A keV String Axion from High Scale Supersymmetry

Understand

Various theoretical and experimental considerations motivate models with high scale supersymmetry breaking.

• While such models may be difficult to test in colliders, we propose looking for signatures at much lower energies.
• We show that a keV line in the X-ray spectrum of galaxy clusters (such as the recently disputed 3.5 keV observation) can have its origin in a universal string axion coupled to a hidden supersymmetry breaking sector.
• A linear combination of the string axion and an additional axion in the hidden sector remains light, obtaining a mass of order 10 keV through supersymmetry breaking dynamics.