay constant,…