Observation of exclusive gamma gamma production in ppˉ collisions at √s=1.96 TeV

0388734 - FZÚ 2013 RIV US eng J - Journal Article
Aaltonen, T. - Albrow, M.G. - Gonzalez, B.A. - Lysák, Roman … Total 475 authors
Observation of exclusive gamma gamma production in ppˉ collisions at √s=1.96 TeV.
Physical Review Letters. Roč. 108, č. 8 (2012), "081801-1"-"081801-7". ISSN 0031-9007. E-ISSN 1079-7114
R&D Projects: GA MŠMT LC527
Institutional research plan: CEZ:AV0Z10100502
Keywords : electromagnetic showers * exchange two-photon * quantum electrodynamics * photon transverse energy * anti-p p exclusive reaction * rapidity * CDF
Subject RIV: BF - Elementary Particles and High Energy Physics
Impact factor: 7.943, year: 2012
http://link.aps.org/doi/10.1103/PhysRevLett.108.081801

We have observed exclusive gamma gamma production in proton-antiproton collisions at root s = 1.96 TeV, using data from 1.11 +/- 0.07 fb(-1) integrated luminosity taken by the Run II Collider Detector at Fermilab. We selected events with two electromagnetic showers, each with transverse energy E-T > 2.5 GeV and pseudorapidity |eta| < 1.0, with no other particles detected in -7.4 < eta < +7.4. The two showers have similar ET and azimuthal angle separation Delta phi similar to pi; 34 events have two charged particle tracks, consistent with the QED process p<(p)over bar> --> p + e(+)e(-) + (p) over bar by two-photon exchange, while 43 events have no charged tracks. The number of these events that are exclusive pi(0)pi(0) is consistent with zero and is < 15 at 95% C. L. The cross section for p<(p)over bar> --> p + gamma gamma + (p) over bar with |eta(gamma)| < 1.0 and E-T(gamma) > 2.5 GeV is 2.48(-0.35)(+0.40)(stat)(-0.51)(+0.40)(syst) pb.
Permanent Link: http://hdl.handle.net/11104/0217639