Evading the pulsar constraints on the cosmic string tension in supergravity inflation

TL;DR

This paper proposes a supergravity inflation model that allows observable cosmic strings in the CMB while avoiding pulsar timing constraints by delaying the scaling regime.

Contribution

It introduces a scenario within supergravity inflation where cosmic strings with large tension can exist without conflicting with pulsar constraints.

Findings

Cosmic strings can be observable in the CMB despite pulsar constraints.

Delaying the onset of the scaling regime allows larger string tensions.

The scenario is naturally realized in chaotic inflation models in supergravity.

Abstract

The cosmic string is a useful probe of the early Universe and may give us a clue to physics at high energy scales where any artificial particle accelerators cannot reach. Although one of the most promising tools is the cosmic microwave background, the constraint from gravitational waves is becoming so stringent that one may not hope to detect its signatures in the cosmic microwave background. In this paper, we construct a scenario that contains cosmic strings observable in the cosmic microwave background while evading the constraint imposed by the recent pulsar timing data. We argue that cosmic strings with relatively large tension are allowed by delaying the onset of the scaling regime. We also show that this scenario is naturally realized in the context of chaotic inflation in supergravity, where the phase transition is governed by the Hubble induced mass.