HEP Seminar: Monday, October 26, 2020 - ATLAS Search for Non-Pointing and Delayed Photons

Event Date: 

Monday, October 26, 2020 - 12:00pm

Event Location: 

  • Zoom
  • HEP Seminar

ATLAS Search for Non-Pointing and Delayed Photons

Devin Mahon, Columbia Univeristy

Years of dedicated searches for supersymmetry (SUSY) and other well-motivated extensions of the Standard Model have so far all come up empty-handed. But what if we’re looking in the wrong places? Most beyond the Standard Model (BSM) searches tend to focus on prompt signals, but just as there are long-lived particles in the Standard Model, BSM physics may too feature such particles. In this talk, I introduce a novel search for displaced photons with the ATLAS detector. We target our search on the relatively unconstrained branching ratio of the Higgs boson to invisible particles, where there is still ample room for BSM phenomena. Exploiting the longitudinal segmentation and the excellent precision timing of the ATLAS detector’s liquid argon electromagnetic calorimeter, we are able to extract the striking, smoking-gun signature of a displaced photon that both fails to point back to the interaction point and arrives significantly delayed. I discuss in detail the optimization of the event selection and binning strategy in the context of our completely data-driven background estimation method to achieve maximum significance in the context of a chosen SUSY signal model while maintaining model-independent sensitivity to any soft displaced photons. To provide in-depth context to the measurement of our analysis variables, I also present my work on the calorimeter itself including the development of the front-end readout electronics, the offline timing calibration, and Run 2 operations.

 

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