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Searching for dark radiation at the LHC

Bernreuther, Elias; Kahlhoefer, Felix 1; Lucente, Michele; Morandini, Alessandro
1 Institut für Theoretische Teilchenphysik (TTP), Karlsruher Institut für Technologie (KIT)

Abstract:

In this work we explore the intriguing connections between searches for long-lived particles (LLPs) at the LHC and early universe cosmology. We study the non-thermal production of ultra-relativistic particles (i.e. dark radiation) in the early universe via the decay of weak-scale LLPs and show that the cosmologically interesting range ∆Neff ~ 0.01–0.1 corresponds to LLP decay lengths in the mm to cm range. These decay lengths lie at the boundary between prompt and displaced signatures at the LHC and can be comprehensively explored by combining searches for both. To illustrate this point, we consider a scenario where the LLP decays into a charged lepton and a (nearly) massless invisible particle. By reinterpreting searches for promptly decaying sleptons and for displaced leptons at both ATLAS and CMS we can then directly compare LHC exclusions with cosmological observables. We find that the CMB-S4 target value of ∆Neff = 0.06 is already excluded by current LHC searches and even smaller values can be probed for LLP masses at the electroweak scale.


Verlagsausgabe §
DOI: 10.5445/IR/1000150131
Veröffentlicht am 23.08.2022
Originalveröffentlichung
DOI: 10.1007/JHEP08(2022)169
Scopus
Zitationen: 1
Web of Science
Zitationen: 4
Dimensions
Zitationen: 3
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Theoretische Teilchenphysik (TTP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2022
Sprache Englisch
Identifikator ISSN: 1029-8479
KITopen-ID: 1000150131
Erschienen in Journal of High Energy Physics
Verlag Scuola Internazionale Superiore di Studi Avanzati (SISSA)
Band 2022
Heft 8
Seiten 169
Bemerkung zur Veröffentlichung Gefördert durch SCOAP3
Vorab online veröffentlicht am 18.08.2022
Nachgewiesen in Dimensions
arXiv
Web of Science
Scopus
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