Test of the $R(D^{(*)})$ anomaly at the LHC

TL;DR

This paper investigates the potential signals of new physics explaining the $R(D^{(*)})$ anomaly at the LHC, showing current searches already constrain most favored parameter regions, especially via $ au u$ resonance channels.

Contribution

It provides a direct search analysis for new charged particles at the LHC to test explanations of the $R(D^{(*)})$ anomaly, updating bounds on these models.

Findings

LHC $ au u$ resonance searches cover most favored parameter space.

Current bounds surpass those from $B_c$ decay constraints.

Charged scalar mass bounds depend on the specific model parameters.

Abstract

There are discrepancies between the experimental results and the Standard Model predictions, in the lepton flavor universality of the semileptonic $B$ decays: $B \to D^{(*)} \ell \nu$. As the new physics interpretations, new charged vector and charged scalar fields, that dominantly couple to the second and third generations, have been widely discussed. In this paper, we study the signals of the new particles at the LHC, and test the interpretations via the direct search for the new resonances. In particular, we see that the $\tau \nu$ resonance search at the LHC has already covered most of the parameter regions favored by the Belle and BaBar experiments. We find that the bound is already stronger than the one from the $B_c$ decay depending on the mass of charged scalar.