We study the radiative $B\ensuremath{\rightarrow}K{\ensuremath{\eta}}^{(\ensuremath{'})}\ensuremath{\gamma}$ decays, which are important to investigate $CP$ violation, and are also relevant to assess the role of the exclusive modes induced by the $b\ensuremath{\rightarrow}s\ensuremath{\gamma}$ transition to saturate the inclusive $B\ensuremath{\rightarrow}{X}_{s}\ensuremath{\gamma}$ decay rate. Moreover, these channels do not display the same hierarchy as $B\ensuremath{\rightarrow}K{\ensuremath{\eta}}^{(\ensuremath{'})}$ modes, for which the decay into ${\ensuremath{\eta}}^{\ensuremath{'}}$ is enhanced with respect to one into $\ensuremath{\eta}$. The three-body radiative decays reverse the role: we find that this experimentally observed behavior (although affected by a large uncertainty in the case of the ${\ensuremath{\eta}}^{\ensuremath{'}}$) is reproduced in the theoretical analysis. We compute a ${B}^{*}\ensuremath{\rightarrow}K$ form factor, needed for this study, using light cone QCD sum rules, and discuss a relation expected to hold in the large energy limit for the light meson. Finally, we examine $B\ensuremath{\rightarrow}K\ensuremath{\eta}\ensuremath{\gamma}$ in two extensions of the standard model with universal extra dimensions, to investigate the sensitivity of this rare mode to such a kind of new physics effects.
The BABAR measurements of the ratios $\mathcal{R}({D}^{(*)})=\frac{\mathcal{B}(B\ensuremath{\rightarrow}{D}^{(*)}\ensuremath{\tau}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}})}{\mathcal{B}(B\ensuremath{\rightarrow}{D}^{(*)}\ensuremath{\mu}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}})}$ deviate from the standard model expectation, while new results on the purely leptonic $B\ensuremath{\rightarrow}\ensuremath{\tau}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ mode show a better consistency with the standard model, within the uncertainties. In a new physics scenario, one possibility to accommodate these two experimental facts consists in considering an additional tensor operator in the effective weak Hamiltonian. We study the effects of such an operator in a set of observables, in semileptonic $B\ensuremath{\rightarrow}{D}^{(*)}$ modes as well as in semileptonic $B$ and ${B}_{s}$ decays to excited positive-parity charmed mesons.
Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Pietro Biancofiore; Rare B(s) decays in the standard model and in a scenario with two universal extra dimensions. AIP Conf. Proc. 23 October 2012; 1492 (1): 113–116. https://doi.org/10.1063/1.4763502 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search
We study a set of exclusive $$B$$ and $$B_s$$ decay modes induced by the rare $$b \rightarrow s \nu \bar{\nu }$$ transition in the RS $$_c$$ model, an extra-dimensional extension of the standard model with warped 5D metric and extended gauge group. We discuss the role of correlations among the observables, and their importance for detecting the predicted small deviations from the standard model expectations.
Recent LHCb measurements show small discrepancies with respect to the Standard Model (SM) predictions in selected angular distributions of the mode ${B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$. The possibility of explaining such tensions within theories beyond the SM crucially depends on the size of the deviations of the Wilson coefficients of the effective Hamiltonian for this mode, in comparison to their SM values. We analyze this issue in the framework of the Randall--Sundrum model with custodial protection (${\mathrm{RS}}_{c}$); in our study we also consider the mode with $\ensuremath{\tau}$ leptons in the final state. We discuss the small deviations of ${\mathrm{RS}}_{c}$ results from SM ones, found scanning the parameter space of the model.
We study a set of exclusive $B$ and $B_s$ decay modes induced by the rare $b \to s ν\bar ν$ transition in the RS$_c$ model, an extra-dimensional extension of the standard model with warped 5D metric and extended gauge group. We emphasize the role of correlations among the observables, and their importance for detecting the predicted small deviations from the standard model expectations.
We study a set of exclusive $B$ and $B_s$ decay modes induced by the rare $b \to s \nu \bar \nu$ transition in the RS$_c$ model, an extra-dimensional extension of the standard model with warped 5D metric and extended gauge group. We emphasize the role of correlations among the observables, and their importance for detecting the predicted small deviations from the standard model expectations.
Both BABAR and LHCb Collaborations have recently claimed signals of possible deviations with respect to the Standard Model through the analyses of specific semileptonic B–meson decays. We firstly investigate the semileptonic b → c decay with a τ lepton in the final state for which new BABAR measurements are available, showing a deviation from the Standard Model at 3.4 σ level. We study the effects of a new tensor operator in the effective weak Hamiltonian on a set of observables, in semileptonic B → D(∗) modes as well as in semileptonic B and Bs decays to excited charmed mesons. Moreover, we discuss the phenomenology of the mode B → K∗ ℓ+ ℓ−, in the framework of a warped extra-dimensional model. Since a complete set of form factor almost independent observables have been recently measured by the LHCb Collaboration, with few sizable deviations with respect to the Standard Model in some of them, it would be interesting to put constraints on such a scenario from the FCNC transition b → sℓ+ℓ−.
We study a set of exclusive B and Bs decay modes induced by the rare b → sν ¯ ν transition in the RSc model, an extra-dimensional extension of the standard model with warped 5D metric and extended gauge group. We discuss the role of correlations among the observables, and their impor- tance for detecting the predicted small deviations from the standard model expectations.
The exclusive radiative B → K*γ, B → K*2γ, Bs → ϕγ and Λb → Λγ decays are studied in a new physics scenario with two universal extra dimensions compactified on a chiral square. The computed branching fractions depend on the size R of the extra dimensions; a comparison with the available measurements allows us to put bounds on such a fundamental parameter. The strongest bound GeV is obtained from the mode B0 → K*0γ using a set of form factors.
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