Dynamical Masses and Gauge invariance: beyond the perturbative approach.

• Grant number: 23/03722-9
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: August 01, 2023
• Status: Discontinued
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Principal Investigator: Nathan Jacob Berkovits
• Grantee: Duive Maria Van Egmond
• Host Institution: Instituto de Física Teórica (IFT). Universidade Estadual Paulista (UNESP). Campus de São Paulo. São Paulo , SP, Brazil
• Associated research grant: 21/14335-0 - ICTP South American Institute for Fundamental Research: a regional center for Theoretical Physics, AP.ESP
• Associated scholarship(s): 24/10642-4 - Spectral properties and massive fields in non-perturbative QCD, BE.EP.PD

Abstract

Non-abelian Yang-Mills gauge theories describing the electroweak and strong interaction, cornerstones of the Standard Model,are far from completely understood. Perturbative Quantum Chromodynamics describes the high-energy region of the strong interaction successfully, but until today no coherent analytical description of the low-energy region exists. (Gauge-fixed) lattice results indicate massive behaviour of the gluon propagator in the low-energy regime. In the electroweak sector, spontaneous symmetry breaking of a "global gauge symmetry" is the only known way to provide masses for elementary vector bosons, but this is theoretically inconsistent and, even more disturbing, leads to explicit gauge dependence of the elementary Källén-Lehmann spectral functions. We construct analytical frameworks for gauge-invariant mass generation in Yang-Mills theories. Therefore we use local gauge-invariant composite operators in the Fröhlich-Morchio-Strocchi framework to not only access the electroweak spectrum but also the phase structure in an explicitlygauge-invariant fashion. We will obtain gauge-invariant results predicting the results of Standard Model electroweak theory, as well as extend the description of massive gauge bosons to Minkowski spacetime. We test the Nielsen identities that guarantee gauge parameter independence (but not gauge invariance) of physical observables. We also study the deconfinement transition for pure Yang-Mills models at finite temperature with a dynamically generated mass while preserving the gauge symmetry.