Thesis

Lattice Study of Fundamental QCD Gluon Vertices

• Call:

  IDPASC Portugal - PHD Programme 2019

• Academic Year:

  2019 / 2020

• Domain:

  Theoretical Particle Physics

• Supervisor:

  Paulo Silva

• Co-Supervisor:

  Orlando Oliveira

• Institution:

  Universidade de Coimbra

• Host Institution:

  Universidade de Coimbra

• Abstract:

  Quantum Chromodynamics (QCD) describes the interactions between quarks and gluons. At high energies the standard approach to solve QCD relies on perturbation theory. On the other hand, for small momenta where non-perturbative effects lead to the formation of bound states such as protons, neutrons, to solve QCD is a highly non-trivial task that requires different approaches. To handle the non-perturbative regime of the color interaction it is used either its formulation on a space-time lattice (lattice QCD) or rely on an infinite tower of Green’s functions, that need to be truncated to be solved, as the Dyson-Schwinger equations (DSE). Recent studies show that higher order Green functions do play a major role on the non-perturbative solution of QCD. Indeed, the simultaneous solutions of the quark gap equation together with the corresponding (approximate) equation for the three gluon Green function clearly improve our understanding of the color dynamics in the sense that the solution of the quark DSE and the quark-gluon vertex become closer to the available lattice results. Furthermore, the description of the three and possible higher order gluon Green functions encode clear information on the non-perturbative nature of the color interaction as, for example, the ghost dominance at small energy scales. Recall that the knowledge of the QCD Green functions solves completely the theory. The aim of this project is to perform higher precision studies of higher order gluon Green functions using lattice QCD simulations. This requires the generation of large statistical ensembles of gauge configurations and the development of techniques to resolve the lattice artefacts on the description of the various Green functions. The goal is also to identify and quantify those properties that are connected with the infrared dynamics of the color interaction and, hopefully, provide input to improve the continuum approach to QCD. The simulations will be performed using the supercomputer facilities at the University of Coimbra. The candidate will join a team with a large experience in lattice QCD simulations.