Abstract
The thermal plasma filling the early universe generated a stochasticgravitational wave background that peaks in the microwave frequencyrange today. If the graviton production rate is expressed as a series in afine-structure constant, α, and the temperature over the Planck mass, T 2/m pl 2, then the lowest-order contributions come from single(∼αT 2/m pl 2) and double (∼T 4/m pl 4)graviton production via 2 → 2 scatterings.We show that in the Standard Model,single-graviton production dominates if the maximaltemperature is smaller than4 × 1018 GeV. This justifies previous calculationswhich relied solely on single-graviton production.We mention Beyond the Standard Model scenarios in which the single anddouble-graviton contributions could be of comparable magnitudes.Finally, we elaborate on what these results imply for the range ofapplicability of General Relativity as an effective theory.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
