The Study of Rare $B_c\rightarrow D^{(*)}_{s,d}l\bar{l}$ Decays

TL;DR

This paper investigates rare Bc meson decays into D* and D mesons with leptons within the Standard Model, highlighting the significance of various decay diagrams and proposing new methods to reduce resonance effects.

Contribution

It provides a comprehensive analysis of decay contributions, emphasizing the importance of annihilation and cascade diagrams, and introduces new strategies to mitigate resonance pollution.

Findings

Annihilation and cascade diagrams significantly affect decay observables.

Color-favored cascade decays enhance resonance contributions.

New cut regions help reduce resonance pollution.

Abstract

In this paper, we study rare decays $B_c\rightarrow D^{(*)}_{s,d}l\bar{l}$ within the Standard Model. The penguin, box, annihilation, color-favored cascade and color-suppressed cascade contributions are included. Based on our calculation, the annihilation and color-favored cascade diagrams play important roles in the differential branching fractions, forward-backward asymmetries, longitudinal polarizations of the final vector mesons and leptonic longitudinal polarization asymmetries. More importantly, color-favored cascade decays largely enhance the resonance cascade contributions. To avoid the resonance cascade contribution pollution, new cutting regions are put forward.