Abstract
Theory uncertainties on non-local hadronic effects limit the New Physics discovery potential of the rare decays B → K∗μ+μ−. We investigate prospects to disentangle New Physics effects in the short-distance coefficients from these effects. Our approach makes use of an event-by-event amplitude analysis, and relies on a particular parametrisation of the non-local contributions. We find that non-standard effects in the short-distance coefficients can be successfully disentangled from non-local hadronic effects. The impact of the truncation on the parametrisation of non-local contributions to the Wilson coefficients are for the first time systematically examined and prospects for their precise determination are discussed. Theoretical inputs on the non-local matrix elements beyond the physically- accessible phase space are crucial to stabilise the determination of Wilson coefficients, while we find that physical observables are unaffected by these uncertainties. Compared to other methods, our approach provides for a more precise extraction of the angular observables from data.
Highlights
The Wilson coefficients Ci for the basis of dimension-six operators Oi are fitted from data
Theoretical inputs on the non-local matrix elements beyond the physicallyaccessible phase space are crucial to stabilise the determination of Wilson coefficients, while we find that physical observables are unaffected by these uncertainties
Given this recent progress on the non-local matrix elements we aim to study the possibility of applying the z expansion to future experimental analyses: first, we want to establish to which extent information concerning the non-local matrix elements can be inferred from experimental data of the semileptonic decay
Summary
Assuming on-shell K∗ dominance, the decay B → K∗(→ Kπ)μ+μ− involves four kinematic variables: the dimuon mass square q2, as well as two helicity angles within the μ+μ− and Kπ decay planes, respectively, and the azimuthal angle between the planes (see [21, 22] and subsequent publications). In our nominal fits up to z2, we float the full set of 39 nuisance parameters {αj}, with Gaussian constraints as described above. Exception to this are marked appropriately in the text. The exact numbers of simulated events for each experiment are listed in table 1 Modelling of both the detector resolution or detection efficiency is hardly possible without access to (non-public) information of the current B physics experiments Belle (II) and LHCb. We assume perfect resolution and efficiency in our studies herefrom out — unless otherwise stated. While the restriction to a sub-set of operators could introduce some model dependency, we are convinced that it suffices to demonstrate the separability of hadronic and NP contributions to C9 as we set out to do in this article
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