Search for the Decay D⁰ → γγ and Measurement of the decay D⁰ → π⁰π⁰

The Standard Model is the best current description of fundamental interactions and particles; however, the Standard Model has certain shortcomings which have driven particle physicists for the last 30 years to search for phenomena which provide evidence for the next theory beyond the Standard Model. To this end, using the BaBar detector, we search for evidence of the rare decay D^*+ → D⁰π⁺; D⁰ → γγ. The branching fraction of this decay is enhanced up to 200 times the standard model prediction in certain beyond-the-Standard-Model theories. A measurement of a significant branching fraction would provide evidence for a new theory of particle physics. We describe our search for this rare decay and an improved measurement of the associated decay, 𝓑(D⁰ → π⁰π⁰) using an integrated luminosity corresponding to 470.5fb^-1 of e⁺e^- data collected by the BaBar detector at the PEP-II asymmetric e⁺e^- collider at SLAC from 1999-2007. We place an upper limit of

𝓑(D⁰ → γγ) < 2.51 × 10^-6

at 90% confidence level and find

𝓑(D⁰ → π⁰π⁰) = (8.4 ± 0.1 ± 0.4 ± 0.3) × 10^-4.