Search for exotic Higgs boson decays to merged photons employing a novel deep learning technique at CMS

A search for exotic Higgs boson decays, of the form H --> aa, with a --> yy is performed. The hypothetical a is a light, odd parity pseudoscalar decaying to two highly merged photons, reconstructed as a single photon object in the CMS detector operating at the CERN LHC. A novel, end-to-end deep learning-based technique is used to directly measure the invariant mass of merged a --> yy candidates, additionally providing a first measurement of the invariant mass spectrum of objects reconstructed as single photons.