Multi-Photon Events with Large Missing Energy in $e^{+}e^{-}$ Collisions at $\sqrt{s}=192-209 GeV$

Events with a final state consisting of two or more photons and large missing transverse energy have been observed in e+e- collisions at centre-of-mass energies in the range 192 - 209 GeV using the OPAL detector at LEP. Cross-section measurements are performed within the kinematic acceptance of the...

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Detalles Bibliográficos
Autores principales: Abbiendi, G., Ainsley, C., Akesson, P.F., Alexander, G., Allison, John, Amaral, P., Anagnostou, G., Anderson, K.J., Asai, S., Axen, D., Azuelos, G., Bailey, I., Barberio, E., Barillari, T., Barlow, R.J., Batley, R.J., Bechtle, P., Behnke, T., Bell, Kenneth Watson, Bell, P.J., Bella, G., Bellerive, A., Benelli, G., Bethke, S., Biebel, O., Boeriu, O., Bock, P., Boutemeur, M., Braibant, S., Brigliadori, L., Brown, Robert M., Buesser, K., Burckhart, H.J., Campana, S., Carnegie, R.K., Carter, A.A., Carter, J.R., Chang, C.Y., Charlton, D.G., Ciocca, C., Csilling, A., Cuffiani, M., Dado, S., De Roeck, A., De Wolf, E.A., Desch, K., Dienes, B., Donkers, M., Dubbert, J., Duchovni, E., Duckeck, G., Duerdoth, I.P., Etzion, E., Fabbri, F., Feld, L., Ferrari, P., Fiedler, F., Fleck, I., Ford, M., Frey, A., Gagnon, P., Gary, John William, Gaycken, G., Geich-Gimbel, C., Giacomelli, G., Giacomelli, P., Giunta, Marina, Goldberg, J., Gross, E., Grunhaus, J., Gruwe, M., Gunther, P.O., Gupta, A., Hajdu, C., Hamann, M., Hanson, G.G., Harel, A., Hauschild, M., Hawkes, C.M., Hawkings, R., Hemingway, R.J., Herten, G., Heuer, R.D., Hill, J.C., Hoffman, Kara Dion, Horvath, D., Igo-Kemenes, P., Ishii, K., Jeremie, H., Jovanovic, P., Junk, T.R., Kanaya, N., Kanzaki, J., Karlen, D., Kawagoe, K., Kawamoto, T., Keeler, R.K., Kellogg, R.G., Kennedy, B.W., Kluth, S., Kobayashi, T., Kobel, M., Komamiya, S., Kramer, T., Krieger, P., von Krogh, J., Kruger, K., Kuhl, T., Kupper, M., Lafferty, G.D., Landsman, H., Lanske, D., Layter, J.G., Lellouch, D., Lettso, J., Levinson, L., Lillich, J., Lloyd, S.L., Loebinger, F.K., Lu, J., Ludwig, A., Ludwig, J., Mader, W., Marcellini, S., Martin, A.J., Masetti, G., Mashimo, T., Mattig, Peter, McKenna, J., McPherson, R.A., Meijers, F., Menges, W., Merritt, F.S., Mes, H., Meyer, Niels T., Michelini, A., Mihara, S., Mikenberg, G., Miller, D.J., Moed, S., Mohr, W., Mori, T., Mutter, A., Nagai, K., Nakamura, I., Nanjo, H., Neal, H.A., Nisius, R., O'Neale, S.W., Oh, A., Oreglia, M.J., Orito, S., Pahl, C., Pasztor, G., Pater, J.R., Pilcher, J.E., Pinfold, J., Plane, David E., Poli, B., Pooth, O., Przybycien, M., Quadt, A., Rabbertz, K., Rembser, C., Renkel, P., Roney, J.M., Rozen, Y., Runge, K., Sachs, K., Saeki, T., Sarkisyan, E.K.G., Schaile, A.D., Schaile, O., Scharff-Hansen, P., Schieck, J., Schorner-Sadenius, T., Schroder, Matthias, Schumacher, M., Scott, W.G., Seuster, R., Shears, T.G., Shen, B.C., Sherwood, P., Skuja, A., Smith, A.M., Sobie, R., Soldner-Rembold, S., Spano, F., Stahl, A., Strom, David M., Strohmer, R., Tarem, S., Tasevsky, M., Teuscher, R., Thomson, M.A., Torrence, E., Toya, D., Tran, P., Trigger, I., Trocsanyi, Z., Tsur, E., Turner-Watson, M.F., Ueda, I., Ujvari, B., Vollmer, C.F., Vannerem, P., Vertesi, R., Verzocchi, M., Voss, H., Vossebeld, J., Ward, C.P., Ward, D.R., Watkins, P.M., Watson, A.T., Watson, N.K., Wells, P.S., Wengler, T., Wermes, N., Wilson, G.W., Wilson, J.A., Wolf, G., Wyatt, T.R., Yamashita, S., Zer-Zion, D., Zivkovic, Lidija
Lenguaje:eng
Publicado: 2004
Materias:
Particle Physics - Experiment
Acceso en línea:https://dx.doi.org/10.1016/j.physletb.2004.09.059
http://cds.cern.ch/record/786367
Descripción
Sumario:Events with a final state consisting of two or more photons and large missing transverse energy have been observed in e+e- collisions at centre-of-mass energies in the range 192 - 209 GeV using the OPAL detector at LEP. Cross-section measurements are performed within the kinematic acceptance of the selection and compared with the expectation from the Standard Model process e+e- -> nu nu gamma gamma(gamma). No evidence for new physics contributions to this final state is observed. Upper limits on sigma (e+e- -> XX) BR^2(X -> Ygamma) are derived for the case of stable and invisible Y. In the case of massive Y the combined limits obtained from all the data range from 10 fb to 60 fb, while for the special case of massless Y the range is 20 fb to 40 fb. The limits apply to pair production of excited neutrions (X=nu^*,Y=nu), to neutralino production (X=~chi^0_2, Y=~chi^0_1) and to supersymmetric models in which X=~chi^0_1 and Y=~G is a light gravitino.

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