Pulsar Timing Constraints on Physics Beyond the Standard Model

TL;DR

This paper demonstrates that pulsar timing data can constrain the mass of hypothetical particles, limiting new physics models below the quantum gravity scale by linking quantum field fluctuations to observable spacetime curvature variations.

Contribution

It introduces a gauge-invariant observable connecting quantum stress-energy fluctuations to pulsar timing measurements, providing novel astrophysical constraints on beyond Standard Model particles.

Findings

Massive particles are constrained to be lighter than approximately 600 GeV.

Current pulsar timing data severely restricts new physics models below the quantum gravity scale.

The approach links quantum field fluctuations to observable spacetime curvature on the lightcone.

Abstract

We argue that massive quantum fields source low-frequency long-wavelength metric fluctuations through the quantum fluctuations of their stress-energy, given reasonable assumptions about the analytic structure of its correlators. This can be traced back to the non-local nature of the gauge symmetry in General Relativity, which prevents an efficient screening of UV scales (what we call the cosmological non-constant problem). We define a covariant and gauge-invariant observable which probes line-of-sight spacetime curvature fluctuations on an observer's past lightcone, and show that current pulsar timing data constrains any massive particle to $m\lesssim 600$ GeV. This astrophysical bound severely limits the possibilities for physics beyond the standard model below the scale of quantum gravity.