Large-scale magnetic fields from inflation due to Chern-Simons-like effective interaction

We discuss the generation of large-scale magnetic fields due to the breaking of the conformal invariance in the electromagnetic field through the $CPT$-even dimension-six Chern-Simons-like effective interaction with a fermion current in inflationary cosmology. It is shown that the magnetic fields on 1Mpc scale with the field strength of $\sim 10^{-9}$G at the present time can be generated even for the scale of the effective interaction being the Planck scale.Comment: 13 pages, 2 figures, additional explanations include

Gravitational wave production by collisions: more bubbles

We re-examine the production of gravitational waves by bubble collisions during a first-order phase transition. The spectrum of the gravitational radiation is determined by numerical simulations using the 'envelope approximation'. We find that the spectrum rises as f3.0 for small frequencies and decreases as f-1.0 for high frequencies. Thus, the fall-off at high frequencies is significantly slower than previously stated in the literature. This result has direct impact on detection prospects for gravity waves originating from a strong first-order electroweak phase transition at space-based interferometers, such as LISA and BBO. In addition, we observe a slight dependence of the peak frequency on the bubble wall velocity