Searching for New Long Lived Particles in Heavy Ion Collisions at the LHC

TL;DR

Heavy ion collisions at the LHC offer a promising new environment for detecting long-lived particles, leveraging looser triggers and unique production mechanisms to enhance search sensitivity compared to proton collisions.

Contribution

This paper demonstrates the potential of heavy ion collisions at the LHC for long-lived particle searches, highlighting advantages like looser triggers and new production channels.

Findings

Looser triggers in heavy ion collisions increase observable events.

Heavy ion collisions can be competitive with proton collisions for certain long-lived particles.

Lighter ion collisions are also promising for New Physics searches.

Abstract

We show that heavy ion collisions at the LHC provide a promising environment to search for new long lived particles in well-motivated New Physics scenarios. One advantage lies in the possibility to operate the main detectors with looser triggers, which can increase the number of observable events by orders of magnitude if the long lived particles are produced with low transverse momentum. In addition, the absence of pileup in heavy ion collisions can avoid systematic nuisances that will be present in future proton runs, such as the problem of vertex mis-identification. Finally, there are new production mechanisms that are absent or inefficient in proton collisions. We show that the looser triggers alone can make searches in heavy ion data competitive with proton data for the specific example of heavy neutrinos in the Neutrino Minimal Standard Model, produced in the decay of B mesons. Our results suggest that collisions of ions lighter than lead, which are currently under discussion in the heavy ion community, are well-motivated from the viewpoint of searches for New Physics.