Ref HAL: hal-00266461_v1
Ref Arxiv: hep-ph/0412152
DOI: 10.1016/j.physletb.2005.08.007
Ref. & Cit.: NASA ADS
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77 citations
Abstract:

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.

Ref HAL: hal-00266382_v1
Ref Arxiv: hep-ph/0412063
DOI: 10.1016/j.nuclphysbps.2005.08.045
Ref. & Cit.: NASA ADS
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19 citations
Abstract:

We rewiew and scrutinize the existing mass determinations of the pentaquarks from the exponential Laplace Sum Rules (LSR). We do not find any sum rule window for extracting optimal and reliable results from the LSR, due to the unusual slow convergence of the OPE and to the exceptional important role of the QCD continuum into the spectral function in this channel. Instead, we use in this channel,for the first time, Finite Energy Sum Rules (FESR), which exhibit a nice stability in the QCD continuum threshold t_c, at which one can extract, with a good accuracy, the mass of the lowest resonance. Including the D=7, 9 condensate contributions in the OPE, we obtain M_Theta=(1513+- 114) MeV, and the corresponding residue lambda_Theta^2= -(0.14-- 0.49)x 10^{-9} GeV^{12}, which favours the I=0, J=1/2, and negative parity S-wave interpretation of the Theta (1540). However, our analysis indicates a degeneracy between the unmixed I=0 and I=1 S-wave states. In the I=0, J=1/2, P-wave channel, we obtain, for the P-resonance, M_P = (1.99+- 0.19) GeV and lambda_P= -(0.7--7.1)x 10^{-9} GeV^{14}, which we expect to be discovered experimentally. Our results also suggest that some intuitive choices of the continuum threshold used in the LSR literature are inconsistent with the FESR results. Finally, a study of the Theta-K-N coupling using a vertex sum rule shows that, for the I=0, S-wave channel, the leading OPE contributions only start to order alpha_s^2 in the chiral limit m_s=0, indicating that the Theta is very narrow.

Comments: Contribution to the QCD 04 International Conference (Montpellier-5-9th July 2004) and to HEP-MAD 04 International Conference (Antananarivo 27th Sept-2nd Oct. 2004).

Ref Arxiv: hep-ph/0411145
DOI: 10.1016/j.nuclphysbps.2005.08.0
Ref. & Cit.: NASA ADS
Abstract:

This talk summarizes the study of the dynamics of the heavy-light \bar Qq open charm and beauty mesons obtained in [1] using QCD spectral sum rules (QSSR) and motivated by the recent experimental discovery of the D{sJ}(2317) and D{sJ}(2457) mesons. The important r\^ole of the chiral condensate <\bar\psi\psi> in the mass-splittings between the scalar-pseudoscalar mesons is emphasized. The emerging value of the running charm quark mass for reproducing the well-known D(0-) and Ds(0-) masses is: mc(mc)=1.13^{+0.08}_{-0.04} GeV, which confirms previous estimates from this channel [2]. Using this value, the sum rules give: M{Ds(0+)}= (2297+- 113) MeV, and a small SU(3) breaking: M{Ds{(0+)}}-M{D{(0+)}}= 25 MeV. Extending the analysis to the B-system, we find M{B(0+)}- M{B(0-)}= (422+- 196) MeV = M{Ds(0^+)}-M{Ds(0^-)}. Assuming an approximate (heavy and light) flavour and spin symmetries of the mass-splittings as indicated by the previous results, one also deduces M{D*s(1+)}= (2440+- 113) MeV. Finally, one also gets: f{D(0+)}= (217+- 25) MeV much bigger than f\pi=130.6 MeV, suggesting a large violation of the 1/sqrt{M_D} scaling, while the size of the SU(3) breaking ratio f{Ds(0+)}/f{D(0+)}= 0.93+- 0.02 is opposite to the one of the 0^- channel of about 1.14.

Comments: Talk presented at the 11th High-Energy Physics International Conference in Quantum Chromodynamics QCD 04 (5-9th July 2004-Montpellier-France) and partly presented at the 2nd High-Energy Physics International Conference HEP-MAD 04 (27th Sept.- 2nd Oct. 2004-Antananarivo-Madagascar).

Ref HAL: hal-00328139_v1
Ref Arxiv: hep-ph/0208271
Ref. & Cit.: NASA ADS
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Abstract:

We quantitatively study the effects, beyond the SVZ-expansion, due to instanton and tachyonic gluon mass, to the scalar isoscalar two-point functions supporting the fact that the QCD spectral sum do not favour the $\bar uu+\bar dd$ interpretation of the broad and low mass ?(0.6). Then, we emphasize that a measurement of the Ds semileptonic decays into ?? can reveal in a model-independent way its eventual gluon component ?B. The analysis also implies that one expects an observation of the $K\bar K$ final states from the ?B which may compete (if phase space allowed) with the one from a low mass $\bar ss$ state assumed in the literature to be the SU(3) partner of the observed u(0.6) if the latter is a $\bar uu+\bar dd$ state.

Comments: DOI: 10.1016/S0920-5632(03)01824-3

Ref HAL: hal-00266460_v1
Ref Arxiv: hep-ph/0307248
DOI: 10.1016/j.physletb.2004.11.002
Ref. & Cit.: NASA ADS
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90 citations
Abstract:

We study the dynamics of the the spin zero open charm and beauty mesons using QCD spectral sum rules (QSSR), where we observe the important r\^ole of the chiral condensate <\bar \psi\psi> in the mass-splittings between the scalar-pseudoscalar mesons. Fixing the sum rule parameters for reproducing the well-known D(0-) and Ds(0-) masses, we re-obtain the running charm quark mass: mc(mc)=1.13^{+0.08}_{-0.04} GeV, which confirms our recent estimate from this channel [1]. Therefore, using sum rules, with no-free parameters, we deduce M_{Ds(0+)}= (2297+- 113) MeV, which is consistent with the observed Ds(2317) meson, while a small SU(3) breaking of about 25 MeV for the Ds(0+)-D(0+) mass-difference has been obtained. We extend our analysis to the B-system and find M{B(0+)}- M{B(0-)}= (422+- 196) MeV confirming our old result from moment sum rules [2]. Assuming an approximate (heavy and light) flavour and spin symmetries of the mass-splittings as indicated by our results, we also deduce M_{D*s(1+)}= (2440+-113) MeV in agreement with the observed D{sJ}(2457). We also get: f{D(0+)}= (217+- 25) MeV much bigger than fpi=130.6 MeV, while the size of the SU(3) breaking ratio f{Ds(0+)}/f{D(0+)}= 0.93+- 0.02 is opposite to the one of the 0- channel of about 1.14.

Ref Arxiv: hep-ph/0303004
DOI: 10.1016/j.physletb.2003.06.058
Ref. & Cit.: NASA ADS
19 citations
Abstract:

We evaluate systematically some new contributions of the QCD scalar mesons, including radiative decay-productions, not considered with a better attention until now in the evaluation of the hadronic contributions to the muon anomaly. The sum of the scalar contributions to be added to the existing Standard Model predictions a_mu^{SM} are estimated in units 10^{-10} to be a^{S}_mu= 1.0(0.6) [TH based]} and 13(11) [ PDG based], where the errors are dominated by the ones from the experimental widths of these scalar mesons. PDG based results suggest that the value of a_mu^{SM} and its errors might have been underestimated in previous works. The inclusion of these new effects leads to a perfect agreement (< 1.1\sigma) of the measured value a^{exp}_mu and a_mu^{SM} from tau-decay and implies a (1.5 ~ 3.3) sigma discrepancy between a^{exp}_mu and a_mu^{SM} from e^+e^- into hadrons data. More refined unbiased estimates of a_mu^{SM} require improved measurements of the scalar meson masses and widths. The impact of our results to a_mu^{SM} is summarized in the conclusions.

Ref Arxiv: physics/0212085
Ref. & Cit.: NASA ADS
Abstract:

In the first part of this report, I discuss the sociological role of fundamental research in Developing Countries (DC) and how to realize this program. In the second part, I give a brief and elementary introduction to the field of high-energy physics (HEP), accessible to a large audience not necessary physicists. The aim of this report is to make piliticians and financial bakers aware oon the long-term usefulness of fundamental research in DC and on the possible globalisation of HEP and, in general, of science.

Comments: English version of the communications in French at the press: Tribune de Madagascar (# 4212, 26 nov.2002)