Speaker
Description
A search for sub-GeV dark matter (DM) will be performed by the DarkMESA experiment behind the beam dump of the MESA external electron beam in Mainz, Germany. Various dark sector models motivate the existence of sub-GeV scalar and Majorana or pseudo-Dirac DM, accessible in this type of beam-dump experiment, e.g. by coupling to a dark photon mediator $A'$. In the presence of light DM in the dark sector with masses $m_\chi < m_A'/2,$, the $A'$ would predominantly decay invisibly into those $\chi$ particles provided that the dark coupling constant $\alpha_D$ is not too small. Re-interpretations of null results in a multitude of other models are possible [1].
The experiment makes use of the high intensity electron beam available at MESA and will run parasitically to the scheduled program with the P2 apparatus. The experiment is based on a solid and reliable detection technology and will collect an unprecedented accumulated charge in a few years time, that will extend current limits on light DM [2].
[1] G. Lanfranchi et al., Feebly-Interacting Particles: FIPs 2020 Workshop Report (2020), arXiv:2102.12143.
[2] M. Christmann et al., Instrumentation and optimization studies for a beam dump experiment (BDX) at MESA $-$ DarkMESA, Nucl. Instrum. Meth. Phys. Res. A 958 (2020) 162398, DOI:10.1016/j.nima.2019.162398.
