Gravitational waves induced by spinor fields

Understand

In realistic model-building, spinor fields with various masses are present.

• During inflation, spinor field may induce gravitational waves as a second order effect.
• In this paper, we calculate the contribution of single massive spinor field to the power spectrum of primordial gravitational wave by using retarded Green propagator.
• We find that the correction is scale-invariant and of order $H^4/M_P^4$ for arbitrary spinor mass $m_{\psi}$.