Heavy Particle Beyond Standard Model Physics Is Limited

by Tommy on 8/04/2017

This should give any MACHO WIMPS pause for thought.


Pulsar Timing Constraints on Physics Beyond the Standard Model, Niayesh Afshordi, Hyungjin Kim and Elliot Nelson (15 March 2017)

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 ≲ 600 GeV. This astrophysical bound severely limits the possibilities for physics beyond the standard model below the scale of quantum gravity.

This new empirical prediction seems to be in direct conflict with their previous post-Higgs, pre-upgraded-LHC theoretical prediction of imminent TeV scale physics. Fortunately, the cosmic QCD ‘gravitational’ axion is exempt from this. That prediction was archived here for posterity.



Cosmological bounds on TeV-scale physics and beyond, Niayesh Afshordi and Elliot Nelson, Phys. Rev. D 93, 083505 (7 April 2016), DOI:10.1103/PhysRevD.93.083505

We study the influence of the fluctuations of a Lorentz invariant and conserved vacuum on cosmological metric perturbations, and show that they generically blow up in the IR. We compute this effect using the Källén-Lehmann spectral representation of stress correlators in generic quantum field theories, as well as the holographic bound on their entanglement entropy, both leading to an IR cut-off that scales as the fifth power of the highest UV scale (in Planck units). One may view this as analogous to the Heisenberg uncertainty principle, which is imposed on the phase space of gravitational theories by the Einstein constraint equations. The leading effect on cosmological observables come from anisotropic vacuum stresses which imply: i) any extension of the standard model of particle physics can only have masses (or resonances) ≲ 24 TeV, and ii) perturbative quantum field theory or quantum gravity becomes strongly coupled beyond a cut-off scale of Λ ≲ 1 PeV. Such a low cut-off is independently motivated by the Higgs hierarchy problem. This result, which we dub the cosmological non-constant problem, can be viewed as an extension of the cosmological constant (CC) problem, demonstrating the non-trivial UV-IR coupling and (yet another) limitation of effective field theory in gravity. However, it is more severe than the old CC problem, as vacuum fluctuations cannot be tuned to cancel due to the positivity of spectral densities or entropy. We thus predict that future advances in cosmological observations and collider technology will sandwich from above and below, and eventually discover, new (non-perturbative) physics beyond the Standard Model within the TeV-PeV energy range.

This was in the 750 GeV bump era, so it appears the sandwich has closed.

The empirical prediction seems more persuasive.


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