Tensor bounds on the hidden universe
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During single clock inflation, hidden fields (i.e. fields coupled to the inflaton only gravitationally) in their adiabatic vacua can ordinarily only affect observables through virtual effects. After renormalizing background quantities (fixed by observations at some pivot scale), all that remains are logarithmic runnings in correlation functions that are both Planck and slow roll suppressed. In this paper we show how a large number of hidden fields can partially compensate this suppression and generate a potentially observable running in the tensor two point function, consistently inferable courtesy of a large N resummation. We detour to address certain subtleties regarding loop corrections during inflation, extending the analysis of . Our main result is that one can extract bounds on the hidden field content of the universe from bounds on violations of the consistency relation between the tensor spectral index and the tensor to scalar ratio, were primordial tensors ever detected. Such bounds are more competitive than the naive bound inferred from requiring inflation to occur below the strong coupling scale of gravity if deviations from the consistency relation can be bounded to within the sub-percent level. We discuss how one can meaningfully constrain the parameter space of various phenomenological scenarios and constructions that address naturalness with a large number of species (such as ‘N-naturalness’) with CMB observations up to cosmic variance limits, and possibly future 21cm and gravitational wave observations.
KeywordsCosmology of Theories beyond the SM Renormalization Regularization and Renormalons
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- A.H. Guth, The inflationary universe: a possible solution to the horizon and flatness problems, Phys. Rev. D 23 (1981) 347 [INSPIRE].
- A.D. Linde, A new inflationary universe scenario: a possible solution of the horizon, flatness, homogeneity, isotropy and primordial monopole problems, Phys. Lett. B 108 (1982) 389.Google Scholar
- V.F. Mukhanov and G.V. Chibisov, Quantum fluctuations and a nonsingular universe, JETP Lett. 33 (1981) 532 [Pisma Zh. Eksp. Teor. Fiz. 33 (1981) 549] [INSPIRE].
- A. del Rio, R. Durrer and S.P. Patil, in preparation.Google Scholar
- N.D. Birrell and P.C.W. Davies, Quantum fields in curved space,Cambridge Monogr. Math. Phys., Cambridge University Press (1984).Google Scholar
- V.F. Mukhanov, Physical foundations of cosmology, Cambridge University Press, Cambridge U.K. (2005).Google Scholar
- R. Durrer, The Cosmic Microwave Background, Cambridge University Press, Cambridge U.S.A. (2008).Google Scholar
- S. Weinberg, Cosmology, Oxford University Press, Oxford U.K. (2008).Google Scholar
- P. Adshead, private communication.Google Scholar