  Using ratios of the inverse Laplace transform sum rules within stability
criteria for the subtraction point \mu in addition to the ones of the usual tau
spectral sum rule variable and continuum threshold t_c, we extract the
\pi(1300) and K(1460) decay constants to order \alpha_s^4 of perturbative QCD
by including power corrections up to dimension-six condensates, tachyonic gluon
mass, instanton and finite width corrections. Using these inputs with enlarged
generous errors, we extract, in a model-independent and conservative ways, the
sum of the scale-independent renormalization group invariant (RGI) quark masses
(m_u+ m_q):q\equiv d,s and the corresponding running masses (m_u+m_q) evaluated
at 2 GeV. By giving the value of the ratio m_u/m_d, we deduce the running quark
masses m_{u,d,s} and condensate <\bar uu> and the scale-independent mass ratios
: 2m_s/(m_u+m_d) and m_s/m_d. Using the positivity of the QCD continuum
contribution to the spectral function, we also deduce, from the inverse Laplace
transform sum rules, for the first time to order \alpha_s^4, new lower bounds
on the RGI masses which are translated into the running masses at 2 GeV and
into upper bounds on the running quark condensate <\bar uu>. Our results
summarized in Table 2 and compared with our previous results and with recent
lattice averages suggest that precise phenomenological determinations of the
sum of light quark masses require improved experimental measurements of the
\pi(1.3) and K(1.46) hadronic widths and/or decay constants which are the
dominant sources of errors in the analysis.
