On the phenomenology of sphaleron-induced processes at the LHC and beyond

TL;DR

This paper explores the potential for detecting sphaleron-induced baryon and lepton number violation at current and future colliders, developing a new event generator and analyzing collider sensitivities across multiple energy scales.

Contribution

It introduces a modern event generator within Herwig for sphaleron processes and provides a detailed phenomenological analysis for LHC, HE-LHC, and FCC-hh.

Findings

Colliders can provide meaningful insights into sphaleron processes.

Constraints on sphaleron process rates are derived for different collider energies.

Sphaleron-induced processes could be observable at future high-energy colliders.

Abstract

We investigate the phenomenological aspects of non-perturbative baryon- and lepton-number-violating processes at hadron colliders. Such processes, induced by instanton/sphaleron configurations of the electroweak gauge fields, are believed to play a crucial role in the generation of baryon asymmetry in the early Universe at finite temperature. On the other hand, at colliders (that represent the zero-temperature high-energy regime) the rate and observability of such processes are still under debate. Motivated by current theoretical considerations, we construct a modern event generator within the general-purpose Herwig Monte Carlo framework, that aims to capture the most relevant features of the dominant processes. We perform a detailed phenomenological analysis focussing on the Large Hadron Collider, at 13 TeV proton-proton centre-of-mass energy, a potential high-energy upgrade at 27 TeV and the proposed Future Circular Collider (FCC-hh) at 100 TeV. We derive constraints on the expected rates for various parametrisations of our model. We find that all three colliders are capable of providing meaningful information on the nature of instanton/sphaleron-induced processes at various energy scales.