EAGER: IMPRESS-U: Two-body Currents in Relativistic Electron and Neutrino Scattering off Few-nucleon Targets

University Of Iowa, Iowa City IA

Investigators

Abstract

This EAGER IMPRESS-U project is jointly supported by NSF, US National Academy of Sciences, Office of Naval Research Global (DoD), and National Science Centre of Poland. The research will be conducted in collaborative partnership that unites the University of Iowa (US), Jagiellonian University (Poland), Kharkiv Institute of Physics and Technology (Ukraine), Karazin Kharkiv National University (Ukraine), Kharkiv Institute of Physics and Technology (Ukraine), and Kyushu Institute of Technology (Japan). The US portion of this EAGER IMPRESS-U project is co-funded by NSF Office of International Science and Engineering and MPS/PHY. A precise understanding of how neutrinos interact with nuclei provides a sensitive tool to investigate physics beyond the standard model. The neutrino-nuclear system is described by a Hamiltonian that includes interactions involving both nucleons and neutrinos. For neutrino energies near or above a billion electron volts the structure of this Hamiltonian is constrained by special relativity. The publication record of the PI and collaborators from Poland and Ukraine includes relativistic calculations of electrons and neutrinos scattering off of light nuclei. The PI and collaborators are investigating the structure of the Hamiltonian for a neutrino interacting with a Deuteron (the simplest nucleus). The least understood part of this Hamiltonian is an interaction that simultaneously involves the neutrino and both nucleons, which is expressed in terms of a ”two-nucleon current”. The goal of this collaboration is to determine a two-nucleon current that is consistent with the nuclear Hamiltonian. The collaboration supports graduate students in Poland and Ukraine and a post doc in neutrino physics. It sustains the physics infrastructure in Ukraine at this very challenging time. The scientific goal of this project is to construct a two-nucleon-neutrino current to use in relativistic neutrino-nucleus scattering calculations. The current is constructed using a transformation, advocated by the Ukrainian members of the collaboration, that transforms the Hamiltonian of a quantum field theory of nucleons and neutrinos to a Hamiltonian for a system of interacting stable particles. The same transformation is used to compute the corresponding two-nucleon electromagnetic current. A consistent model must provide a precise understanding of both electron and neutrino scattering from Deuterons. Both two-body currents have a similar structure but there is more data to constrain the electromagnetic current. The outcome of this project are comparisons of neutrino and electron – Deuteron scattering calculations to experiment, the determination of the contribution of the two-body currents to different scattering observables, and predictions of neutrino and electron scattering observables. While the calculation are for electron and neutrino-Deuteron scattering, both two-body currents appear in Hamiltonians for larger nuclei . This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.