Dark matter direct detection via electromagnetic multipoles

by Merlin Reichard (Technical University of Munich)

Wednesday 21 Jun 2023, 16:00 → 17:30 Asia/Seoul

1423 in building 1 (KIAS)

Title: Dark matter direct detection via electromagnetic multipoles

Speaker: Merlin Reichard (Technical University of Munich)

Abstract: Albeit typically considered to be "dark", a dark matter particle can interact electromagnetically with ordinary matter via higher multipole moments generated at the quantum level. If dark matter particles are of Dirac nature, only a millicharge, an electric- and magnetic dipole, and an anapole moment can exist. If, however, it is a Majorana fermion---as naturally predicted by some BSM theories such as the MSSM---the only allowed electromagnetic moment is the anapole moment. After recapitulating the electromagnetic moments within classical electrodynamics, I will discuss their role for neutral particles within a relativistic field theory description. Further, I will discuss generating these moments via pairs of scalar-fermion or vector-fermion at the one-loop level within a toy model, focusing on the anapole moment of a Majorana fermion. Here I will highlight the need for the background field method to address the gauge-dependent triple gauge vertex adequately. Based on these general results, I will present the predictions for the anapole moment of the lightest neutralino within simplified models and the MSSM and contrast them with limits from direct detection experiments. Finally, I will discuss the model predictions for the dipole moments of a Dirac DM candidate within a toy model and show that current-generation of direct detection experiments strongly constrain the parameter space corresponding to a thermal relic.