$b\to cl\nu$ anomalies in light of vector and scalar interactions

TL;DR

This paper investigates the potential of scalar and vector interactions to explain $b o cl u$ anomalies, showing that scalar interactions alone, if complex, can account for the anomalies despite existing bounds.

Contribution

It provides a model-independent analysis demonstrating that scalar interactions, especially complex ones, can explain the anomalies, challenging previous assumptions.

Findings

Scalar interactions alone can explain anomalies if they are complex.

Extended scalar sector models cannot fully account for anomalies at 3σ.

Both scalar and vector interactions can potentially explain the anomalies.

Abstract

We perform a model independent analysis of the charged current $b\to cl\nu$ anomalies under the presence of scalar and vector interactions. The analysis is carried out in two stages: (a) under the presence of both (left-handed) vector and scalar interactions and (b) under the presence of scalar interactions alone. We find that even after stringent bounds from similar quark-level processes such as $B_c\to\tau\nu$, such scenarios have the potential to explain the aforementioned anomalies. Contrary to the general notion, we show that even scalar interactions alone can explain such anomalies, provided they are complex. However, extended scalar sector models are unable to comply with these anomalies to $\sim 3\sigma$. We further illustrate our results with the help of three benchmark models corresponding to the presence of (i) both scalar and vector (ii) real scalar and (iii) complex scalar interactions.