Related papers: Probing Lepton Universality with (Semi)-Leptonic B…
We study the semileptonic decay $\bar{B}_s \to K^{*+} \ell^-\bar\nu_\ell$, which is induced by $b\to u \ell^- \bar\nu_\ell$ transitions at the quark level. We take into account the standard model (SM) operator from $W$-boson exchange as…
Semileptonic flavor changing neutral current transitions with a pair of neutrinos in the final state are very accurately determined in the standard model (SM) and thus provide an accurate and sensitive probe for physics beyond the SM. Until…
Three recent measurements of leptonic and semileptonic decays of $B$ mesons are presented here. All results use the full Belle II Run 1 $e^+e^- \to \Upsilon(4S) \to B\bar{B}$ dataset of 365 fb$^{-1}$. We present one leptonic $B$ decay…
We report a measurement of the ratio ${\cal R}(D^*) = {\cal B}(\bar{B}^0 \rightarrow D^{*+} \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B}^0 \rightarrow D^{*+} \ell^- \bar{\nu}_{\ell})$, where $\ell$ denotes an electron or a muon. The results…
We study semileptonic decays $B^\pm \to \eta^{(\prime)} l \nu$, which are suggested to be used to extract the hadronic form factors of $B$ meson decays to $\eta(\eta^{\prime})$ and the angle of $\eta-\eta^{\prime}$ mixing. This would be of…
One of the fundamental predictions of the Standard Model is Lepton Flavour Universality. Any deviation from this prediction would indicate the existence of physics beyond the Standard Model. Recent LHCb measurements present a pattern of…
The study of $\bar{B} \to D^* \tau {\bar{\nu}}_\tau$ angular distribution can be used to obtain information about new physics (or beyond the Standard Model) couplings, which are motivated by various $B$ anomalies. However, the inability to…
We present a study of B decays into semileptonic final states containing charged and neutral $D_1(2420)$ and $D_2^*(2460)$. The analysis is based on a data sample of $208 fb^{-1}$ collected at the $\Upsilon(4S)$ resonance with the BaBar…
Leptoquark models are prime candidates for new physics (NP) explanations of the long-standing anomalies in semi-leptonic $B$ decays; $b\to c \tau \bar\nu$ (encoded in $R(D^{(\ast)})$) and $b\to s\ell\bar\ell (\ell=e,\mu)$ transitions.…
We review the physics of purely leptonic decays of $\pi^\pm$, $K^\pm$, $D^{\pm}$, $D_s^\pm$, and $B^\pm$ pseudoscalar mesons. The measured decay rates are related to the product of the relevant weak-interaction-based CKM matrix element of…
We address the recent anomalies in semi-leptonic $B$-meson decays using a model of fermion masses based on the $U(2)$ flavor symmetry. The new contributions to $b \to s \ell \ell$ transitions arise due to a tree-level exchange of a…
Motivated by recent results from the LHCb, BABAR and Belle collaborations on B\to D^{(*)}\ell^-\bar{\nu}_\ell decays, which significantly deviate from the Standard Model and hint the possible new physics beyond the Standard Model, we probe…
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 results on the ratios of branching fractions $\mathcal{R}(D) = {\cal B}(\bar{B} \to D \tau^- \bar{\nu}_{\tau})/{\cal B}(\bar{B} \to D \ell^- \bar{\nu}_{\ell})$ and $\mathcal{R}(D^*) = {\cal B}(\bar{B} \to D^* \tau^-…
Non-leptonic $B^0_s \rightarrow D_s^{\pm} K^{\mp}$ transitions are particularly interesting processes to test the Standard Model. As these decays occur via pure tree diagrams, they allow a theoretically clean determination of the angle…
We review the physics of purely leptonic decays of $\pi^\pm$, $K^\pm$, $D^{\pm}$, $D_s^\pm$, and $B^\pm$ pseudoscalar mesons. The measured decay rates are related to the product of the relevant weak-interaction-based CKM matrix element of…
We measure partial branching fractions for the inclusive charmless semileptonic decay of $\Bxulnu$, and present determinations of the CKM matrix element $\Vub$. This analysis is based on a sample of 467 million $\FourS$ decays into $\BB$…
Semileptonic $b$-hadron decays proceed via charged-current interactions and provide powerful probes for testing the Standard Model and searching for New Physics effects. The advantages of studying such decays include the large branching…
The flavor changing decays of heavy bottom quarks to the corresponding lighter quarks ($u$, $c$ and $s$) in various $B$-meson decays via charged current and neutral current semileptonic transitions have emerged as promising candidates to…
The rare B_s-> \phi \ell^+ \ell^- decay is investigated by using the most general model independent effective Hamiltonian for $\ell= \mu, \tau$. The calculated $Br(B_s \rar \phi \mu^+ \mu^-) = 1.92 \times 10^{-6}$ is in consistent with the…