DarkLight@ARIEL: A Search for New Physics and the foundation of an electron scattering program at ARIEL/TRIUMF

DarkLight@ARIEL: A Search for New Physics and the foundation of an electron scattering program at ARIEL/TRIUMF Jan C. Bernauer, Stony Brook University, Center for Frontiers in Nuclear Physics, Department for Physics and Astronomy, Stony Brook, NY, 11794, USA and RIKEN BNL Research Center, Upton, NY, 11973, USA  (Principal Investigator) The Standard Model is our canonical theory describing three out of the four fundamental forces and describing all elementary particles. However, we know that it is not complete. DarkLight@ARIEL seeks to find physics beyond the Standard Model, by scattering an intense 30-50 MeV electron beam off a tantalum target. In this reaction, a possible new particle could be produced momentarily, to decay into an electron-positron pair. The experiment is designed to measure these pairs with two magnetic spectrometers and reconstruct the mass of the new particle. The search range 10-20 MeV is motivated by recent anomalies detected in the decay of excited Be-8, He-4, and C-12 atoms which could be explained by a new, fifth force mediated by a new particle around 17 MeV.Such a particle could provide a gateway to study the elusive so-called dark sector, something we know little about except that it makes up about 75% of the gravitational mass in our universe. ARIEL is a new accelerator facility at the TRIUMF research laboratory in Vancouver, Canada. The grant supports the work of PI Dr. Bernauer and his group on DarkLight@ARIEL, an international collaboration with members from the USA, Canada, and Germany. The experiment setup constructed as part of the DarkLight experiment will be the foundation of a wide electron scattering program at ARIEL.