M1/M2 : Global parametric fits of solar neutrino oscillation data

Neutrinos are the lightest massive fundamental particles in the universe. The discovery of neutrino flavour oscillations (where neutrinos will change particle type as they propagate through space) by the Super-Kamiokande and SNO experiments, in 1998 and 2001, respectively, was one of the most important developments in contemporary particle physics. Still today, new experiments such as DUNE, JUNO and Hyper-Kamiokande are making precise measurements of these oscillations.

Neutrino oscillations are observed (primarily) in four regimes: in man-made neutrinos coming from nuclear reactors, in neutrinos produced at particle accelerators, in neutrinos coming from the impact of cosmic rays in the atmosphere and in neutrinos emitted by the sun. These solar neutrinos are extremely abundant, and measuring how the electron-type neutrinos disappear into other types offers a rich probe of oscillation physics.

The neutrino group at LAPP, in its involvement with the DUNE experiment, has taken a pivotal role in developing the framework for measuring the solar neutrino oscillation parameters. At the present time, the most stringent constraints come from phenomenologist-led global fits, which attempt to combine the theoretical predictions and the different measurements by approximating the experimental conditions (e.g. energy resolution).

Now that we are entering the era of precision measurements in neutrino oscillations, the limitations of such global fits (namely, that they must assume the experimental responses and their correlations) are becoming more relevant. Luckily, benchmark solar neutrino experiments (SNO, Super-Kamiokande) also publish model-agnostic parametric fits of the oscillation probabilities, which may be used in a more robust, but less powerful, global fit. The intern’s role would be to adapt the neutrino oscillation fitter developed at LAPP in order to include the published experimental parametric neutrino oscillation probabilities. In this way, they would produce a model-agnostic global constraint fit for publication. In more detail, the intern would be expected to code a term in the χ2 including the vector of coefficients from the parametric fit, and its covariance matrix (both given by current experiments).

Otherwise, most of the work will come from the intern becoming familiar with fitting methods for neutrino oscillation data, a statistics and physics-heavy topic useful to any prospective particle physicist, with the benefit of a possible publication at the end of the road.

Informations:

Expérience: DUNE

Responsable de stage: Andres Lopez Moreno

Email: andres.lopezmoreno@lapp.in2p3.fr