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Register a new user$B to rho l bar u$ and $omega l bar u$ in and beyond the Standard Model: Improved predictions and $|V_{ub}|$
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We revisit the experimental and theoretical status of $B to rho l bar{ u}$ and $B to omega l bar{ u}$ decays. We perform a combined fit of averaged spectra from Belle and Babar measurements with prior light cone sum rule calculations, in order to obtain more precise predictions over the full $q^2$ range. The extracted values of $|V_{ub}|$ from these combined fits exhibit smaller uncertainty compared to previous extractions from $B to rho l bar{ u}$ and $B to omega l bar{ u}$ decays and the central values are found to be smaller than values extracted from $B to pi l u$ or inclusive measurements. We use our fit results to obtain more precise predictions in and beyond the Standard Model for the lepton universality ratios $R(rho)$ and $R(omega)$, as well as several angular observables that are sensitive to the full $q^2$ distribution, such as the longitudinal polarization of the vector meson, the $tau$ polarization, and its forward-backward asymmetry.
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B --> rho l nu decay is analyzed in the effective theory of heavy quark with infinite mass limit. The matrix element relevant to the heavy to light vector meson semileptonic decays is parametrized by a set of four heavy flavor-spin independent universal wave functions at the leading order of effective theory. The form factors are calculated at the leading 1/m_Q order using the light cone sum rule method in the framework of effective theory. |V_{ub}| is then extracted via B --> rho l nu decay mode.
We analyze in detail the angular distributions in $bar{B}to D^*ell bar u$ decays, with a focus on lepton-flavour non-universality. We investigate the minimal number of angular observables that fully describes current and upcoming datasets, and explore their sensitivity to physics beyond the Standard Model (BSM) in the most general weak effective theory. We apply our findings to the current datasets, extract the non-redundant set of angular observables from the data, and compare to precise SM predictions that include lepton-flavour universality violating mass effects. Our analysis shows that the current presentation of the experimental data is not ideal and prohibits the extraction of the full set of relevant BSM parameters, since the number of independent angular observables that can be inferred from data is limited to only four. We uncover a $sim4sigma$ tension between data and predictions that is hidden in the redundant presentation of the Belle 2018 data on $bar{B}to D^*ell bar u$ decays. This tension specifically involves observables that probe $e-mu$ lepton-flavour universality. However, we find inconsistencies in these data, which renders results based on it suspicious. Nevertheless, we discuss which generic BSM scenarios could explain the tension, in the case that the inconsistencies do not affect the data materially. Our findings highlight that $e-mu$ non-universality in the SM, introduced by the finite muon mass, is already significant in a subset of angular observables with respect to the experimental precision.
In the heavy quark effective field theory of QCD, we analyze the order 1/m_Q contributions to heavy to light vector decays. Light cone sum rule method is applied with including the effects of 1/m_Q order corrections. We then extract |V_{ub}| from B -> rho l nu decay up to order of 1/m_Q corrections.
We calculate the contributions to the rare decays $B to X_{s,d} u bar u$ and $B_{s,d} to l^+l^-$ from one-loop $Z^0$-penguin diagrams in the framework of Topcolor-assisted Technicolor Model. Within the parameter space, we find that: (a) the new contribution from technipions is less than 2% of the standard model prediction; (b) the top-pions can provide a factor of 10 to 30 enhancement to the ratios in question; (c) the topcolor-assisted technicolor model is consistent with the current experimental data.
We calculate the contributions to the rare B-decays, $B to X_{s,d} u bar u$, $B_{s,d} to l^+l^- $ from the unit-charged technipions. Within the considered parameter space we find that: (a) the enhancements to the branching ratios in question can be as large as three orders of magnitude; (b) the ALEPH data of $B to X_s u bar u$ lead to strong mass bounds on $m_{p1}$ and $m_{p8}$: $m_{p8} geq 620, 475 GeV$ for $F_Q=40GeV$ and $m_{p1}=100, 400 GeV$ respectively. (c) the CDF data of $B_s to mu bar mu$ lead to a relatively weak limit: $m_{p8} geq 320 GeV$ for $F_Q=40GeV$ and $m_{p1}=200 GeV$.
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