How to discover QCD Instantons at the LHC

Abstract

The Standard Model of particle physics predicts the existence of quantum tunnelling processes across topological inequivalent vacua, commonly known as Instantons. In Quantum Chromodynamics, these Instantons play a fundamental role in explaining much of the theory long-distance behaviour. However, they have not yet been observed experimentally. Their direct observation would mark a breakthrough in modern particle physics, shedding light on our fundamental understanding of the non perturbative dynamics in the Standard Model. Recently, new calculations for QCD Instanton processes in proton–proton collisions became public, suggesting sizeable cross sections as well as possible experimental signatures at the LHC. In this work, we explore possible analysis strategies for the LHC experiments to discover small-size QCD Instanton induced processes. Moreover, we derive a first limit on the Instanton production cross section using published data of Minimum Bias processes at $$\sqrt{s}=$$ s = 13 TeV at the LHC.

Searches for QCD instantons with forward proton tagging

“…Finally we remind that the decay of the instanton produces one additional pair of each flavour of light (m f < 1/ρ) quark [11,13,15]. So in the case of the signal, we expect to observe a larger number of strange and charm particles than in background events.…”

“…1 The problem is that the largesize instanton is very challenging to distinguish from various a e-mail: Marek.Tasevsky@cern.ch (corresponding author) b e-mail: v.a.khoze@durham.ac.uk c e-mail: daniel.l.milne@durham.ac.uk d e-mail: ryskin@thd.pnpi.spb.ru 1 The QCD instanton production in inclusive events at the LHC was considered in Refs. [11][12][13].…”

Extracting Instantons from the Lattice

“…Recent theoretical advances suggest sizeable contributions to interquark forces in mesons [3] as well promising possibilities for experimental verification. They are considered on of last predictions of the standard model needing experimental verification and here are increasing efforts to find instanton signatures at the LHC [4], [5].…”