Cosmic Strings and the String Dilaton

TL;DR

The paper investigates how the presence of a dilaton field affects the permissible energy scale of cosmic strings, deriving constraints based on dilaton mass and coupling strength, with implications for cosmological models.

Contribution

It provides new bounds on cosmic string energy scales considering dilaton interactions, highlighting conditions under which superheavy strings are ruled out or allowed.

Findings

Superheavy gauge strings are ruled out if dilaton mass is below 100 TeV.

For a dilaton mass around 1 TeV, the string energy scale must be below approximately 3×10^{11} GeV.

Certain non-standard cosmological scenarios can evade these constraints.

Abstract

The existence of a dilaton (or moduli) with gravitational-strength coupling to matter imposes stringent constraints on the allowed energy scale of cosmic strings, $\eta$. In particular, superheavy gauge strings with $\eta \sim 10^{16} GeV$ are ruled out unless the dilaton mass $m_{\phi} \gsim 100 TeV$, while the currently popular value $m_{\phi} \sim 1 TeV$ imposes the bound $\eta \lsim 3 \times 10^{11} GeV$. Similar constraints are obtained for global topological defects. Some non-standard cosmological scenarios which can avoid these constraints are pointed out.