2024-03-28T19:02:55Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/199582016-03-04T12:49:46Zcom_10261_61com_10261_4col_10261_314
Nonperturbative comparison of QCD effective charges
Aguilar, Arlene Cristina
Binosi, D.
Papavassiliou, Joannis
Rodriguez-Quintero, J.
Revert field
We study the nonperturbative behavior of two versions of the QCD effective charge, one obtained from the pinch technique gluon self-energy, and one from the ghost-gluon vertex. Despite their distinct theoretical origin, due to a fundamental identity relating various ingredients appearing in their respective definitions, the two effective charges are almost identical in the entire range of physical momenta, and coincide exactly in the deep infrared, where they freeze at a common finite value. Specifically, the dressing function of the ghost propagator is related to the two form factors in the Lorentz decomposition of a certain Green's function, appearing in a variety of field-theoretic contexts. The central identity, which is valid only in the Landau gauge, is derived from the Schwinger-Dyson equations governing the dynamics of the aforementioned quantities. The renormalization procedure that preserves the validity of the identity is carried out, and various relevant kinematic limits and physically motivated approximations are studied in detail. A crucial ingredient in this analysis is the infrared finiteness of the gluon propagator, which is inextricably connected with the aforementioned freezing of the effective charges. Some important issues related to the consistent definition of the effective charge in the presence of such a gluon propagator are resolved. We finally present a detailed numerical study of a special set of Schwinger-Dyson equations, whose solutions determine the nonperturbative dynamics of the quantities composing the two effective charges.
The research of J. P. is supported by the European
FEDER and Spanish MICINN under Grant
No. FPA2008-02878, and the Fundación General of the UV. The work of J. R-Q. is supported by the Spanish MEC
Grant No. FPA-2006-13825.
Peer reviewed
2009-10-15
artÃculo
http://purl.org/coar/resource_type/c_6501
Physical Review - Section D - Particles and Fields 80 (8): 085018 (2009)
1550-7998
10261/19958
10.1103/PhysRevD.80.085018
en
http://dx.doi.org/10.1103/PhysRevD.80.085018
open
American Physical Society