As the age of WIMP-scale dark matter (DM) draws to a close thanks to the ever-increasing sensitivity of direct detection experiments, the majority of sub-GeV DM parameter space remains to be explored. Sub-GeV DM can excite electronic transitions in a variety of molecular and nano-scale systems which have sub-eV scale thresholds. In particular, organic molecules, nanoparticles, and solvated electrons can be used to detect the low momentum recoils of dark matter with electrons and nuclei. Aromatic molecules such as benzene or xylene have an electronic excitation energy of a few eV, making them sensitive to DM as light as a few MeV. These compounds are often used as solvents in organic scintillators, where the de-excitation process leads to a photon which propagates until it is absorbed and re-emitted by a dilute fluor whose emission is not absorbed by the bulk and thus reaches a photomultiplier tube (PMT), Here,we develop the formalism for DM-electron scattering in aromatic organic molecules, calculate the expected sensitivity to DM-electron scattering in benzene and p-xylene, and apply this calculation to EJ-301.
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