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This work discusses the ongoing research on the search for radions and Higgs particles at the Large Hadron Collider (LHC). It focuses on quantum excitations of brane distance in RS theories, potential changes in the ggH cross section, and the detectability of radions and Higgs particles through various decay modes. The text explores the difficulties and possibilities of observing certain processes at the LHC and the perspectives for identifying scalar particles in different mass ranges. It also highlights the importance of precise measurements and the exploration of complementarity between the LHC and future colliders.
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Radion-Higgs Search at LHC/LC Work in progress RADIONS Albert De Roeck (CERN)
Trouble in Higgs Paradise @LHC ? (e.g. Rizzo, Hewett, Dominici,Gunion Giudice, Wells, Rattazzi…etc) Radions! • Quantum excitations of brane distance in RS theories Horror! ggH cross section disappears!! Can change things a lot for the LHC RADIONS Albert De Roeck (CERN)
Radions RADIONS Albert De Roeck (CERN)
Radions RADIONS Albert De Roeck (CERN)
RADIONS Albert De Roeck (CERN)
Exercise… • Check where the Higgs discovery at LHC gets more difficult/impossible • Can one observe gg ZZ* in those regions • perspectives for identifying the nature of the observed scalar at a LHC & LC Tool used HDECAY, introducing relevant terms for radions (J. Gunion/D. Dominici) Radion ZZ* 4l 50 GeV < M < 400 GeV Take experimental bounds (Tevatron/LEP) into account Higgs H ZZ* 4l H ttH ttbb low Higgs mass range 120-140 GeV RADIONS Albert De Roeck (CERN)
Higgs/Radion detectability Other decays need to be looked into (H) LHC will essentially always see a scalar with 30 fb-1 RADIONS Albert De Roeck (CERN)
Higgs/Radion Detectability MH=130 GeV MH=140 GeV MH=115 GeV Becomes better for heavier Higgs Decay to study HH for high mass LC should always see the light Higgs & in almost entire region RADIONS Albert De Roeck (CERN)
Couplings at a LC RADIONS Albert De Roeck (CERN)
Ratio of couplings Effects are ~1-5%: Difficult to establish at LHC However: absolute cross section & ggH/WW HH possible handles RADIONS Albert De Roeck (CERN)
LC measurements Measure precisely Higgs to bb and WW(*) couplings Contours of 2.5 evidence for radion mixing effects RADIONS Albert De Roeck (CERN)
ZZ branching ratio RADIONS Albert De Roeck (CERN)
Plans • Explore further decay modes • LHC with 100-300 fb-1 • Total cross sections • Explore LC/LHC complementarity fully • Determination of Radion parameters RADIONS Albert De Roeck (CERN)