Abstract
The thermal plasma filling the early universe generated a stochastic gravitational wave background that peaks in the microwave frequency range today. If the graviton production rate is expressed as a series in a fine-structure constant, α, and the temperature over the Planck mass, T2/mpl2, then the lowest-order contributions come from single (∼αT2/mpl2) and double (∼T4/mpl4) graviton production via 2 → 2 scatterings. We show that in the Standard Model, single-graviton production dominates if the maximal temperature is smaller than 4 × 1018 GeV. This justifies previous calculations which relied solely on single-graviton production. We mention Beyond the Standard Model scenarios in which the single and double-graviton contributions could be of comparable magnitudes. Finally, we elaborate on what these results imply for the range of applicability of General Relativity as an effective theory.
Export citation and abstract BibTeX RIS
Published by IOP Publishing Ltd on behalf of Sissa Medialab. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.