LABORATORI NAZIONALI DI FRASCATI
Speaker: Bogdan Wojtsekhowski (JLab) A search was done by using electro-production of a heavy photon (A’) in electron scattering from W nuclei with following decay to an electron-positron pair. The experiment was performed at Hall A of Jefferson Lab using a 2.1 GeV beam and collected statistics for a search sensitivity of 0.1 ppm (relative to the coupling of an EM photon). Such a sensitivity is about 10 times better than known from currently published experiments for the A’ mass near 200 MeV. The experiment and preliminary analysis of the data quality will be presented. In the second part of this talk, I will discuss the search for A’ in an inverse reaction with a positron-electron annihilation which has an important advantage of being independent of the A’ decay. The experiment for the mass range above 70 MeV requires a novel experimental technique because typical colliders with cm energy below 500 MeV have insufficient luminosity. The concept of a Very Asymmetric Collider is based on a low energy electron beam accelerator and a high energy positron storage ring. Such a configuration allows us to boost the luminosity to the level of 10$^{34}$ 1/cm$^2$/s.

DATA: 20-09-2019