Topology and Gauge Invariance of Infrared QCD - Correlation functions and observables

• Grant number: 25/15966-5
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: January 01, 2026
• End date: February 29, 2028
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Principal Investigator: Gastão Inácio Krein
• Grantee: Bruno Rodrigues Soares
• 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

Abstract

Over several decades, Euclidean lattice simulations of quantum chromodynamics (QCD), the fundamental theory of the strong interaction, have revealed the essential role of topological field configurations known as center vortices in explaining infrared phenomena such as confinement, dynamical chiral symmetry breaking, and the high-temperature deconfinement transition. Lattice results also indicated that the gluon propagator remains finite at zero momentum, signaling dynamical mass generation. Motivated by these numerical results, we will study the interplay between massive infrared gluonic behavior and center vortex configurations, focusing on their combined impact on gauge-invariant quark and gluon correlation functions, using functional methods in the continuum. Within the Hamiltonian formulation of QCD, we will construct phenomenological vacuum wave functionals that incorporate center vortices, extend them to include quark degrees of freedom, and compute gauge-invariant quark and gluon correlation functions relevant for parton distribution and fragmentation functions. By unifying these topological and dynamical mechanisms in a single analytical framework, the research will advance our understanding of quark and gluon mass generation while strengthening the theoretical bridge between lattice simulations and continuum approaches. (AU)