Speaker
Description
Experiments using positron beams impinging on fixed targets offer unique capabilities for probing new light dark particles feebly coupled to e^+ e^- pairs, that can be resonantly produced from positron annihilation on target atomic electrons. In this talk, I will discuss the impact of correctly accounting for the momentum distribution of the atomic electrons that shifts the center of mass energy of the annihilating e+e- pairs, and that must be taken into account in the determination of the number of signal events. After discussing how to reliably compute the cross section for the process, I will show how to obtain the bound electron momentum distribution for different target materials from theoretical computations or experimental data. Finally, I will apply these results to the search for the hypothetical X17 particle focusing on the expected reach of the PADME experiment.
