No abstract
We analyze the angular distributions ofB →K * (→Kπ) + − andB →K + − decays in the region of low hadronic recoil in a model-independent way by taking into account the complete set of dimension-six operators [sΓb][¯ Γ ]. We obtain several novel low-recoil observables with high sensitivity to non-standard-model Dirac structures, including CP-asymmetries which do not require flavor tagging. The transversity observables H (1,3,4,5) T are found to be insensitive to hadronic matrix elements and their uncertainties even when considering the complete set of operators. In the most general scenario we show that the low recoil operator product expansion can be probed at the fewpercent level using the angular observable J7. Higher sensitivities are possible assuming no tensor contributions, specifically by testing the low-recoil relation |H(1) T | = 1. We explicitly demonstrate the gain in reach of the low-recoil observables in accessing the ratio |C 9 /C 10 | compared to the forwardbackward asymmetry, and probing CP-violating right-handed currents Im C 10 . We give updated Standard Model predictions for key observables inB →K ( * ) + − decays.
We provide results for the full set of form factors describing semileptonic Bmeson transitions to pseudoscalar mesons π, K,D and vector mesons ρ, K * ,D * . Our results are obtained within the framework of QCD Light-Cone Sum Rules with B-meson distribution amplitudes. We recalculate and confirm the results for the leading-twist twoparticle contributions in the literature. Furthermore, we calculate and provide new expressions for the two-particle contributions up to twist four. Following new developments for the three-particle distribution amplitudes, we calculate and provide new results for the complete set of three-particle contributions up to twist four. The form factors are computed numerically at several phase space points using up-to-date input parameters, including correlations across phase space points and form factors. We use a model ansatz for all contributing B-meson distribution amplitudes that is self-consistent up to twistfour accuracy. We find that the higher-twist two-particle contributions have a substantial impact on the results, and dominate over the three-particle contributions. Our numerical results, including correlations, are provided as machine-readable ancillary files. We discuss the qualitative phenomenological impact of our results on the present b anomalies.
When revisiting our fits in order to expand the above work, errors in the implementation of analytical expressions of the observables have been encountered. One of these errors affects the branching ratio of B → K + − at low q 2 in the presence of chirality-flipped operators. Carefully checking our results, we also found that systematic uncertainties of the lattice results of the B → K ( * ) form factors had been incorrectly neglected.After correcting these errors, we replace Tables 2 ("Postdiction" rows only), 3, 6, 4, and 5, as well as Figs. 2, 3, and 4. We also replace selected parts of Sect. 4 that are not given in the tables.While our main conclusions stay as they are, some details are adjusted. Our revised conclusions are given at the end of this erratum. Result Statistical approachFor the "selection" data set, we erroneously included the observables P i at high q 2 . Hence there are now N = 20 experimental inputs, two theory constraints, and dim ν = 24. (4.7)Our corrected result for the deviation in the (C 7 -C 9 ) from the SM expectation is 2.5σ , and solution A is favored over solution B with R A :R B = 82 %:18 %. Solution A is described by the 1D marginalized 68 % credibility regions For the data set "selection", the credibility regions in Fig. 2 are larger now as the observables P i at high q 2 are no longer part of it. Fit in the extended SM+SM basisWe now find that, of all four solutions, A and D dominate over B and C in terms of the posterior mass: R A :R B :R C :R D = 37 %:14 %:15 %:34 %. 123
No abstract
We study the differential decay rate for the rare Λ b → Λ(→ N π) + − transition, including a determination of the complete angular distribution, assuming unpolarized Λ b baryons. On the basis of a properly chosen parametrization of the various helicity amplitudes, we provide expressions for the angular observables within the Standard Model and a subset of new physics models with chirality-flipped operators. Hadronic effects at low recoil are estimated by combining information from lattice QCD with (improved) formfactor relations in Heavy Quark Effective Theory. Our estimates for large hadronic recoil -at this stage -are still rather uncertain because the baryonic input functions are not so well known, and non-factorizable spectator effects have not been worked out systematically so far. Still, our phenomenological analysis of decay asymmetries and angular observables for Λ b → Λ(→ N π) + − reveals that this decay mode can provide new and complementary constraints on the Wilson coefficients in radiative and semileptonic b → s transitions compared to the corresponding mesonic modes.
We study the decayB →K + − for = e, µ, τ with a softly recoiling kaon, that is, for high dilepton invariant masses q 2 of the order of the b-quark mass. This kinematic region can be treated within an operator product expansion and simplified using heavy quark symmetry, leading to systematic predictions for heavy-to-light processes such asB →K ( * ) + − . We show that the decay rates of bothB →K * + − andB →K + − decays into light leptons depend on a common combination of short-distance coefficients. The corresponding CP-asymmetries are hence identical. Furthermore we present low recoil predictions forB →K + − observables, including the flat term in the angular distribution which becomes sizable for taus. We work out model-independently the constraints on ∆B = 1 operators using the most recent data from the experiments BaBar, Belle, CDF and LHCb. For constructive interference with the standard model, generic new physics is pushed up to scales above 44 TeV at 95% CL. Assuming none or small CP-violation we obtain a lower bound on the position of the zero of the forward-backward asymmetry ofB 0 →K * 0 + − decays as q 2 0 > 1.7 GeV 2 , which improves to q 2 0 > 2.6 GeV 2 for a standard model-like sign b → sγ amplitude.
We revisit the theoretical predictions and the parametrization of non-local matrix elements in rare $$ {\overline{B}}_{(s)}\to \left\{{\overline{K}}^{\left(\ast \right)},\phi \right\}{\mathrm{\ell}}^{+}{\mathrm{\ell}}^{-} $$ B ¯ s → K ¯ ∗ ϕ ℓ + ℓ − and $$ {\overline{B}}_{(s)}\to \left\{{\overline{K}}^{\ast },\phi \right\}\gamma $$ B ¯ s → K ¯ ∗ ϕ γ decays. We improve upon the current state of these matrix elements in two ways. First, we recalculate the hadronic matrix elements needed at subleading power in the light-cone OPE using B-meson light-cone sum rules. Our analytical results supersede those in the literature. We discuss the origin of our improvements and provide numerical results for the processes under consideration. Second, we derive the first dispersive bound on the non-local matrix elements. It provides a parametric handle on the truncation error in extrapolations of the matrix elements to large timelike momentum transfer using the z expansion. We illustrate the power of the dispersive bound at the hand of a simple phenomenological application. As a side result of our work, we also provide numerical results for the Bs → ϕ form factors from B-meson light-cone sum rules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.