Abstract
Searches for new phenomena in high-mass diphoton final states with the ATLAS experiment at the LHC are presented. The analysis is based on pp collision data corresponding to an integrated luminosity of 36.7 fb−1 at a centre-of-mass energy s=13 TeV recorded in 2015 and 2016. Searches are performed for resonances with spin 0, as predicted by theories with an extended Higgs sector, and for resonances with spin 2, using a warped extra-dimension model as a benchmark model, as well as for non-resonant signals, assuming a large extra-dimension scenario. No significant deviation from the Standard Model is observed. Upper limits are placed on the production cross section times branching ratio to two photons as a function of the resonance mass. In addition, lower limits are set on the ultraviolet cutoff scale in the large extra-dimensions model.
Highlights
New high-mass states decaying into two photons are predicted in extensions of the Standard Model (SM)
This Letter presents an update of the searches for new high-mass states decaying into two photons, using both 2015 and 2016 proton–prot√on collision datasets recorded at a centre-of-mass energy s = 13 TeV by the ATLAS detector at the CERN Large Hadron Collider (LHC), corresponding to a total integrated luminosity of 36.7 fb−1
From the many extensions of the SM that predict new high-mass resonances decaying into two photons, the two benchmark signal models studied in Ref. [1] are considered: a spin-0 resonance ( X ) as predicted in theories with an extended Higgs sector [2,3,4,5,6,7,8], and the lightest Kaluza–Klein (KK) [9] spin-2 graviton excitation (G∗) of a Randall–Sundrum [10] model with one warped extra dimension, later referred to as RS1
Summary
New high-mass states decaying into two photons are predicted in extensions of the Standard Model (SM). This Letter presents an update of the searches for new high-mass states decaying into two photons, using both 2015 and 2016 proton–prot√on (pp) collision datasets recorded at a centre-of-mass energy s = 13 TeV by the ATLAS detector at the CERN Large Hadron Collider (LHC), corresponding to a total integrated luminosity of 36.7 fb−1. From the many extensions of the SM that predict new high-mass resonances decaying into two photons, the two benchmark signal models studied in Ref. The ATLAS Collaboration / Physics Letters B 775 (2017) 105–125 signal in the diphoton decay channel were carried out by the ATLAS [17] and CMS [18] experiments based on LHC Run 1 data. The substantial increase in the centre-of-mass energy in LHC Run 2 greatly enhances the sensitivity to the ADD scenario at higher mass scales [19]
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