Analytic infinite derivative gravity, $R^2$-like inflation, quantum gravity and CMB

TL;DR

This paper explores how $R^2$ inflation, linked to quantum gravity and trace anomalies, can serve as a probe for non-locality signatures in the early Universe, with implications for CMB observations.

Contribution

It connects $R^2$ inflation with non-local quantum gravity frameworks and discusses potential observational signatures in the CMB.

Findings

Embedding $R^2$ inflation in non-local gravity models yields testable predictions.

Non-locality at small scales may leave imprints on CMB data.

Theoretical models suggest a link between quantum gravity effects and inflationary signatures.

Abstract

Emergence of $R^2$ inflation which is the best fit framework for CMB observations till date comes from the attempts to attack the problem of quantization of gravity which in turn have resulted in the trace anomaly discovery. Further developments in trace anomaly and different frameworks aiming to construct quantum gravity indicate an inevitability of non-locality in fundamental physics at small time and length scales. A natural question would be to employ the $R^2$ inflation as a probe for signatures of non-locality in the early Universe physics. Recent advances of embedding $R^2$ inflation in a string theory inspired non-local gravity modification provides very promising theoretical predictions connecting the non-local physics in the early Universe and the forthcoming CMB observations.