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 E-T and azimuthal angle separation Delta phi ~ 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.

T., A., M., A., B., Á.G., S., A., D., A., A., A., et al. (2012). Observation of Exclusive gamma gamma Production in p(p)over-bar Collisions at root s=1.96 TeV. PHYSICAL REVIEW LETTERS, 108(8) [10.1103/PhysRevLett.108.081801].

Observation of Exclusive gamma gamma Production in p(p)over-bar Collisions at root s=1.96 TeV

BARRIA, PATRIZIA;GAROSI, PAOLA;MAESTRO, PAOLO;RUFFINI, FABRIZIO;SCRIBANO, ANGELO;SQUILLACIOTI, PAOLA;
2012

Abstract

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 E-T and azimuthal angle separation Delta phi ~ 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.
T., A., M., A., B., Á.G., S., A., D., A., A., A., et al. (2012). Observation of Exclusive gamma gamma Production in p(p)over-bar Collisions at root s=1.96 TeV. PHYSICAL REVIEW LETTERS, 108(8) [10.1103/PhysRevLett.108.081801].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/21388
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