# Effects of QCD Equation of State on the Stochastic Gravitational Wave Background

## TL;DR

This paper investigates how the QCD equation of state, including lattice QCD trace anomaly effects, influences the spectrum of stochastic gravitational waves generated during the QCD phase transition, revealing a significant enhancement and frequency shift.

## Contribution

It provides the first detailed calculation of the SGW spectrum incorporating lattice QCD results, showing notable modifications to the expected signal.

## Key findings

- SGW signal during QCD transition is enhanced by ~50%.
- Peak frequency of SGW shifts higher by ~25%.
- Results are crucial for testing QCD epoch phase transition models.

## Abstract

Cosmological phase transitions can be a source of Stochastic Gravitational Wave (SGW) background. Apart from the dynamics of the phase transition, the characteristic frequency and the fractional energy density $\Omega_{\rm gw}$ of the SGW depends upon the temperature of the transition. In this article, we compute the SGW spectrum in the light of QCD equation of state provided by the lattice results. We find that the inclusion of trace anomaly from lattice QCD, enhances the SGW signal generated during QCD phase transition by $\sim 50\%$ and the peak frequency of the QCD era SGW are shifted higher by $\sim 25\%$ as compared to the earlier estimates without trace anomaly. This result is extremely significant for testing the phase transition dynamics near QCD epoch.