This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at sNN=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 ETγ>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.

Observation of Light-by-Light Scattering in Ultraperipheral Pb+Pb Collisions with the ATLAS Detector / Aad, G., Abbott, B., Abbott, D.C., Abdinov, O., Abed Abud, A., Abeling, K., Abhayasinghe, D.K., Abidi, S.H., Abouzeid, O.S., Abraham, N.L., Abramowicz, H., Abreu, H., Abulaiti, Y., Acharya, B.S., Achkar, B., Adachi, S., Adam, L., Adam Bourdarios, C., Adamczyk, L., Adamek, L., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 123:5(2019), p. 052001. [10.1103/PhysRevLett.123.052001]

Observation of Light-by-Light Scattering in Ultraperipheral Pb+Pb Collisions with the ATLAS Detector

Follega F. M.;Iuppa R.;Ricci E.;
2019-01-01

Abstract

This Letter describes the observation of the light-by-light scattering process, γγ→γγ, in Pb+Pb collisions at sNN=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 ETγ>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.
2019
5
Aad, G.; Abbott, B.; Abbott, D. C.; Abdinov, O.; Abed Abud, A.; Abeling, K.; Abhayasinghe, D. K.; Abidi, S. H.; Abouzeid, O. S.; Abraham, N. L.; Abram...espandi
Observation of Light-by-Light Scattering in Ultraperipheral Pb+Pb Collisions with the ATLAS Detector / Aad, G., Abbott, B., Abbott, D.C., Abdinov, O., Abed Abud, A., Abeling, K., Abhayasinghe, D.K., Abidi, S.H., Abouzeid, O.S., Abraham, N.L., Abramowicz, H., Abreu, H., Abulaiti, Y., Acharya, B.S., Achkar, B., Adachi, S., Adam, L., Adam Bourdarios, C., Adamczyk, L., Adamek, L., et al.. - In: PHYSICAL REVIEW LETTERS. - ISSN 0031-9007. - 123:5(2019), p. 052001. [10.1103/PhysRevLett.123.052001]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11572/318603
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