Search for Scalar Diphoton Resonances in the Mass Range 65–600 GeV with the ATLAS Detector inppCollision Data ats=8  TeV

Abstract

A search for scalar particles decaying via narrow resonances into two photons in the mass range 65-600 GeV is performed using 20.3 fb(-1) of √s 8 TeV pp collision data collected with the ATLAS detector at the Large Hadron Collider. The recently discovered Higgs boson is treated as a background. No significant evidence for an additional signal is observed. The results are presented as limits at the 95% confidence level on the production cross section of a scalar boson times branching ratio into two photons, in a fiducial volume where the reconstruction efficiency is approximately independent of the event topology. The upper limits set extend over a considerably wider mass range than previous searches.

Searching for Axionlike Particles with Ultraperipheral Heavy-Ion Collisions

“…We derive LHC limits using a diphoton search at m a > 60 GeV [39], and using the ATLAS 3γ search at lower masses [40]. For the latter search, we were not able to reliably extract a limit for m a 60 GeV with the available public information (see e.g.…”

“…For m a > 60 GeV, we calculate the fiducial cross section of pp → a → γγ and compare with the constraints in Ref. [39]. Associated production of aγ is also constrained by multi-photon searches at the LHC.…”

“…Shown for comparison is the limit from 36 pb −1 of exclusive p-p collisions [25] (red dot-dash). New and updated exclusion limits from LEPII (OPAL 2γ, 3γ) [38] and from the LHC (ATLAS 2γ, 3γ) [39,40] are indicated by the various shaded regions (see text). Right: The analogous results for the operator…”

Promising interpretation of diphoton resonance at 750 GeV

“…It is interesting to note that the CMS Collaboration did search for diphoton resonance [3] at √ s = 8 TeV and observed a slight excess ∼ 2σ at an invariant mass of about 750 GeV but on the other hand the ATLAS Collaboration did not go beyond the mass of 600 GeV for this channel [4].…”

A Heavy Scalar at the LHC from Vector-Boson Fusion

“…Early constraints [8][9][10] on the model parameters were obtained according to measurements on SM Higgs couplings, decay width, and direct detection at the LHC. Updated analyses based on the 8 TeV LHC data [11][12][13][14][15][16][17] can be found in [18][19][20][21][22][23].…”