# Long Live the Higgs Factory: Higgs Decays to Long-Lived Particles at Future Lepton Colliders

## TL;DR

This paper explores the potential of future lepton colliders to detect exotic Higgs decays into long-lived particles with displaced hadronic signatures, using realistic tracking strategies to improve sensitivity.

## Contribution

It introduces a realistic search strategy for LLPs at future lepton colliders and compares its sensitivity with the LHC, including interpretations in various theoretical models.

## Key findings

- Projected sensitivity is competitive with the LHC.
- Potential for superior sensitivity at lower LLP masses.
- Complementarity between LLP searches and Higgs coupling measurements.

## Abstract

We initiate the study of exotic Higgs decays to long-lived particles (LLPs) at proposed future lepton colliders, focusing on scenarios with displaced hadronic final states. Our analysis entails a realistic tracker-based search strategy involving the reconstruction of displaced secondary vertices and the imposition of selection cuts appropriate for eliminating the largest irreducible backgrounds. The projected sensitivity is broadly competitive with that of the LHC and potentially superior at lower LLP masses. In addition to forecasting branching ratio limits, which may be freely interpreted in a variety of model frameworks, we interpret our results in the parameter space of a Higgs portal Hidden Valley and various incarnations of neutral naturalness, illustrating the complementarity between direct searches for LLPs and precision Higgs coupling measurements at future lepton colliders.