Elementary particles in the early Universe

TL;DR

This paper explores how the properties of elementary particles and their interactions in the Standard Model change at extremely high temperatures, resembling conditions in the early Universe, using gauge group contractions.

Contribution

It introduces a contraction-based approach to model the evolution of the Standard Model at high temperatures, detailing intermediate stages and exact Lagrangians.

Findings

Particles lose mass at infinite temperature

Electroweak interactions become long-range and neutral

Particles of different types do not interact at high temperature

Abstract

The high-temperature limit of Standard Model generated by the contractions of gauge groups is discussed. Contraction parameters of gauge group $SU(2)$ of Electroweak Model and gauge group $SU(3)$ of Quantum Chromodynamics are taken identical and tending to zero when temperature increase. Properties of the elementary particles change drastically at the infinite temperature limit: all particles lose masses, all quarks are monochromatic. Electroweak interactions become long-range and are mediated by the neutral currents. Particles of different kind do not interact. It looks like some stratification with only one sort of particles in each stratum. The Standard Model passes in this limit through several stages, which are distinguished by the powers of contraction parameter. For any stage the intermediate models are constructed and the exact expressions for the respective Lagrangians are presented. The developed approach describes the evolution of Standard Model in the early Universe from the Big Bang up to the end of several nanoseconds.