CFTs blueshift tensor fluctuations universally
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 physic...
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Published in | Journal of cosmology and astroparticle physics Vol. 2022; no. 7; pp. 34 - 58 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Bristol
IOP Publishing
01.07.2022
Institute of Physics (IOP) |
Subjects | |
Online Access | Get full text |
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Summary: | 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 ∼10
15
, under a
plausible calculational assumption backed by a simple power counting
argument. This would be sufficient to rule out N-Naturalness as a
complete resolution of the hierarchy problem. |
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Bibliography: | USDOE Office of Science (SC), High Energy Physics (HEP) SC0019470 |
ISSN: | 1475-7516 1475-7516 |
DOI: | 10.1088/1475-7516/2022/07/034 |