Chiral Primordial Gravitational Waves from a Lifshitz Point
  We study primordial gravitational waves produced during inflation in quantum
gravity at a Lifshitz point proposed by Ho${\rm\check{r}}$ava. Assuming
power-counting renormalizability, foliation preserving diffeomorphism
invariance, and the condition of detailed balance, we show that primordial
gravitational waves are circularly polarized due to parity violation. The
chirality of primordial gravitational waves is a quite robust prediction of
quantum gravity at a Lifshitz point which can be tested through observations of
cosmic microwave background radiation and stochastic gravitational waves.
