Search for Hidden Valley decays with the ATLAS experiment

Many extensions of the Standard Model (SM) include neutral weakly-coupled particles that can be long-lived and to which the Higgs may decay. These long-lived particles occur in many models, including gauge-mediated extensions of the Minimal Supersymmetric Standard Model (MSSM), MSSM with R-parity violation, inelastic dark matter and the Hidden Valley (HV) scenario. Results are presented on the first ATLAS search for possible rare Higgs boson decays to pair of neutral, long-lived hidden-sector particles that lead to final states containing fermion−anti-fermion pairs or pairs of collimated lepton jets. No excess of events above the expected background have been observed for 1.94 fb-1 of data collected in 2011. Limits are presented as a function of the proper lifetime of the long-lived neutral particle.