Lorentz-Violating Massive Gravity in Curved Space

Understand

In models of modified gravity, extra degrees of freedom usually appear.

• They must be removed from the spectrum because they may indicate the presence of instabilities and because otherwise the model might not agree with observation.
• In the present letter, we will discuss a model that modifies General Relativity through the addition of a Lorentz-violating potential-like term for the metric.
• No additional propagating modes and no classical instabilities are present.