Search for a scalar top almost degenerate with the lightest neutralino in e +e − collisions at [formula omitted] up to 202 GeV

• Published in: Physics letters. B 2000-09, Vol.488 (3), p.234-246
• Main Authors: Decamp, D., Lees, J.-P., Martin, F., Merle, E., Fernandez-Bosman, M., Paneque, D., Ruiz, H., Colaleo, A., Creanza, D., De Filippis, N., Nuzzo, S., Raso, G., Selvaggi, G., Tempesta, P., Tricomi, A., Zito, G., Xue, S., Dissertori, G., Forty, R.W., Greening, T.C., Janot, P., Jost, B., Rolandi, L., Schlatter, D., Schmitt, M., Tejessy, W., Teubert, F., Ajaltouni, Z., Dessagne, S., Guicheney, C., Henrard, P., Jousset, J., Pallin, D., Hansen, J.D., Nilsson, B.S., Wäänänen, A., Kyriakis, A., Simopoulou, E., Vayaki, A., Blondel, A., Brient, J.-C., Machefert, F., Zachariadou, K., Mannocchi, G., Chalmers, M., Kennedy, J., O'Shea, V., Smith, D., Tittel, K., Beuselinck, R., Marinelli, N., Thompson, J.C., Buck, P.G., Clarke, D.P., Foster, F., Kleinknecht, K., Müller, A.-S., Nürnberger, H.-A., Renk, B., Schmeling, S., Wachsmuth, H., Zeitnitz, C., Ziegler, T., Curtil, C., Payre, P., Tilquin, A., Aleppo, M., Dietl, H., Ganis, G., Heister, A., Settles, R., Wiedenmann, W., Boucrot, J., Grivaz, J.-F., Heusse, Ph, Serin, L., Giassi, A., Sciabà, A., Blair, G.A., Green, M.G., Colas, P., Faı̈f, G., Lançon, E., Locci, E., Rander, J., Seager, P., Loomis, C., Kim, H.Y., Konstantinidis, N., McNeil, M.A., Combley, F., Hodgson, P.N., Affholderbach, K., Misiejuk, A., Cranmer, K., Elmer, P., Kile, J., McNamara III, P.A., Pan, Y.B., Saadi, Y.
• Format: Article
• Language: English
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/S0370-2693(00)00893-5

Data collected at centre-of-mass energies from 189 GeV to 202 GeV by the ALEPH detector at LEP corresponding to an integrated luminosity of 411 pb −1, are analysed in a search for the scalar top in the decay channels t ̃ → c/uχ for small mass differences between the stop and the lightest neutralino. No evidence for deviations from the Standard Model expectation is found and a lower limit of 59 GeV/ c 2 is set for the stop mass, independent of the stop to neutralino mass difference and of the stop lifetime.