Searches for Soft Unclustered Energy Patterns with the CMS experiment and studies of radiation damage in plastic scintillators

by Christos Papageorgakis

Thursday Dec 18, 2025, 12:30 PM → 1:30 PM America/Los_Angeles

48/2-224 - Madrone (SLAC)

The data collected by the Compact Muon Solenoid experiment at the Large Hadron Collider allows for tests of the Standard Model of Particle Physics and searches for physics beyond the Standard Model. In this talk, I will present searches for a beyond-the-standard-model phenomenon, the Soft Unclustered Energy Pattern (SUEP), and studies of radiation damage to plastic scintillators, used to produce signals in the CMS calorimeter system. 

 

The effects of ionizing radiation on the light output and optical properties of plastic scintillators are assessed across a range of scintillator materials, dopants, sample thicknesses, doses, and dose rates. Depending on the dose rate, the samples exhibit internal regions with different refractive indices separated by a visible boundary. Measurements of the boundary depth indicate compatibility with the expected oxygen penetration depth during irradiation. The refractive indices of the internal regions are higher than those of the outer regions, and they match those of unirradiated samples. The results highlight the importance of oxygen presence on radiation damage during irradiation.

 

Dark sectors with a large t'Hooft coupling can give rise to SUEPs, which are final states characterized by large charged particle multiplicities. Searches for SUEPs with CMS data will be presented. Emphasis will be given to a new search strategy involving muons. The expected 95% CL upper limits for the cross sections indicate that, once unblinded, the search will be able to set upper limits about 3-4 orders of magnitude below the theory predictions.

https://stanford.zoom.us/j/98973156241?pwd=cEU5RFdlVXoyc0JTeTlDMkozKzQ5UT09

talk_SLAC_20251218.pdf