Challenges in the detection of long lived particles with ATLAS: the Hidden valley scenario

A number of extensions of the Standard Model result in particles that are neutral, weakly-coupled and have macroscopic decay lengths that can be comparable with LHC detector dimensions[1, 2, 3]. These long lived particles occur in many models; in the Hidden Valley (HV) Scenario a new sector is weakly coupled to the Standard Model and results in neutral long lived HV particles ($pi_{v}$) that decay to heavy quark pairs and tau pairs. These particles can be produced in Higgs boson decays, SUSY processes or $Z^prime$ decays. \ We present the results of a first study of the ATLAS Detector performance for the Higgs decay $h^0 ightarrowpi_vpi_v$, where the $pi_v$ is neutral and has a displaced decay mainly to bottom quarks. The initial goal of our study is to obtain benchmark triggers for processes with such non-standard signatures in the ATLAS apparatus.