Suppression of Electroweak Instanton Processes in High-energy Collisions

Abstract

Electroweak instantons are a prediction of the Standard Model and have been studied in great detail in the past although they have not been observed. Earlier calculations of the instanton production cross section at colliders revealed that it was exponentially suppressed at low energies, but may grow large at energies (much) above the sphaleron mass. Such calculations faced difficulty in the breakdown of the instanton perturbation theory in the high-energy regime. In this paper we review the calculation for the electroweak instanton cross section using the optical theorem, including quantum effects arising from interactions in the initial state and show that this leads to an exponential suppression of the cross section at all energies, rendering the process unobservable.

arXiv comment18 pages, 7 figures

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• How to discover QCD Instantons at the LHC
• Searching for QCD Instantons at Hadron Colliders
• Hunting for QCD Instantons at the LHC in Events with Large Rapidity Gaps
• Double and multiple bangs at tau neutrino telescopes: A novel probe of sphalerons with cosmogenic neutrinos
• Spectral action and the electroweak $\theta$-terms for the Standard Model without fermion doubling