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Search for new Physics with Long-Lived Particles Decaying to Photons and Missing Energy in pp Collisions at a Center-of-Mass Energy of 7 TeV with the CMS Experiment at the LHC

  • Author(s): Liu, Hongliang
  • Advisor(s): Hanson, Gail
  • et al.
Abstract

We perform a search for long-lived neutral particles decaying into a photon and invisible particles in pp collisions at a center-of-mass energy of 7 TeV at the Large Hadron Collider. In the context of gauge mediated supersymmetry with the lightest neutralino as the next-to-lightest supersymmetric particle and the gravitino as the lightest supersymmetric particle, the neutralino can decay into a gravitino and a photon with a non-zero lifetime. The impact parameter of the photon relative to the beam-beam collision point can be reconstructed using converted photons. The method is sensitive to lifetimes of the order of $\mathcal{O}$(0.1 ns). The data sample corresponds to an integrated luminosity of $2.1 \pm 0.1~\rm{fb^{-1}}$ recorded in the first part of 2011 by the CMS experiment at the LHC at $\sqrt{s}$ = 7 TeV. The search is performed using events containing photons, missing transverse energy and jets. Upper limits at the $\rm{95\%}$ confidence level are presented on the cross section for such particles from pair-production, each of which decays into a photon and invisible particles.

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