Photoproduction of J/psi and of high mass e+e- in ultra-peripheral Au+Au collisions at sqrt(s_NN) = 200 GeV

Photoproduction of J/psi and of high mass e+e- in ultra-peripheral Au+Au collisions at sqrt(s_NN) = 200 GeV

We present the first measurement of photoproduction of J/psi and of two-photon production of high-mass e+e- pairs in electromagnetic (or ultra-peripheral) nucleus-nucleus interactions, using Au+Au data at sqrt(s_NN) = 200 GeV. The events are tagged with forward neutrons emitted following Coulomb exc...

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Veröffentlicht in:Physics letters. B 2009-08, Vol.679, p.321-329
Hauptverfasser: Afanasiev, S., Aidala, C., Ajitanand, N.N., Akiba, Y., Alexander, J., Al-Jamel, A., Aoki, K., Aphecetche, Laurent, Armendariz, R., Aronson, S.H., Averbeck, R., Awes, T.C., Azmoun, B., Babintsev, V., Baldisseri, A., Barish, K.N., Barnes, P.D., Bassalleck, B., Bathe, S., Batsouli, S., Baublis, V., Bauer, F., Bazilevsky, A., Belikov, S., Bennett, R., Berdnikov, Y., Bjorndal, M.T., Boissevain, J.G., Borel, H., Boyle, K., Brooks, M.L., Brown, D.S., Bucher, D., Buesching, H., Bumazhnov, V., Bunce, G., Burward-Hoy, J.M., Butsyk, S., Campbell, S., Chai, J.-S., Chernichenko, S., Chiba, J., Chi, C.Y., Chiu, M., Choi, I.J., Chujo, T., Cianciolo, V., Cleven, C.R., Cobigo, Y., Cole, B.A., Comets, M.P., Conesa del Valle, Z., Constantin, P., Csanad, M., Csorgo, T., Dahms, T., Das, K., David, G., Delagrange, H., Denisov, A., d'Enterria, D., Deshpande, A., Desmond, E.J., Dietzsch, O., Dion, A., Drachenberg, J.L., Drapier, O., Drees, A., Dubey, A.K., Durum, A., Dzhordzhadze, V., Efremenko, Y.V., Egdemir, J., Enokizono, A., En'Yo, H., Espagnon, B., Esumi, S., Fields, D.E., Fleuret, F., Fokin, S.L., Forestier, B., Fraenkel, Z., J.E. Frantz, 2, Franz, A., Frawley, A.D., Fukao, Y., Fung, S.-Y., Gadrat, S., Gastineau, F., Germain, Marie, Glenn, A., Gonin, M., Gosset, J., Goto, Y., Granier de Cassagnac, R., Grau, N., Greene, S.V., Grosse Perdekamp, M., Gunji, T., Gustafsson, H.-A.
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Sprache:eng
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Nuclear Experiment
Physics
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Zusammenfassung:We present the first measurement of photoproduction of J/psi and of two-photon production of high-mass e+e- pairs in electromagnetic (or ultra-peripheral) nucleus-nucleus interactions, using Au+Au data at sqrt(s_NN) = 200 GeV. The events are tagged with forward neutrons emitted following Coulomb excitation of one or both Au^{star} nuclei. The event sample consists of 28 events with m_{e+e-} > 2 GeV/c^2 with zero like-sign background. The measured cross sections at midrapidity of d\sigma / dy (J/psi + Xn, y=0) = 76 +/- 33 (stat) +/- 11 (syst) micro b and d^2\sigma/dm dy (e^+e^- + Xn, y=0) = 86 +/- 23 (stat) +/- 16 (syst) micro b/(GeV/c^2) for m_{e+e-} \in [2.0,2.8] GeV/c^2 are consistent with various theoretical predictions.
ISSN:0370-2693
DOI:10.1016/j.physletb.2009.07.061