Search for light gravitinos in events with photons and missing transverse momentum at HERA

H1 Collaboration, The and Henderson, Robert C. W. and Sloan, Terry (2005) Search for light gravitinos in events with photons and missing transverse momentum at HERA. Physics Letters B, 616 (1-2). pp. 31-42. ISSN 0370-2693

Abstract

A search for gravitinos produced in e±p collisions is performed using the H1 detector at HERA. The data were taken at a centre-of-mass energy of 319 GeV and correspond to an integrated luminosity of 64.3 pb−1 for e+p collisions and 13.5 pb−1 for e−p collisions. If R-parity is not conserved, the t-channel exchange of a selectron can produce a neutralino, which, in models where the gravitino is the lightest supersymmetric particle, subsequently decays into a photon and a light gravitino. The resulting event signature, which involves an isolated photon, a jet and missing transverse energy, is analysed for the first time at HERA. No deviation from the Standard Model is found. Exclusion limits on the cross section and on R-parity-violating Yukawa couplings are derived in a Gauge Mediated Supersymmetry Breaking scenario. The results are independent of the squark sector. Neutralinos and supersymmetric partners of the left-handed electron with masses up to 112 GeV and 164 GeV, respectively, can be ruled out at the 95% confidence level for R-parity-violating couplings λ′ equal to 1, in some parts of the parameter space of the considered model.