Related papers: Semitauonic B Decay Anomaly
The $b \to c$ semileptonic sum rules provide relations between the decay rates of $B \to D^{(*)} \tau\bar\nu$ and $\Lambda_b \to \Lambda_c \tau\bar\nu$. Starting from the heavy quark and zero-recoil limits, we revisit the derivation of the…
Decays of the kind $B^0_{s,d}\to\ell^+\ell^-$ belong to the most favourable processes for probing the flavour structure of the Standard Model, with outstanding sensitivity to new (pseudo)-scalar contributions. While the branching ratio of…
The experimental prospects for precise measurements of the leptonic decays B_u -> tau nu / mu nu, B_s -> mu+ mu-, D -> mu nu and D_s -> mu nu / tau nu are very promising. Double ratios involving four of these decays can be defined in which…
We present a compressive study on rare semileptonic $B_c \to D^{(*)}\tau \bar \nu_\tau$ decays involving $b \to u \tau \bar \nu_\tau$ quark level transitions in an effective field theory approach. We consider the presence of an additional…
The BaBar Collaboration has recently reported the measurement of the ratio of the branching fractions of $\bar{B} \to D(D^{*}) \tau^{-} \bar{\nu_\tau}$ to $\bar{B} \to D(D^{*}) \ell^{-} \bar{\nu_\ell}$ which deviates from the Standard Model…
Recently, Belle II reported on the first measurement of $\mathcal{B}(B^\pm\to K^\pm \nu\bar{\nu})$ which appears to be almost $3\sigma$ larger than predicted in the Standard Model. We point out the important correlation with…
In the SU(3) symmetry limit, semileptonic $D^+\to Sl^+\nu$ and $B^-\to Sl^-\bar\nu$ decays, with $S=a_0(980)$, $f_0(980)$ and $f_0(600)$, are found to obey different sum rules in the $\bar qq$ and the tetra-quark descriptions for scalar…
We present a search for the decay B+ --> tau+ nu_tau using 467.8 x 10^6 B B-bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely…
BABAR and Belle measurements of branching fractions, rate asymmetries and angular observables in the decay modes B \to K(*)l+l- are reviewed and new results from CDF on B \to K(*){\mu}+{\mu}- branching fractions and angular observables are…
Considering the gluon condensate corrections, the form factors relevant to the semileptonic rare $B_c \rar D,D_s(J^{P}=0^{-}) l^{+}l^{-}$ with $l=\tau,\mu,e$ and $B_c \rar D,D_s(J^{P}=0^{-})\nu\bar{\nu}$ transitions are calculated in the…
Within the framework of HQET, $\Lambda_{b}\rightarrow\Lambda_{c}\tau\bar{\nu}_{\tau}$ and $\Omega_{b}\rightarrow\Omega_{c}^{(*)}\tau\bar{\nu}_{\tau}$ weak decays are studied to the order of $1/m_c$ and $1/m_b$. Helicity amplitudes are…
Recent LHCb measurements show small discrepancies with respect to the Standard Model (SM) predictions in selected angular distributions of the mode $B^0 \to K^{*0} \mu^+ \mu^-$. The possibility of explaining such tensions within theories…
Recent measurements of exclusive $B^{-} \to \tau^{-}\,\nu$ and $B^0 \to \pi^{+}\,l^{-}\,\bar{\nu}_l$ decays via the $b \to u\,l\,\nu$ transition process differ from the standard model expectation and, if they persist in future $B$…
Some long-standing problems in the experimental data for semileptonic b -> c l nu decay rates have resisted attempts to resolve them, despite substantial efforts. We summarize the issues, and propose a possible resolution, which may…
We study the four-body semileptonic baryonic decay of $B^-\to \Lambda\bar p\nu\bar \nu$ in the standard model. We find that the decay branching ratio is $(7.9\pm 1.9)\times 10^{-7}$. Similar to the rare decays of $B^-\to K^{(*)-}\nu\bar…
The LHCb measurements on the B ->$ K^*$$\mu^+ \mu^-$ angular observables have shown slight deviations from their Standard Model predictions. The significance of the deviations in the B -> $K^*$$\mu^+ \mu^-$ decay depends on the assumptions…
The latest standard model predictions of rare leptonic B_q --> l^+ l^- decays are reviewed including recent results of next-to-leading electroweak and next-to-next-to-leading QCD corrections.
We study the decays of $B\to K^{(*)} \ell^{+} \ell^{-}$ in split supersymmetry with R-parity violation. We find that the decay branching ratio of $B\to K\tau^+\tau^-$ in the new physics model due to the scalar interactions can be $1.8\times…
We study the exclusive semileptonic rare $B_c^+ \to D^+ \nu \bar{\nu}$ decay in the framework of light-cone quark model. The transition form factors $f_{+}(q^2)$ and $f_{T}(q^2)$ are evaluated in the time-like region using the analytic…
We discuss rare meson decays $K^ + \to \pi ^ - \ell ^ + \ell '^ + $ and $D^ + \to K^ - \ell ^ + \ell '^ +$ ($\ell, \ell'=e, \mu$) in a supersymmetric extension of the Standard Model with R-parity violation. Estimates of the branching ratios…