Prospects for $B_c^+$ and $B^+\to \tau^+ \nu_\tau$ at FCC-ee

Author:

Marco Fedele, Clément Helsens, Donal Hill, Syuhei Iguro, Markus Klute, Xunwu Zuo

Keyword:

High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph)

journal:

TTP23-015, P3H-23-28

date:

2023-05-03 16:00:00

Abstract

The prospects are presented for precise measurements of the branching ratios of the purely leptonic $B_c^+ \to \tau^+ \nu_\tau$ and $B^+ \to \tau^+ \nu_\tau$ decays at the Future Circular Collider (FCC). Common FCC software tools are employed in all steps of this study. This work is focused on the hadronic $\tau^{+} \to \pi^+ \pi^+ \pi^- \bar{\nu}_\tau$ decay in both $B_c^+ \to \tau^+ \nu_\tau$ and $B^+ \to \tau^+ \nu_\tau$ processes. Events are selected with two Boosted Decision Tree algorithms to optimise the separation between the two signal processes as well as the generic hadronic $Z$ decay backgrounds. The range of the expected precision for both signals are evaluated in different scenarios of non-ideal background modelling. The theoretical impacts of such measurements are discussed in both the Standard Model context, for measurements of CKM matrix elements, as well as New Physics cases, for interpretations in the generic Two-Higgs-doublet model and leptoquark models.

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