Invisible Upsilon decays into Light Dark Matter

Understand

Invisible psi and Upsilon decays into light neutralinos, within the MSSM or N(n)MSSM, are smaller than for nu nubar production, even if light spin-0 particles are coupled to quarks and neutralinos.

• In a more general way, light dark matter particles are normally forbidden, unless they can annihilate sufficiently through a new interaction stronger than weak interactions (at lower energies), as induced by a light spin-1 U boson, or heavy-fermion exchanges in the case of scalar dark matter.
• We discuss the possible contributions of U-boson, heavy-fermion, or spin-0 exchanges to invisible psi and Upsilon decays.
• U-exchanges could lead, but not necessarily, to significant branching fractions for invisible decays into light dark matter.