Abstract
Many extensions of the Standard Model (SM) include neutral weakly-coupled particles that can be long-lived. These long-lived particles occur in many models, included gauge-mediated extensions of the Minimal Supersymmetric Model (MSSM), MSSM with R-parity violation, inelastic dark matter and the Hidden Valley (HV) scenario. Results are presented on the first ATLAS searches at the LHC 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 has been observed for 1.9 fb−1 of data collected in 2011 at a center of mass energy of 7 TeV. Limits are presented as a function of the proper lifetime of the long-lived neutral particle.
Highlights
Many extensions of the Standard Model (SM) include neutral weakly-coupled particles that can be long-lived. These long-lived particles occur in many models, included gauge-mediated extensions of the Minimal Supersymmetric Model (MSSM), MSSM with R-parity violation, inelastic dark matter and the Hidden Valley (HV) scenario
Results are presented on the first ATLAS searches at the LHC 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
In 1.9 fb−1 of p-p collision data at a center-of-mass energy of 7 TeV there is no evidence of an excess of events containing two isolated, back-to-back vertices in the ATLAS muon spectrometer (MS)
Summary
Several models of physics beyond the SM predict the existence of Hidden Sectors able to comunicate to the SM through several portals (Higgs, Z’, loop of SUSY particles). A light Higgs boson can decay to particles of the hidden sector [1] such as the long-lived pseudo-scalar vpion (πv) or scalar hidden fermions. These HV particles can decay back in the standard sector to fermion antifermion pairs or collimated lepton-jets [2]. Lifetimes can be comparable to ATLAS [3] dimensions, leading to displaced decays far from the interaction point. Dedicated trigger algorithms [4] and reconstruction techniques have been developed
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