We point out that string theory can solve the conundrum to explain the
emergence of an electroweak dipole moment from electroweak singlets through
induction of those dipole moments through a Kalb-Ramond dipole coupling. This
can generate a U_Y(1) portal to dark matter and entails the possibility that
the U_Y(1) gauge field is related to a fundamental vector field for open string
interactions. The requirement to explain the observed dark matter abundance
relates the coupling scale in the corresponding low-energy effective U_Y(1)
portal to the dark matter mass. The corresponding electron recoil cross
sections for a single dipole coupled dark matter species are generically below
the current limits from XENON, SuperCDMS and SENSEI, except in the GeV mass
range if the electric dipole coupling becomes stronger than the magnetic
coupling. Furthermore, the recoil cross sections are above the neutrino floor
and the U_Y(1) portal can be tested with longer exposure or larger detectors.
Discovery of electroweak dipole dark matter would therefore open an interesting
window into string phenomenology.Comment: 8 pages, 2 figures. v3 also discusses the effects of an electric
dipole coupling on electron recoils, in addition to the magnetic dipole
couplin
