# Higgsino Dark Matter or Not: Role of Disappearing Track Searches at the LHC and Future Colliders

## TL;DR

This paper proposes a new disappearing-track search strategy at colliders to detect Higgsino dark matter, especially in scenarios where gauginos are very heavy, complementing non-accelerator experiments.

## Contribution

It introduces a novel collider search method using two-hit pixel detector techniques to identify long-lived charged Higgsinos in heavy gaugino scenarios.

## Key findings

- Future 33 TeV colliders can probe almost pure Higgsino dark matter.
- Disappearing-track searches with displaced-vertex reconstruction improve background suppression.
- Strategy enhances detection prospects for electroweak-charged dark matter candidates.

## Abstract

Higgsino in supersymmetric standard models is known to be a promising candidate for dark matter in the Universe. Its phenomenological property is strongly affected by the gaugino fraction in the Higgsino-like state. If this is sizable, in other words, if gaugino masses are less than ${\cal O}(10)$ TeV, we may probe the Higgsino dark matter in future non-accelerator experiments such as dark matter direct searches and measurements of electric dipole moments. On the other hand, if gauginos are much heavier, then it is hard to search for Higgsino in these experiments. In this case, due to a lack of gaugino components, the mass difference between the neutral and charged Higgsinos is uniquely determined by electroweak interactions to be around $350$ MeV, which makes the heavier charged state rather long-lived, with a decay length of about $1$ cm. In this letter, we argue that a charged particle with a flight length of ${\cal O}(1)$ cm can be probed in disappearing-track searches if we require only two hits in the pixel detector. Even in this case, we can reduce background events with the help of the displaced-vertex reconstruction technique. We study the prospects of this search strategy at the LHC and future colliders for the Higgsino dark matter scenario. It is found that an almost pure Higgsino is indeed within the reach of the future $33$ TeV collider experiments. We then discuss that the interplay among collider and non-accelerator experiments plays a crucial role in testing the Higgsino dark matter scenarios. Our strategy for disappearing-track searches can also enlarge the discovery potential of pure wino dark matter as well as other electroweak-charged dark matter candidates.