# Interference effects in MSSM Higgs searches at the LHC

## TL;DR

This paper investigates how interference effects between nearly degenerate Higgs states in the MSSM affect LHC search results, revealing that ignoring these effects can lead to incorrect exclusion limits.

## Contribution

It provides the first detailed analysis of interference effects in MSSM Higgs searches at the LHC, highlighting their significant impact on experimental constraints.

## Key findings

- Interference effects can significantly alter Higgs search sensitivities.
- Parameter regions previously considered excluded are unconstrained when interference is included.
- Destructive interference can mask the presence of heavy Higgs bosons in LHC data.

## Abstract

Complex parameters in the MSSM lead to mixing and interference between the two heavier neutral CP-even and CP-odd Higgs states. These effects can become very large in the case of almost degenerate states. In a CP-violating benchmark scenario, we investigate phenomenological implications of such interferences in view of the LHC searches for heavy Higgs bosons decaying to a pair of $\tau$-leptons and produced in gluon fusion and in association with b-quarks. Strongly destructive effects leave parameter regions unconstrained that would be regarded as excluded if no interference terms were taken into account.