Abstract
We investigate the possibility of indirectly constraining the B^{+}rightarrow K^{+}tau ^+tau ^- decay rate using precise data on the B^{+}rightarrow K^{+}mu ^+mu ^- dimuon spectrum. To this end, we estimate the distortion of the spectrum induced by the B^{+}rightarrow K^{+}tau ^+tau ^-rightarrow K^{+} mu ^+mu ^- re-scattering process, and propose a method to simultaneously constrain this (non-standard) contribution and the long-distance effects associated to hadronic intermediate states. The latter are constrained using the analytic properties of the amplitude combined with data and perturbative calculations. Finally, we estimate the sensitivity expected at the LHCb experiment with present and future datasets. We find that constraints on the branching fraction of O(10^{-3}), competitive with current direct bounds, can be achieved with the current dataset, while bounds of O(10^{-4}) could be obtained with the LHCb upgrade-II luminosity.
Highlights
In recent years, discrepancies between the observed values and the Standard Model (SM) predictions of the leptonflavour universality (LFU) ratios RD(∗) [1,2,3,4,5] and RK (∗) [6,7,8,9], characterizing the semileptonic transitions b → clν and b → sll, have sparked great interest
In this work we investigate the possibility of indirectly constraining the b → sτ +τ − amplitude via its imprint on the B+ → K +μ+μ− dimuon spectrum
If the branching ratio B(B+ → K +τ +τ −) were significantly enhanced over its SM value, it would induce a peculiar distortion of the B+ → K +μ+μ− spectrum, characterised by a cusp at q2
Summary
Discrepancies between the observed values and the Standard Model (SM) predictions of the leptonflavour universality (LFU) ratios RD(∗) [1,2,3,4,5] and RK (∗) [6,7,8,9], characterizing the semileptonic transitions b → clν and b → sll, have sparked great interest. This approach is not suitable for our purpose, which requires a reliable description of the whole spectrum, and in particular of the resonance region To achieve this goal, we adopt a datadriven approach which takes full advantage of the known analytic properties of the amplitude: knowing the precise location of all one- and two-particle hadronic thresholds, we use subtracted dispersion relations to describe the q2-dependence of the whole spectrum in terms of a series of (q2-independent) hadronic parameters, which are fitted from data. We adopt a datadriven approach which takes full advantage of the known analytic properties of the amplitude: knowing the precise location of all one- and two-particle hadronic thresholds, we use subtracted dispersion relations to describe the q2-dependence of the whole spectrum in terms of a series of (q2-independent) hadronic parameters, which are fitted from data This method can be considered a generalisation of the approaches proposed in Ref.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: The European physical journal. C, Particles and fields
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
