相关论文: $R_{D^*}$ or $R_{D\pi}$: closing the theoretical g…

In the Standard Model, lepton universality refers to the identical electroweak gauge interactions among charged leptons. The measurement of the branching ratio $R_{e / \mu} = \frac{\Gamma(\pi\rightarrow\ e…

The cusp effect in K \to 3\pi and data on K_e4 decays allow one to extract experimental information on the elastic \pi\pi scattering amplitude near threshold, and to confront the outcome of the analyses with predictions made in the…

The $K_L \to \pi^0 \nu \bar\nu$ decay is analyzed in a model independent way. When lepton flavor is conserved, this decay mode is a manifestation of CP violating interference between mixing and decay. Consequently, a theoretically clean…

Recent measurements of semileptonic B-meson decays seemingly imply violations of lepton flavor universality beyond the Standard Model predictions. With three-level explanations based on extended Higgs sectors being strongly challenged by…

The experimental values of the lepton-flavour-universality tests ${\cal R}(D)$ and ${\cal R}(D^*)$ show a tension of about $3.1\sigma$ with their Standard Model prediction. Motivated by this tension, we perform a fit of the $b\to c\tau\nu$…

In this work, we have conducted a comprehensive and systematic theoretical investigation of the full cascade decays of charged pseudoscalar mesons, specifically $D_s$, $D$, $B$, and $B_c$, into $\tau \nu_\tau$, followed by the subsequent…

We derive compact expressions for the helicity amplitudes of the many-body $B \to D^{(*)}(\to DY)\tau(\to X\nu)\nu$ decays, specifically for $X = \ell \nu$ or $\pi$ and $Y = \pi$ or $\gamma$. We include contributions from all ten possible…

The impact of new and highly precise neutron \b{eta} decay data is reviewed. We focus on recent results from neutron lifetime, \b{eta} asymmetry, and electron-neutrino correlation experiments. From these results, weak interaction parameters…

The Standard Model predicts a large width difference in the $B_s$ system. New physics can contribute significantly to the {\it mass} difference. If this contribution is CP violating, this will always result in a reduction of the {\it width}…

Exploiting $B$-meson decays for Standard Model tests and beyond requires a precise understanding of the strong final-state interactions that can be provided model-independently by means of dispersion theory. This formalism allows one to…

Recently hints of lepton flavor non-universality emerged when the BaBar Collaboration observed deviations from the standard model predictions in $R(D^{(*)}) \equiv {\cal B}({\bar B} \to D^{(*)+} \tau^- {\bar\nu}_\tau) / {\cal B}({\bar B}…

The di-leptons and di-neutrinos observed in the final states of flavor-changing neutral b decays provide an ideal platform for probing physics beyond the standard model. Although the latest measurements of $R_{K^{(*)}}$ agree well with the…

I review the current status of measurements involving semi-tauonic $B$ meson decay at the $B$-factories. I briefly discuss the experimental methods and highlight the importance of background contributions especially from poorly understood…

We study possible new physics (NP) effects on $B_c \to J/\psi \tau\bar\nu$, which has been recently measured at LHCb as the ratio of $R_{J/\psi} = \mathcal B(B_c \to J/\psi \tau\bar\nu)/\mathcal B(B_c \to J/\psi \mu\bar\nu)$. Combining it…

At the present time, there are a number of measurements of $B$-decay observables that disagree with the predictions of the standard model. These discrepancies have been seen in processes governed by two types of decay: (i) $b \to s \mu^+…

I present a new formalism of the R-matrix theory where the formal parameters for the resonance energies and widths are identical to the observed values. By allowing the boundary condition parameters to vary from level to level, the freedom…

The color-suppressed \bar B^0-> D^{(*)0}\pi^0, D^{(*)0}\eta, D^0\omega decay modes have just been observed for the first time. The rates are all larger than expected, hinting at the presence of final state interactions. Considering \bar…

The recently observed direct CP violation in $B_d \to K^+ \pi^-$ has raised suggestions of possible new physics. A robust test of the standard model vs. new physics is its prediction of equal direct CP violation in $B_s \to K^- \pi^+$…

In this talk, an overview of the latest $R(D^{(*)})$ measurements performed at the Belle and LHCb experiments is presented. The main approach and methodology of each measurement is discussed, along with the current limitations and potential…

Deviations from the standard model predictions have been reported in various observables concerned with the lepton flavor universality. At present, the deviation of the measured values of $R_D$ and $R_{D^{\ast}}$ from the standard model…