LPC Physics Forum

Thursday 27 Feb 2025, 13:00 → 15:00 US/Central

Sunrise (WH11NE) (FNAL/Zoom)

https://cern.zoom.us/j/96898909340

13:00 → 14:00 PREFACE: A possible new LLP search in the very forward region

PREFACE is proposed to search for Long-Lived Particles, LLPs, in the very forward direction of CMS starting in Run 4. It is based on the FACET proposal (Forward Aperture CMS ExTension) to look for neutral particles at small angles which penetrate > 30m of iron absorber and decay after 100m to SM particles. FACET requires a 1m diameter beam pipe which would not be possible before Run 5, and would have a very high background mainly from scattered protons to the side of the outgoing beam. PREFACE avoids these issues by being above the standard HL-LHC beam pipe, with added shielding between that pipe and the fiducial decay volume, nominally a 10m long rectangular box 0.8m x 0.8m. It has silicon tracking, HGCAL modules and a permanent magnet for muons. A fast trigger selects two or more (straight) tracks with a small distance of closest approach in air from an incoming neutral, with one or more muons or high energy electrons. Decays X -> tau+tau, c-cbar and b-bbar from a dark higgs should have no background and are competitive with other searches, having 10 – 1000 (depending on the lifetime) times more acceptance than FASER.

Speakers: Michael Albrow, Michael Albrow (Fermi National Accelerator Lab. (US)), Mike Albrow (Fermi National Accelerator Laboratory)