Jl. Kneur et D. Reynaud, Toward convergence of the variational mass expansion and Chiral Symmetry Breaking parameters, NUCL PH B-P, 96, 2001, pp. 255-258
We re-examine a modification of perturbative expansions, valid for asymptot
ically free theories, producing "variationally improved" expansions of phys
ical quantities relevant to dynamical (chiral) symmetry breaking. The large
order behaviour of this expansion is drastically improved, with respect to
the original perturbative expansion (making the series at least Borel summ
able, in a certain range of renormalization scheme parameters). We argue th
at non-perturbative estimates of the order parameters of QCD chiral symmetr
y breaking are therefore possible in this framework.