@article{3037994,
    title = "Search for pair-produced neutralinos in events with photons and missing energy from e+e- collisions at √s=130-183 GeV",
    author = "Abreu, P. and Adye, T. and Adzic, P. and Ajinenko, I. and Alekseev, G.D. and Alemany, R. and Allport, P.P. and Almehed, S. and Amaldi, U. and Amato, S. and Anassontzis, E.G. and Andersson, P. and Andreazza, A. and Andringa, S. and Antilogus, P. and Apel, W.-D. and Arnoud, Y. and Åsman, B. and Augustin, J.-E. and Augustinus, A. and Baillon, P. and Bambade, P. and Barao, F. and Barbiellini, G. and Barbier, R. and Bardin, D.Y. and Barker, G. and Baroncelli, A. and Battaglia, M. and Baubillier, M. and Becks, K.-H. and Begalli, M. and Beilliere, P. and Belokopytov, Yu. and Benvenuti, A.C. and Berat, C. and Berggren, M. and Bertini, D. and Bertrand, D. and Besancon, M. and Bianchi, F. and Bigi, M. and Bilenky, M.S. and Bizouard, M.-A. and Bloch, D. and Blom, H.M. and Bonesini, M. and Bonivento, W. and Boonekamp, M. and Booth, P.S.L. and Borgland, A.W. and Borisov, G. and Bosio, C. and Botner, O. and Boudinov, E. and Bouquet, B. and Bourdarios, C. and Bowcock, T.J.V. and Boyko, I. and Bozovic, I. and Bozzo, M. and Branchini, P. and Brenke, T. and Brenner, R.A. and Bruckman, P. and Brunet, J.-M. and Bugge, L. and Buran, T. and Burgsmueller, T. and Buschmann, P. and Cabrera, S. and Caccia, M. and Calvi, M. and Camacho Rozas, A.J. and Camporesi, T. and Canale, V. and Carena, F. and Carroll, L. and Caso, C. and Castillo Gimenez, M.V. and Cattai, A. and Cavallo, F.R. and Cerruti, C. and Chabaud, V. and Charpentier, Ph. and Chaussard, L. and Checchia, P. and Chelkov, G.A. and Chierici, R. and Chliapnikov, P. and Chochula, P. and Chorowicz, V. and Chudoba, J. and Collins, P. and Colomer, M. and Contri, R. and Cortina, E. and Cosme, G. and Cossutti, F. and Cowell, J.-H. and Crawley, H.B. and Crennell, D. and Crosetti, G. and Cuevas Maestro, J. and Czellar, S. and Damgaard, G. and Davenport, M. and da Silva, W. and Deghorain, A. and Delia Ricca, G. and Delpierre, P. and Demaria, N. and de Angelis, A. and de Boer, W. and de Brabandere, S. and de Clercq, C. and de Lotto, B. and de Min, A. and de Paula, L. and Dijkstra, H. and di Ciaccio, L. and di Diodato, A. and Dolbeau, J. and Doroba, K. and Dracos, M. and Drees, J. and Dris, M. and Duperrin, A. and Durand, J.-D. and Ehret, R. and Eigen, G. and Ekelof, T. and Ekspong, G. and Ellert, M. and Elsing, M. and Engel, J.-P. and Erzen, B. and Espirito Santo, M. and Falk, E. and Fanourakis, G. and Fassouliotis, D. and Fayot, J. and Feindt, M. and Ferrari, P. and Ferrer, A. and Ferrer-Ribas, E. and Fichet, S. and Firestone, A. and Fischer, P.-A. and Flagmeyer, U. and Foeth, H. and Fokitis, E. and Fontanelli, F. and Franek, B. and Frodesen, A.G. and Fruhwirth, R. and Fulda-Quenzer, F. and Fuster, J. and Galloni, A. and Gamba, D. and Gamblin, S. and Gandelman, M. and Garcia, C. and Garcia, J. and Gaspar, C. and Gaspar, M. and Gasparini, U. and Gavillet, Ph. and Gazis, E.N. and Gele, D. and Gerber, J.-P. and Gerdyukov, L. and Ghodbane, N. and Gil, I. and Gìege, F. and Gokieli, R. and Golob, B. and Goncalves, P. and Gonzalez Caballero, I. and Gopal, G. and Gorn, L. and Gorski, M. and Gouz, Yu. and Gracco, V. and Grahl, J. and Graziani, E. and Green, C. and Gris, P. and Grzelak, K. and Gunther, M. and Guy, J. and Hahn, F. and Hahn, S. and Haider, S. and Hallgren, A. and Hamacher, K. and Harris, F.J. and Hedberg, V. and Heising, S. and Hernandez, J.J. and Herquet, P. and Herr, H. and Hessing, T.L. and Heuser, J.-M. and Higon, E. and Holmgren, S.-O. and Holt, P.J. and Holthuizen, D. and Hoorelbeke, S. and Houlden, M. and Hrubec, J. and Huet, K. and Hultqvist, K. and Jackson, J.N. and Jacobsson, R. and Jalocha, P. and Janik, R. and Jarlskog, C. and Jarlskog, G. and Jarry, P. and Jean-Marie, B. and Johansson, E.K. and Jonsson, P. and Joram, C. and Juillot, P. and Kapusta, F. and Karafasoulis, K. and Katsanevas, S. and Katsoufis, E.C. and Keranen, R. and Khomenko, B.A. and Khovanski, N.N. and Kiiskinen, A. and King, B. and Kjaer, N.J. and Klapp, O. and Klein, H. and Kluit, P. and Knoblauch, D. and Kokkinias, P. and Koratzinos, M. and Kostioukhine, V. and Kourkoumelis, C. and Kouznetsov, O. and Krammer, M. and Kreuter, C. and Kriznic, E. and Krstic, J. and Krumstein, Z. and Kubinec, P. and Kucewicz, W. and Kurvinen, K. and Lamsa, J.W. and Lane, D.W. and Langefeld, P. and Lapin, V. and Laugier, J.-P. and Lauhakangas, R. and Leder, G. and Ledroit, F. and Lefebure, V. and Leinonen, L. and Leisos, A. and Leitner, R. and Lemonne, J. and Lenzen, G. and Lepeltier, V. and Lesiak, T. and Lethuillier, M. and Libby, J. and Liko, D. and Lipniacka, A. and Lippi, I. and Loerstad, B. and Loken, J.G. and Lopes, J.H. and Lopez, J.M. and Lopez-Fernandez, R. and Loukas, D. and Lutz, P. and Lyons, L. and MacNaughton, J. and Mahon, J.R. and Maio, A. and Malek, A. and Malmgren, T.G.M. and Malychev, V. and Mandl, F. and Marco, J. and Marco, R. and Marechal, B. and Margoni, M. and Marin, J.-C. and Mariotti, C. and Markou, A. and Martinez-Rivero, C. and Martinez-Vidal, F. and Marti i Garcia, S. and Mastroyiannopoulos, N. and Matorras, F. and Matteuzzi, C. and Matthiae, G. and Mazik, J. and Mazzucato, F. and Mazzucato, M. and McCubbin, M. and McKay, R. and McNulty, R. and McPherson, G. and Meroni, C. and Meyer, W.T. and Miagkov, A. and Migliore, E. and Mirabito, L. and Mitaroff, W.A. and Mjoernmark, U. and Moa, T. and Moeller, R. and Moenig, K. and Monge, M.R. and Moreau, X. and Morettini, P. and Morton, G. and Mueller, U. and Muenich, K. and Mulders, M. and Mulet-Marquis, C. and Muresan, R. and Murray, W.J. and Muryn, B. and Myatt, G. and Myklebust, T. and Naraghi, F. and Navarria, F.L. and Navas, S. and Nawrocki, K. and Negri, P. and Neufeld, N. and Neumeister, N. and Nicolaidou, R. and Nielsen, B.S. and Nikolaenko, V. and Nikolenko, M. and Nomokonov, V. and Normand, A. and Nygren, A. and Obraztsov, V. and Olshevski, A.G. and Onofre, A. and Orava, R. and Orazi, G. and Osterberg, K. and Ouraou, A. and Paganoni, M. and Paiano, S. and Pain, R. and Paiva, R. and Palacios, J. and Palka, H. and Papadopoulou, T.D. and Papageorgiou, K. and Pape, L. and Parkes, C. and Parodi, F. and Parzefall, U. and Passeri, A. and Passon, O. and Pegoraro, M. and Peralta, L. and Pernicka, M. and Perrotta, A. and Petridou, C. and Petrolini, A. and Phillips, H.T. and Piana, G. and Pierre, F. and Pimenta, M. and Piotto, E. and Podobnik, T. and Pol, M.E. and Polok, G. and Poropat, P. and Pozdniakov, V. and Privitera, P. and Pukhaeva, N. and Pullia, A. and Radojicic, D. and Ragazzi, S. and Rahmani, H. and Rakoczy, D. and Ratoff, P.N. and Read, A.L. and Rebecchi, P. and Redaelli, N.G. and Regler, M. and Reid, D. and Reinhardt, R. and Renton, P.B. and Resvanis, L.K. and Richard, F. and Ridky, J. and Rinaudo, G. and Rohne, O. and Romero, A. and Ronchese, P. and Rosenberg, E.I. and Rosinsky, P. and Roudeau, P. and Rovelli, T. and Ruhlmann-Kleider, V. and Ruiz, A. and Saarikko, H. and Sacquin, Y. and Sadovsky, A. and Sajot, G. and Salt, J. and Sampsonidis, D. and Sannino, M. and Schneider, H. and Schwemling, Ph. and Schwickerath, U. and Schyns, M.A.E. and Scuri, F. and Seager, P. and Sedykh, Y. and Segar, A.M. and Sekulin, R. and Shellard, R.C. and Sheridan, A. and Siebel, M. and Silvestre, R. and Simard, L. and Simonetto, F. and Sisakian, A.N. and Skaali, T.B. and Smadja, G. and Smirnova, O. and Smith, G.R. and Sokolov, A. and Sopczak, A. and Sosnowski, R. and Spassov, T. and Spiriti, E. and Sponholz, P. and Squarcia, S. and Stampfer, D. and Stanescu, C. and Stanic, S. and Stapnes, S. and Stevenson, K. and Stocchi, A. and Strauss, J. and Strub, R. and Stugu, B. and Szczekowski, M. and Szeptycka, M. and Tabarelli, T. and Tchikilev, O. and Tegenfeldt, F. and Terranova, F. and Thomas, J. and Tilquin, A. and Timmermans, J. and Tkatchev, L.G. and Todorov, T. and Todorova, S. and Toet, D.Z. and Tomaradze, A. and Tome, B. and Tonazzo, A. and Tortora, L. and Transtromer, G. and Treille, D. and Tristram, G. and Troncon, C. and Tsirou, A. and Turluer, M.-L. and Tyapkin, I.A. and Tzamarias, S. and Ueberschaer, B. and Ullaland, O. and Uvarov, V. and Valenti, G. and Vallazza, E. and van Apeldoorn, G.W. and van Dam, P. and van Doninck, W.K. and van Eldik, J. and van Lysebetten, A. and van Vulpen, I. and Vassilopoulos, N. and Vegni, G. and Ventura, L. and Venus, W. and Verbeure, F. and Verlato, M. and Vertogradov, L.S. and Verzi, V. and Vilanova, D. and Vitale, L. and Vlasov, E. and Vodopyanov, A.S. and Voulgaris, G. and Vrba, V. and Wahlen, H. and Walck, C. and Weiser, C. and Wicke, D. and Wickens, J.H. and Wilkinson, G.R. and Winter, M. and Witek, M. and Wolf, G. and Yi, J. and Yushchenko, O. and Zalewska, A. and Zalewski, P. and Zavrtanik, D. and Zevgolatakos, E. and Zimin, N.I. and Zucchelli, G.C. and Zumerle, G.",
    journal = "The European Physical Journal C - Particles and Fields",
    year = "1999",
    volume = "6",
    number = "3",
    pages = "371-384",
    publisher = "Springer New York LLC",
    issn = "1434-6044, 1434-6052",
    doi = "10.1007/s100529801044",
    abstract = "The events with two photons and missing (transverse) energy collected by the DELPHI detector at centre-of-mass energies between 130 GeV and 183 GeV have been studied to search for processes of the type e+e- → YY with the subsequent decay Y → Xγ, where X is an undetectable neutral particle. Reactions of this kind are expected in supersymmetric models, where the Y particle can be either the lightest neutralino, decaying to a photon and a gravitino, or the next-to-lightest neutralino, decaying to a photon and the lightest neutralino. To study the case of long-lived Y particles, a search for single-photon events with the reconstructed photon axis pointing far from the beam interaction region has also been performed. No evidence for a deviation from Standard Model expectations has been observed in the data and upper limits have been derived on the signal cross-section as a function of the the X and Y masses and of the Y mean decay path."
}