Positivity vs. Lorentz-violation: an explicit example

We show how a class of multi-field scalar-field theories in a Lorentz-breaking background imposes consistency conditions on its effective theory of a single field and provides an example of order-unity violation of a naively applied positivity bound, assuming a large hierarchy between the masses of the lightest field and the others.

Automated summary

In a Lorentz-breaking background, a class of multi-field scalar-field theories imposes consistency conditions on its effective theory of a single field, demonstrating an example of order-unity violation of a naively applied positivity bound when a large hierarchy exists between the masses of the lightest field and the others.