相关论文: Remarks on the Standard Model predictions for $R(D…

The decays $B_c^+ \to B_{a} \bar \ell \nu_\ell$ and $B_c^+ \to B_{a}^{*}(\to B_a \gamma) \bar \ell \nu_\ell$, with $a=s,d$ and $\ell=e,\mu$, are studied in the Standard Model (SM) and in the extension based on the low-energy Hamiltonian…

Form factors are crucial theory input in order to extract $|V_{cb}|$ from $B \to D^{(*)}\ell\nu$ decays, to calculate the Standard Model prediction for ${\cal R}(D^{(*)})$ and to assess the impact of New Physics. In this context, the…

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…

The reported combined excess of about 4$\sigma$, by BABAR, Belle and LHCb, in the measurements of R($D^{(*)}$) and Br(B $\rightarrow \tau \nu_{\tau}$) from that of the standard model expectation constitute the most significant discrepancy…

In the Standard Model of particle physics, charged leptons of different flavour couple to the electroweak force carriers with the same interaction strength. This property, known as lepton flavour universality, was found to be consistent…

Tension between the Standard Model (SM) and data concerning $b \rightarrow s$ processes has become apparent. Most notoriously, concerning the $R_K$ ratio, which probes lepton non-universality in $b$ decays, and measurements involving the…

We report a measurement of the ratios of branching fractions $\mathcal{R}(D^{(*)}) = {\cal B}(\bar{B} \to D^{(*)} \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B} \to D^{(*)} \ell^- \bar{\nu}_{\ell})$ where $\ell$ denotes an electron or a muon.…

With the potential prospects of the $D^{*}_{s}$ at high-luminosity heavy-flavor experiments in the future, we investigated the CKM-favored and tree-dominated leptonic $D^{*}_{s}\to\ell\bar{\nu}_{\ell}$ and semileptonic $D^{*}_{s}\to…

Experimental measurements collected by the BABAR, Belle, and LHCb experiments on different observables associated with the semileptonic transition $b \to c \tau \bar{\nu}_\tau$, indicate the existence of disagreement respect with the…

In a general framework, valid for any $H\to H'\ell^-\bar\nu_\ell$ semileptonic decay, we analyze the $d^2\Gamma/(d\omega d\cos\theta_\ell)$ and $d^2\Gamma/ (d\omega dE_\ell)$ distributions, with $\omega$ being the product of the hadron…

We apply the general formalism derived in N. Penalva et al. [Phys. Rev. D 101, 113004 (2020)] to the semileptonic decay of pseudoscalar mesons containing a $b$ quark. While present $B\to D^{(*)}$ data give the strongest evidence in favor of…

In recent times, several hints of lepton non-universality have been observed in semileptonic $B$ meson decays, both in the charged-current ($b \to c l \bar \nu_l$) and neutral-current ($b \to s ll $) transitions. Motivated by these…

The semitauonic decay $\bar{B} \rightarrow D^* \tau^- \bar{\nu}_\tau$ is sensitive to new physics beyond the Standard Model (SM) that has an enhanced coupling to the $\tau$ lepton. In the ratio of branching fractions $R(D^*) =…

The persistent deviations observed in semileptonic $B$ decays, in particular the lepton flavor universality ratios $\mathcal{R}(D^{(*)})$ and $\mathcal{R}(\Lambda_c)$, provide intriguing hints of physics beyond the Standard Model (SM).…

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,…

Experimental measurements of $R_{D}$, $R_{D^*}$ and $R_{J/\Psi}$ in $B \to (D,\,D^{\ast})l\nu$ and $B_c \to J/\Psi l \nu$ decays mediated via $b \to c\,l\,\nu$ charged current interactions deviate from standard model prediction by…

At the back of succeeding measurements of anomalies in semileptonic decays at LHCb and several collider experiments hinting at the possible violation of lepton flavor universality, we undertake a concise review of theoretical foundations of…

In this paper, we analyze different decay observables of semileptonic $ B_c$ decays into $(D_(s,d)^((*))){\mu}^+ {\mu}^-$ such as branching ratio, forward-backward asymmetry, polarization fraction and lepton polarization asymmetry in the…

Recently, several $B$-physics experiments have reported an appreciable deviation from the Standard Model (SM) in the tree-level observables $R_{D^{(*)}}$; the combined weighted average now stands at $\approx 4 \sigma$. We first show the…

In this addendum to arXiv:1811.09603 we update our results including the recent measurement of ${\cal R}(D)$ and ${\cal R}(D^*)$ by the Belle collaboration: ${\cal R}(D)_{\rm Belle} = 0.307\pm0.037\pm0.016$ and ${\cal R}(D^*)_{\rm…