相关论文: Understanding the first measurement of $\mathcal{B…
We report the observation of the decay $B^{\pm} \to \phi \phi K^{\pm}$ and find evidence for $B^{0} \to \phi \phi K^{0}$. These results are based on a 414 fb$^{-1}$ data sample that contains $449 \times 10^6$ $B\bar{B}$ pairs, collected…
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…
B physics has played a prominent role in investigations of new physics effects at low-energies. Presently, the largest discrepancy between a standard model prediction and experimental measurements appears in the branching ratio of the…
LHCb found hints for physics beyond the Standard Model (SM) in $B\to K^*\mu^+\mu^-$, $R(K)$ and $B_s\to\phi\mu^+\mu^-$. These intriguing hints for NP have recently been confirmed by the LHCb measurement of $R(K^*)$ giving a combined…
Semileptonic $b\to c\tau\bar{\nu}_{\tau}$ decays are powerful probes of non-Standard-Model effects within an effective-field-theory (EFT) framework, but fully exploiting them in current and future data demands combinations that maximise…
We analyze possible new physics (NP) effects on $b\to s$ transition processes, $R(K^{(*)})$, $B_s\to\mu^+\mu^-$, and $B^+\to K^+\nu{\bar\nu}$ decays. Though recent data for $R(K^{(*)})$ and ${\rm Br}(B_s\to\mu^+\mu^-)$ are compatible with…
The latest BaBar measurements of the ratios ${\cal R}(D^{(*)})=\displaystyle{\frac{{\cal B}(B \to D^{(*)} \tau {\bar \nu}_\tau)}{{\cal B}(B \to D^{(*)} \mu {\bar \nu}_\mu)}}$ deviate from the Standard Model predictions at the global level…
We report a measurement of the branching fraction of $B^+ \to \tau^+ \nu_\tau$ decays using a data sample of $772 \times 10^6 B \bar{B}$ pairs, collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy…
We report the first measurement of the $\tau$ lepton polarization $P_\tau(D^*)$ in the decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = \mathcal{B}(\bar…
The rare decays B_s -> \mu^+\mu^- and B -> K^{(*)}\mu^+\mu^- are sensitive to new particles and couplings via their interferences with the standard model contributions. Recently, the upper bound on B(B_s -> \mu^+\mu^-) has been improved…
We report the first measurement of the $\tau$ lepton polarization in the decay ${\bar B} \rightarrow D^* \tau^- {\bar\nu_{\tau}}$ as well as a new measurement of the ratio of the branching fractions $R(D^{*}) = \mathcal{B}({\bar B}…
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…
The most recent measurements of the observables $R_{D^{(*)}}$ are in tension with the Standard Model offering hints of New Physics in $b\rightarrow c \ell \bar{\nu}_{\ell}$ transitions. Motivated by these results, in this work we present an…
We examine the $q^2$-binned distributions of the $D\to K\mu\nu$ decay rate and of the corresponding forward-backward asymmetry which were recently measured by BESIII, showing a mild deviation from the Standard Model predictions. We point…
The following is an overview of the measurements of the CKM matrix elements V_cb and V_ub that are based on detailed studies of semileptonic B decays by the BABAR and Belle Collaborations and recent advances in QCD calculations. In…
Recently, \texttt{Belle II} announced evidence for the decay $B^+\to K^+ +\nu +\bar{\nu}$ at the $3.5\,\sigma$ significance, and measured the corresponding decay branching ratio to be $2.7\,\sigma$ above the Standard Model prediction. Here,…
The rare four-fold decay $B_s \to K^*(\to K\pi)\mu^+\mu^- $, governed by the flavor-changing neutral current transition $b \to d\mu^+\mu^-$, provides a sensitive probe for testing the Standard Model (SM) and investigating signatures of new…
Implications of the recent new measurements of $B\to K_1\gamma$ by Belle are examined. It is shown that the new branching ratio $\calB(B\to K_1(1270)\gamma)$ requires very large form factor compared to the theoretically predicted one. This…
The Belle Collaboration has recently measured the complete set of angular coefficient functions for the exclusive decays $\bar B \to D^* (D \pi) \ell \bar \nu_\ell$, with $\ell=e,\,\mu$, in four bins of the parameter…
We report an observation of the decay $B^0\to D^{*-} \tau^+ \nu_{\tau}$ in a data sample containing $535\times10^6$ $B\bar{B}$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We find a signal with a…