Tension Between a Vanishing Cosmological Constant and Non-Supersymmetric Heterotic Orbifolds

Understand

We investigate under which conditions the cosmological constant vanishes perturbatively at the one-loop level for heterotic strings on non-supersymmetric toroidal orbifolds.

• To obtain model-independent results, which do not rely on the gauge embedding details, we require that the right-moving fermionic partition function vanishes identically in every orbifold sector.
• This means that each sector preserves at least one, but not always the same Killing spinor.
• The existence of such Killing spinors is related to the representation theory of finite groups, i.e.