Isospin violating dark matter in St\"uckelberg portal scenarios

Understand

Hidden sector scenarios in which dark matter (DM) interacts with the Standard Model matter fields through the exchange of massive Z' bosons are well motivated by certain string theory constructions.

• In this work, we thoroughly study the phenomenological aspects of such scenarios and find that they present a clear and testable consequence for direct DM searches.
• We show that such string motivated St\"uckelberg portals naturally lead to isospin violating interactions of DM particles with nuclei.
• We find that the relations between the DM coupling to neutrons and protons for both, spin-independent (fn/fp) and spin-dependent (an/ap) interactions, are very flexible depending on the charges of the quarks under the extra U(1) gauge groups.