Effects of divergent ghost loops in the presence of dynamical quarks

• Grant number: 14/16247-8
• Support type: Scholarships in Brazil - Master
• Effective date (Start): October 01, 2014
• Effective date (End): July 31, 2016
• Field of knowledge: Physical Sciences and Mathematics - Physics - Elementary Particle Physics and Fields
• Cooperation agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal researcher: Arlene Cristina Aguilar
• Grantee: Clara Teixeira Figueiredo
• Home Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

In this project we will analyse certain characteristic features encoded in some of the fundamental QCD Green's functions. Basically, we want to track what are the consequences generated in the infrared behavior of the gluon propagator and the three-gluon vertex, due to the fact that the ghost fields remain massless in the non-perturbative QCD regime. Recently, studies for a pure Yang-Mills theory (no quarks fields) have showed that the ghost loops that contribute to the aforementioned Green's functions, display a similar type of infrared divergence encountered in a purely perturbative treatment. On the other hand, the perturbative divergences, generated by the gluonic loops, are tamed by the dynamical generation of an effective gluon mass, which takes place in the non-perturbative regime of the theory. In four dimensions, those divergences are logarithmic, thus causinga mild impact on the infrared behavior of the Green's functions. In the case of d = 3 the divergence has a linear nature, which implies in a significant enhancement in their effects. In the case of gluon propagator, these effects do not interfere with its finiteness, but make its first derivative diverge at the origin. Moreover, we also notice the appearance of a maximum in its low momenta region. The behavior of the three-gluon vertex is also affected, leading to a divergent behavior which it is clearly seen in aspecial kinematic configuration, usually employed in the lattice simulations. Using the Schwinger-Dyson equations, we will study whether the aforementioned effects persist or not and how they are modified when the quark fields are included in the theory. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

AGUILAR, A. C.; BINOSI, D.; FIGUEIREDO, C. T.; PAPAVASSILIOU, J. Unified description of seagull cancellations and infrared finiteness of gluon propagators. Physical Review D, v. 94, n. 4 AUG 3 2016. Web of Science Citations: 8.