Search for a "Dark Photon" with the Mainz Microtron

Harald Merkel (Mainz)
DESY Auditorium, 16.00 h

Nearly all consistent extensions of the Standard Model predict an additional U(1) interaction, which comes in naturally as lowest-rank symmetry due to the breaking of large symmetries. Such an interaction is carried by a U(1) boson with very weak interaction with Standard Model matter, sometimes called the "Dark Photon".
Some existing indirect experimental evidence for deviations from the Standard Model can be explained by such an additional interaction, e.g. the g-2 anomaly of the muon or the heavily disputed result of the DAMA/LIBRA dark matter search experiment, which suggests a mass range for the dark photon up to ~1 GeV.
The direct search for such a dark photon requires luminosities far beyond existing experiments in combination with excellent mass resolution to access the region of the expected very weak coupling. Ideal for this task are the high external current electron accelerators for fixed target electro-production experiments. In this talk, a first test measurement at the Mainz Microtron (MAMI) will be presented, which shows the quality and discovery potential of this new measurement principle.

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