Abstract
Many models of dark matter predict long-lived particles (LLPs) that can give rise to striking signatures at the LHC. Existing searches for displaced vertices are however tailored towards heavy LLPs. In this work we show that this bias severely affects their sensitivity to LLPs with masses at the GeV scale. To illustrate this point we consider two dark sector models with light LLPs that decay hadronically: a strongly-interacting dark sector with long-lived exotic mesons, and a Higgsed dark sector with a long-lived dark Higgs boson. We study the sensitivity of an existing ATLAS search for displaced vertices and missing energy in these two models and find that current track and vertex cuts result in very low efficiency for light LLPs. To close this gap in the current search programme we suggest two possible modifications of the vertex reconstruction and the analysis cuts. We calculate projected exclusion limits for these modifications and show that they greatly enhance the sensitivity to LLPs with low mass or short decay lengths.
Highlights
JHEP04(2021)210 second example is a Higgsed dark sector, in which the masses of the various particles are generated via spontaneous symmetry breaking [21, 22]
We study the sensitivity of an existing ATLAS search for displaced vertices and missing energy in these two models and find that current track and vertex cuts result in very low efficiency for light long-lived particles (LLPs)
Long-lived particles with masses at the GeV scale are a generic prediction of many dark sector models
Summary
We introduce two different models of dark sectors containing stable DM candidates as well as unstable states at the GeV scale: a strongly interacting dark sector and a Higgsed dark sector Both of these models predict LHC events with a combination of invisible and long-lived particles in the final state, leading to the characteristic signature of missing energy together with a displaced vertex, which will be the focus of our analysis below. The quark coupling gq, on the other hand, determines the production cross section for dark sector states, and their decay width back into SM particles, which is decisive for the collider phenomenology. We will treat gq as a free parameter in the following
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
