Tribute to Francisco (Paco) Yndurain

This part of the talk aims to present briefly the biodata and the exceptional career of Paco Yndurain who left us suddenly in June 2008. The scientific part: Light Scalar Mesons in QCD is published in the proceedings of QCD 08 (Montpellier 7-12th july 2008: arXiv:0811.0563 [hep-ph]).Comment: 7 pages, Invited Plenary Talk given at Confinement8, 1-6 sept., Mainz (DE) (bug corrected

Revisiting f_B and m_b(m_b) from HQET spectral sum rules

Using recent values of the QCD (non-) perturbative parameters given in Table 1, we reconsider the extraction of f_B and the on-shell mass M_b from HQET Laplace spectral sum rules known to N2LO PT series and including dimension 7 condensates in the OPE. We especially study the convergence of the PT series, the effects on "different spectral sum rules data" of the continuum threshold and subtraction point varied in a larger range than in the existing literature and include in the error an estimate of the N3LO PT series based on a geometric growth of the PT series. We obtain the Renormalization Group Invariant (RGI) universal coupling : \hat f_B^\infty=0.416(60) GeV^{3/2} in the static limit M_b \to \infty and the physical decay constant including 1/M_b corrections: f_B^{hqet}=199(29) MeV. Using the ratio of sum rules, we obtain, to order \alpha_s^2, the running mass m_b(m_b)=4213(59) MeV. The previous results are in good agreement with the ones from QCD spectral sum rules (QSSR) in full QCD to the same order from the same channel [1]: f_B^{qcd}=206(7) MeV and m_b(m_b)^{qcd}=4236(69) MeV.Comment: 8 pages, 9 figures, 5 tables. Extended and Revised version which matches with the published one in PL

V-A hadronic tau decays : a laboratory for the QCD vacuum

ALEPH/OPAL data on the V-A spectral functions from hadronic tau decays are used in connection with a set of Laplace transform sum rules (LSR) for fixing the size of the QCD vacuum condensates up to dimension 18. Our results favour the ones from large-N_c QCD within the Minimal Hadronic Approximation (MHA) and show a violation of about a factor 2-5 of the vacuum saturation estimate of the dimension-six to -ten condensates. We scrutinize the different determinations of the QCD vacuum condensates using tau-decays data. After revisiting some of the existing results, we present coherent values of the condensates from different methods.Comment: Version to appear in Phys. Lett.

Mini-review on QCD spectral sum rules

Taking the example of the most popular and well-established Borel / Laplace / Exponential sum rule (LSR), I shortly review some of its recent applications in hadron physics namely the estimates of non-perturbative condensates, the determination of the light and heavy quark masses, the extraction of the heavy-light decay constants, the estimates of charmonium and bottomium molecule masses and the properties of scalar gluonium. In addition to the standard \tau (sum rule variable) and t_c (QCD continuum threshold) stablity criteria, I introduce a new stability criterion versus the arbitrary QCD subtraction point \mu for extracting the optimal results when radiative QCD corrections are included. Future improvements on further uses of QCD spectral sum rules (QSSR) are commented.Comment: 6 pages, 8 figures, 3 tables, Mini-review talk given at the 17th International Conference on Quantum Chromodynamics (QCD 14) (29 june - 3 july 2014, Montpellier-France), to appear in Nucl. Phys. B (Proc. Suppl.). Some typos corrected. References update

Decay Constants of Heavy-Light Mesons from QCD

We summarize recently improved results for the pseudoscalar [1,2] and vector [3] meson decay constants and their ratios from QCD spectral sum rules where N2LO + estimate of the N3LO PT and power corrections up to d< 6 dimensions have been included in the SVZ expansion. The "optimal results" based on stability criteria with respect to the variations of the Laplace/Moments sum rule variables, QCD continuum threshold and subtraction constant \mu are compared with recent sum rules and lattice calculations. To understand the "apparent tension" between some recent results for f_B*/f_B, we present in Section 8 "a novel extraction" of this ratio from heavy quark effective theory (HQET) sum rules by including the normalization factor (M_b/M_B)^2 relating the pseudoscalar to the universal HQET correlators for finite b-quark and B-meson masses. We obtain f_B*/f_B=1.025(16) in good agreement with the one 1.016(16) from (pseudo)scalar sum rules in full QCD [3]. We complete the paper by including new improved estimates of the scalar, axial-vector and B^*_c meson decays constants (Sections 11-13). For further phenomenological uses, we attempt to extract a Global Average of different sum rules and lattice determinations of the decay constants which are summarized in Tables 2-6. We do not found any deviation of these SM results from the present data.Comment: New results on scalar, axial and B*c meson decay constants added in Sections 11-13. 11 pages. 14 new figures, 2 new tables. Contents of the tables and of the text improved. References added and updated. Misprints corrected. arXiv admin note: substantial text overlap with arXiv:1404.664