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arXiv · 2109.08166

CFTs Blueshift Tensor Fluctuations Universally

Matthew Baumgart·Jonathan J. Heckman·Logan Thomas
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Abstract

The strong constraints of conformal symmetry cause any nearly-conformal sector to blueshift tensor fluctuations in cosmology. Hidden sectors with approximate conformal symmetry, which may be quite large, are a well-motivated extension of physics beyond the Standard Models of particle physics and cosmology. They can therefore lead to a detectable shift in the tensor tilt for next-generation CMB and gravitational wave experiments. We compute the leading-order contribution to the in-in graviton two-point function from virtual loops in such sectors to demonstrate this universal effect. In units where a single conformally-coupled scalar is 1, limits from Stage-IV CMB experiments could bound the size of this extra sector to be smaller than about 10^15. This would be sufficient to rule out N-Naturalness as a complete resolution of the hierarchy problem.

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Matthew Baumgart, Jonathan J. Heckman, Logan Thomas. 2021-09-16. CFTs Blueshift Tensor Fluctuations Universally. https://doi.org/10.1088/1475-7516/2022/07/034

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