Speaker
Luca Marsicano
(INFN Genova)
Description
The interest in the Dark Photon (A' or U) has recently grown, since it could act as a light mediator to a new sector of Dark Matter particles. In this paradigm, the electron-positron annihilation can rarely produce a $\gamma $ U couple. Various experiments (e.g. PADME@LNF, Adv. High Energy Phys. 2014:959802; VEPP-3, arXiv:1207.5089[hep-ex]) have been proposed to detect this process using positron beams impinging on fixed targets. In such experiments, the energy of the photon from the $e^+ e^- \rightarrow \gamma U$ process is measured with an electromagnetic calorimeter and the missing mass is computed (the U interacts weakly with Standard Model matter so it can't be detected). However, the U mass range that can be explored with this technique is limited by the accessible energy in the center of mass frame, which goes as the square root of the beam energy.
The realization of a 11 GeV positron beam at Jefferson Lab would allow to search for U masses up to $\sim$100 MeV, reaching unexplored regions of the U parameter space. A preliminary study on the feasibility of a PADME-like experiment at Jefferson Lab has been carried out, assuming a 11 GeV positron beam with a $\sim \mu$A current. The achievable sensitivity was estimated, studying the main sources of background (positron Bremsstrahlung, annihilation into 2 gammas) using CALCHEP and GEANT4 simulations.
Primary author
Luca Marsicano
(INFN Genova)
