Search for Resonances in Diphoton Events at $\sqrt{s}
Search for Resonances in Diphoton Events at $\sqrt{s}

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Published: 2016

Total Pages: 50

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Searches for new resonances decaying into two photons in the ATLAS experiment at the CERN Large Hadron Collider are described. The analysis is based on proton-proton collision data corresponding to an integrated luminosity of 3.2 fb-1 at √s = 13 TeV recorded in 2015. Two searches are performed, one targeted at a spin-2 particle of mass larger than 500 GeV, using Randall-Sundrum graviton states as a benchmark model, and one optimized for a spin-0 particle of mass larger than 200 GeV. Varying both the mass and the decay width, the most significant deviation from the background-only hypothesis is observed at a diphoton invariant mass around 750 GeV with local significances of 3.8 and 3.9 standard deviations in the searches optimized for a spin-2 and spin-0 particle, respectively. The global significances are estimated to be 2.1 standard deviations for both analyses. As a result, the consistency between the data collected at 13 TeV and 8 TeV is also evaluated. Limits on the production cross section times branching ratio to two photons for the two resonance types are reported.

Search for Diphoton Resonances in the Mass Range from 150 to 850 GeV in Pp Collisions at $\sqrt{s}$
Search for Diphoton Resonances in the Mass Range from 150 to 850 GeV in Pp Collisions at $\sqrt{s}$

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Published: 2015

Total Pages: 38

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Results are presented of a search for heavy particles decaying into two photons. The analysis is based on a 19.7fb-1 sample of proton-proton collisions at $\sqrt{s}$ = 8 TeV collected with the CMS detector at the CERN LHC. The diphoton mass spectrum from 150 to 850 GeV is used to search for an excess of events over the background. The search is extended to new resonances with natural widths of up to 10% of the mass value. No evidence for new particle production is observed and limits at 95% confidence level on the production cross section times branching fraction to diphotons are determined. These limits are interpreted in terms of two-Higgs-doublet model parameters.

A Search for New Physics in Photon-lepton Events in Proton-antiproton Collisions At[radical] S
A Search for New Physics in Photon-lepton Events in Proton-antiproton Collisions At[radical] S

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Published: 2003

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We present the results of a search in p[bar p] collisions at[radical]s= 1.8 TeV for anomalous production of events containing a photon with large transverse energy and a lepton (e or[mu]) with large transverse energy, using 86 pb[sup -1] of data collected at the Collider Detector at Fermilab during the 1994-95 collider run at the Fermilab Tevatron. The presence of large missing transverse energy (E[sub T]), additional photons, or additional leptons in these events is also analyzed. The results are consistent with standard model expectations, with the possible exception of photon-lepton events with large E[sub T], for which the probability of a statistical fluctuation of the standard model expectation up to and above the observed level is 0.7%.

Search for Diphoton Events with Large Missing Transverse Energy in 6.3 Fb$^{-1}$ of $\mathbf{p\bar{p}}$ Collisions at $\mathbf{\sqrt{s}
Search for Diphoton Events with Large Missing Transverse Energy in 6.3 Fb$^{-1}$ of $\mathbf{p\bar{p}}$ Collisions at $\mathbf{\sqrt{s}

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Published: 2010

Total Pages: 7

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We report a search for diphoton events with large missing transverse energy produced in p{bar p} collisions at √s = 1.96 TeV. The data were collected with the D0 detector at the Fermilab Tevatron Collider, and correspond to 6.3 fb−1 of integrated luminosity. The observed missing transverse energy distribution is well described by the standard model prediction, and 95% C.L. limits are derived on two realizations of theories beyond the standard model. In a gauge mediated supersymmetry breaking scenario, the breaking scale [Lambda] is excluded for [Lambda]