# Solid Consistency

## TL;DR

This paper demonstrates that in solid inflation, scalar fluctuations are adiabatic on super-horizon scales, leading to specific consistency relations for correlation functions that are independent of the model's detailed dynamics.

## Contribution

It shows that scalar fluctuations in solid inflation are adiabatic at large scales and establishes the validity of Maldacena's consistency relation in this context.

## Key findings

- Adiabatic scalar fluctuations in solid inflation persist on super-horizon scales.
- Maldacena's squeezed limit consistency relation holds after angular averaging.
- Correlation functions are determined by the scaling of short modes, regardless of the inflationary action.

## Abstract

We argue that $isotropic$ scalar fluctuations in solid inflation are adiabatic in the super-horizon limit. During the solid phase this adiabatic mode has peculiar features: constant energy-density slices and comoving slices do not coincide, and their curvatures, parameterized respectively by $\zeta$ and $\mathcal R$, both evolve in time. The existence of this adiabatic mode implies that Maldacena's squeezed limit consistency relation holds after angular average over the long mode. The correlation functions of a long-wavelength spherical scalar mode with several short scalar or tensor modes is fixed by the scaling behavior of the correlators of short modes, independently of the solid inflation action or dynamics of reheating.