Observation of Light-by-Light Scattering in Ultraperipheral Pb + Pb Collisions with the ATLAS Detector
This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √s<sub>NN</sub> = 5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb⁻¹, collected in November 2018 by the ATLAS experime...
| Authors: | , , , , , , , , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2019 |
| Country: | Argentina |
| Institution: | Universidad Nacional de La Plata |
| Repository: | SEDICI (UNLP) |
| Language: | English |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/147258 |
| Online Access: | http://sedici.unlp.edu.ar/handle/10915/147258 |
| Access Level: | Open access |
| Keyword: | Ciencias Exactas Física relativistic heavy-ion collisions light-by-light scattering |
| Summary: | This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at √s<sub>NN</sub> = 5.02 TeV. The analysis is conducted using a data sample corresponding to an integrated luminosity of 1.73 nb⁻¹, collected in November 2018 by the ATLAS experiment at the LHC. Light-by-light scattering candidates are selected in events with two photons produced exclusively, each with transverse energy Eᵞ<sub>T</sub> > 3 GeV and pseudorapidity |ηᵧ|<2.4, diphoton invariant mass above 6 GeV, and small diphoton transverse momentum and acoplanarity. After applying all selection criteria, 59 candidate events are observed for a background expectation of 12±3 events. The observed excess of events over the expected background has a significance of 8.2 standard deviations. The measured fiducial cross section is 78±13(stat)±7(syst)±3(lumi) nb. |
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