Prospects for B c + $$ {B}_c^{+} $$ → τ + ν τ at FCC-ee

Abstract

Abstract This paper presents the prospects for a precise measurement of the branching fraction of the leptonic B c + $$ {B}_c^{+} $$ → τ + ν τ decay at the Future Circular Collider (FCC-ee) running at the Z -pole. A detailed description of the simulation and analysis framework is provided. To select signal candidates, two Boosted Decision Tree algorithms are employed and optimised. The first stage suppresses inclusive b b ¯ $$ b\overline{b} $$ , c c ¯ $$ c\overline{c} $$ , and q q ¯ $$ q\overline{q} $$ backgrounds using event-based topological information. A second stage utilises the properties of the hadronic τ + → π + π + π − ν ¯ $$ \overline{\nu} $$ τ decay to further suppress these backgrounds, and is also found to achieve high rejection for the B + → τ + ν τ background. The number of B c + $$ {B}_c^{+} $$ → τ + ν τ candidates is estimated for various Tera-Z scenarios, and the potential precision of signal yield and branching fraction measurements evaluated. The phenomenological impact of such measurements on various New Physics scenarios is also explored.

Keywords

• B physics
• e +-e − Experiments
• Flavor physics
• Tau Physics