Hecate

Abstract

The next generation of circular high energy collider is expected to be a lepton collider, FCC-ee at CERN or CEPC in China. However, the civil engineering concepts foresee to equip these colliders with bigger detector caverns than one would need for a lepton collider, so that they can be used for a hadron collider that may be installed in the same tunnel without further civil engineering. This opens up the possibility to install extra instrumentation at the cavern walls to search for new long-lived particles at the lepton collider. We use the example of heavy neutral leptons to show that such an installation could improve the sensitivity to the squared mixing parameter by almost half an order of magnitude.

The Present and Future Status of Heavy Neutral Leptons

“…This is the motivation behind e.g. HECATE [440], a long-lived particle detector concept for the FCC-ee or CEPC facility. The civil engineering of the FCC-ee will have much bigger detector caverns than needed for a lepton collider experiments since they are intended to be used later for a hadron collider facility, which requires larger volumes.…”

The present and future status of heavy neutral leptons

“…This is the motivation behind e.g. HECATE [510], a LLP detector concept for the FCC-ee or CEPC facility. The civil engineering of the FCC-ee will have much bigger detector caverns than needed for a lepton collider experiments since they are intended to be used later for a hadron collider facility, which requires larger volumes.…”

“…The curves from [506,723,726] have been re-scaled to an integrated luminosity consistent with [85,451,516]. The sensitivity of future colliders could be considerably improved with dedicated long-lived particle detectors [510,511,514,729]. Cartan theory [289].…”

Distinguishing Dirac and Majorana Heavy Neutrinos at Lepton Colliders

“…) The dependence of (4) on 𝑙 cyl and 𝑑 cyl quantifies the sensitivity gain with additional detectors [25]. The smallest mixing that can be probed is given by the maximum of 𝑈 2 min in (3) and and (4); one can estimate the point where they cross at 𝑀 ≃ 2.75 𝑌 𝐺 2 𝐹 c dec 𝑑 2/3 cyl 𝑙 1/3 cyl /p 𝑁 −1/6…”

“…Distinguishing Dirac and Majorana Heavy Neutrinos at Lepton Colliders Marco Drewes be achieved with additional detectors [25] can be estimated with ( 4). This shows the potential of lepton collider to test neutrino mass models and leptogenesis [13].…”