Nitish Nayak (University of California, Irvine) “Ghostbusters : Estimation of Neutrino Oscillation Parameters by the NOvA Experiment”

The discovery of neutrino oscillations provides the first indication of a lepton flavor violating (LFV) process, one that isn’t predicted by the Standard Model. Extending the Standard Model picture to account for this usually proceeds via the addition of new mass terms, either Dirac or Majorana in nature or both, to the Standard Model Lagrangian. Probing the LFV process by characterizing the strength of neutrino oscillations is therefore fundamental to understanding the nature of neutrino masses. In addition, there is a possibility that neutrino oscillations are CP-violating which can provide hints about the observed matter-antimatter asymmetry in the universe. The NOvA experiment at Fermilab was designed to be sensitive to such questions by measuring some of the key parameters governing oscillatory behaviour. It detects neutrinos (antineutrinos) using an intense beam of predominantly muon-neutrinos (muon-antineutrinos) from the NuMI facility at Fermilab. It does this by housing two detectors, a 1-kiloton Near Detector near the beam source and a massive 14-kiloton Far Detector, 810 km away, near the Canadian border. The measurement of neutrino oscillation parameters is performed by examining the neutrino beam and the simulation at the Near Detector and then observing how many neutrinos have oscillated by the time they reach the Far Detector. This is a challenging analysis highlighted by the fact that only a handful of oscillated events are observed at the Far Detector every year. This is made worse by the fact that the Far Detector is placed on the surface, thus collecting an enormous amount of cosmic background (at a rate of $\sim$ 10 kHz). In this talk I will therefore provide an overview of how this measurement is performed and some of the key problems we wrestle with. These problems can be statistical, computational and even theoretical and so I will put particular emphasis on the methodologies used in overcoming them.