On the Consistency of the Ladder Approximation and the Rainbow Approximation of Dyson-Schwinger Equation of QCD
نویسندگان
چکیده
We study the consistency of the ladder approximation and the rainbow approximation of the Dyson-Schwinger equation of QCD. By considering the non-Abelian property of QCD, we show that the QED-type Ward-Takahashi identity is not required for the rainbow-ladder approximation of QCD. It indicates that there does not exists any internal inconsistency in the usual rainbow-ladder approximation of QCD. In addition, we propose an modified ladder approximation which guarantees the Slavnov-Taylor identity for the quark-gluon vertex omitting the ghost effect in the approximation. PACS numbers: 11.15.Tk, 12.38.Lg, 12.38.Aw ∗Corresponding Author
منابع مشابه
Nonlinear effects in Schwinger-Dyson Equation
We study nonlinear effects in the QED ladder Schwinger-Dyson(SD) equation. Without further approximations, we show that all nonlinear effects in the ladder SD equation can be included in the effective couplings and how a linear approximation works well. The analyses is generalized in the case of the improved ladder calculation with the Higashijima-Miransky approximation. The dynamical symmetry ...
متن کاملGoldstone Theorem and Diquark Confinement Beyond Rainbow-Ladder Approximation
The quark Dyson-Schwinger equation and meson Bethe-Salpeter equation are studied in a truncation scheme that extends the rainbow-ladder approximation such that, in the chiral limit, the isovector, pseudoscalar meson remains massless. Quarkquark (diquark) correlations, which are bound in rainbow-ladder approximation, are destabilised by repulsive contributions that only appear at higher order in...
متن کاملMeson Elastic and Transition Form Factors
The Dyson–Schwinger equations of QCD, truncated to ladder-rainbow level, are used to calculate meson form factors in impulse approximation. The infrared strength of the ladder-rainbow kernel is described by two parameters fitted to the chiral condensate and fπ; the ultraviolet behavior is fixed by the QCD running coupling. This obtained elastic form factors Fπ(Q) and FK(Q ) agree well with the ...
متن کاملar X iv : h ep - t h / 96 09 15 0 v 1 1 8 Se p 19 96 Vector Positronium States in QED 3
The homogeneous Bethe-Salpeter equation is solved in the quenched ladder approximation for the vector positronium states of 4-component quantum electrodynamics in 2 space and 1 time dimensions. Fermion propagator input is from a Rainbow approximation Dyson-Schwinger solution, with a broad range of fermion masses considered. This work is an extension of earlier work on the scalar spectrum of the...
متن کاملSchwinger-Dyson approach to color superconductivity in dense QCD
The problem of color superconductivity in dense QCD is reconsidered in the improved rainbow approximation to the Schwinger-Dyson equation. The effect of the unscreened magnetic modes of gluons on the value of the color condensate is studied. In particular, it is shown that, at sufficiently large values of the chemical potential, these modes lead to the enhancement of the superconducting order p...
متن کامل