Related papers: $b \to c$ semileptonic sum rule: Extension to angu…
I discuss recent progress in lattice calculations of $B \to D^{(*)} \ell \nu$ form factors, important for the precision determination of $|V_{cb}|$ in the Standard Model (SM), and for testing SM expectations of lepton flavor universality in…
There is a wide class of models which give a dynamical description of the origin of flavour in terms of spontaneous symmetry breaking of an underlying symmetry. Many of these models exhibit sum rules which relate on the one hand mixing…
We measure the complete set of angular coefficients $J_i$ for exclusive $\bar{B} \to D^* \ell \bar{\nu}_\ell$ decays ($\ell = e, \mu$). Our analysis uses the full $711\,\mathrm{fb}^{-1}$ Belle data set with hadronic tag-side reconstruction.…
We present the first comprehensive tests of light-lepton universality in the angular distributions of semileptonic $B^0$-meson decays to charged spin-1 charmed mesons. We measure five angular-asymmetry observables as functions of the decay…
We perform a detailed analysis of the semileptonic $\Xi_b\rightarrow \Xi_c \ell^- \bar{\nu}_\ell$ decays within the perturbative QCD framework. In our study, the $\Xi_b\rightarrow \Xi_c$ transition form factors are calculated using several…
We present a sum rule relating the electron energy spectrum and the hadron mass distribution in semileptonic b -> u decays close to threshold. The relation found is free from non-perturbative effects and the theoretical error is expected to…
We present a consistent analysis of $\Upsilon$ sum rules and $B$-meson semileptonic width in the next-to-next-to-leading order in the strong coupling constant. The analysis is based on the analytical result for the heavy quark vector…
We study the semileptonic transitions B_c to \eta_c, J/\psi, D, D^*, B, B^*, B_s, B_s^* in the framework of a relativistic constituent quark model. We use experimental data on leptonic J/\psi decay, lattice and QCD sum rule results on…
The flavor-changing neutral current decays of heavy bottom quark, alongside the flavor-changing charged current processes mediated by $b \to (c, u)$ in semileptonic $B$ decays are emerged as powerful tools for exploring physics beyond the…
Besides being important to determine Standard Model parameters such as the CKM matrix elements $|V_{cb}|$ and $|V_{ub}|$, semileptonic $B$ decays seem also promising to reveal new physics (NP) phenomena, in particular in connection with the…
Recent experimental progress on baryonic rare decays has spurred a deeper investigation on flavor-changing neutral current transitions in the baryon sector. Within the framework of QCD sum rules, we derive a complete set of form factors for…
Motivated by the recent observation of lepton universality violation in the flavour changing charged current transitions $b \to c l \bar{\nu}_l$, we intend to scrutinize the lepton non-universality effects in rare semileptonic $B$ meson…
The measured $\bar{B}\to D^{(*)} l \bar\nu$ decay rates for light leptons ($l=e,\mu$) constrain all $\bar{B}\to D^{(*)}$ semileptonic form factors, by including both the leading and ${\cal O}(\Lambda_{\text{QCD}}/m_{c,b})$ subleading…
The study of lepton flavor universality violation (LFUV) in semitauonic $b$-hadron decays has become increasingly important in light of longstanding anomalies in their measured branching fractions, and the very large datasets anticipated…
We underline a problem existing in the heavy quark limit of QCD concerning the rates of semileptonic B decays into P-wave $D_J(j)$ mesons, where $j = {1 \over 2}$ (wide states) or $j = {3 \over 2}$ (narrow states). The leading order sum…
A new method to extract $|V_{\rm bc}|$ is proposed based on a sum--rule for semileptonic decays of the $B$ meson. The method relies on much weaker assumptions than previous approaches which are based on heavy--quark symmetry. This sum--rule…
The Standard Model (SM) of particle physics was finalized in its current form in the mid-1970s, and has been extensively tested and confirmed ever since, with the discovery of the Higgs boson in 2012 being the last missing piece. While no…
We present an analysis of semileptonic decays of orbitally, $P$-wave excited $B_{s}$ meson states $B^{**}_{s}$, including the newly found narrow $B_{s1}(5830)$ and $B^{*}_{s2}(5840)$ states, into low lying $D_{s}$ mesons ($D_{s}(1968)$,…
We analyse the new physics implications of theoretically clean $b \to s$ observables in a model-independent approach and compare their coherence with the implications of other rare $B$-decays. A statistical comparison is done between the…
Present measurements of b->c tau nu and b->u tau nu transitions differ from the standard model predictions of lepton flavor universality by almost 4sigma. We examine new physics interpretations of this anomaly. An effective field theory…