Search for stop production in R-parity-violating supersymmetry at HERA

A search for stop production in R-parity-violating supersymmetry has been performed in ep interactions with the ZEUS detector at HERA, using an integrated luminosity of 65 pb. At HERA, the R-parity-violating coupling λ allows resonant squark production, ed → q̃. Since the lowest-mass squark state in most supersymmetry models is the light stop, t̃, this search concentrated on production of t̃, followed either by a direct R-parity-violating decay, or by the gauge decay to bχ̃+1 . No evidence for stop production was found and limits were set on λ131 as a function of the stop mass in the framework of the Minimal Supersymmetric Standard Model. The results have also been interpreted in terms of constraints on the parameters of the minimal Supergravity model. The ZEUS Collaboration S. Chekanov, M. Derrick, S. Magill, S. Miglioranzi, B. Musgrave, D. Nicholass, J. Repond, R. Yoshida Argonne National Laboratory, Argonne, Illinois 60439-4815, USA n M.C.K. Mattingly Andrews University, Berrien Springs, Michigan 49104-0380, USA N. Pavel , A.G. Yagües Molina Institut für Physik der Humboldt-Universität zu Berlin, Berlin, Germany S. Antonelli, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, M. Bindi, D. Boscherini, A. Bruni, G. Bruni, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, G. Iacobucci, A. Margotti, R. Nania, A. Polini, L. Rinaldi, G. Sartorelli, A. Zichichi University and INFN Bologna, Bologna, Italy e G. Aghuzumtsyan, D. Bartsch, I. Brock, S. Goers, H. Hartmann, E. Hilger, H.-P. Jakob, M. Jüngst, O.M. Kind, E. Paul, J. Rautenberg, R. Renner, U. Samson, V. Schönberg, M. Wang, M. Wlasenko Physikalisches Institut der Universität Bonn, Bonn, Germany b N.H. Brook, G.P. Heath, J.D. Morris, T. Namsoo H.H. Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom m M. Capua, S. Fazio, A. Mastroberardino, M. Schioppa, G. Susinno, E. Tassi Calabria University, Physics Department and INFN, Cosenza, Italy e J.Y. Kim, K.J. Ma Chonnam National University, Kwangju, South Korea g Z.A. Ibrahim, B. Kamaluddin, W.A.T. Wan Abdullah Jabatan Fizik, Universiti Malaya, 50603 Kuala Lumpur, Malaysia r Y. Ning, Z. Ren, F. Sciulli Nevis Laboratories, Columbia University, Irvington on Hudson, New York 10027 o J. Chwastowski, A. Eskreys, J. Figiel, A. Galas, M. Gil, K. Olkiewicz, P. Stopa, L. Zawiejski The Henryk Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland i L. Adamczyk, T. Bo ld, I. Grabowska-Bo ld, D. Kisielewska, J. Lukasik, M. Przybycień, L. Suszycki Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Cracow, Poland p