# Lorentz Violating Field

1. Apr 4, 2008

### robousy

Hey folks,

I'm reading a paper by Sean Carroll (http://arxiv.org/PS_cache/arxiv/pdf/0802/0802.0521v1.pdf [Broken]).

In the paper he refers to a Lorentz violating background

$$u^a=(0,0,0,0,v)$$

$$S=M_*\int d^5x \sqrt{g} \left[-\frac{1}{4}(\nabla_a u_b -\nabla_b u_a)(\nabla^a u^b -\nabla^b u^a)-\lambda(u_au^a-v^2)+\sum_{i=1}^{2} \mathcal{L}_i\right].$$

Can anyone interpret this action?? Also, can anyone explain why the field is Lorentz invariant??