Ref HAL: hal-00861612_v1
Ref Arxiv: 1309.3177
DOI: 10.1103/PhysRevD.88.113003
Ref. & Cit.: NASA ADS
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4 citations
Commentaires: 24 pages, 22 figures

Ref HAL: hal-00803544_v1
Ref Arxiv: 1303.5284
DOI: 10.1007/JHEP07(2013)146
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2 citations
Commentaires: 24 pages, 10 figures

Ref Arxiv: 1209.2023
Ref. & Cit.: NASA ADS
Résumé:

Using recent values of the QCD (non-) perturbative parameters given in Table 1 and an estimate of the N3LO QCD perturbative contributions based on the geometric growth of the PT series, we re-use QCD spectral sum rules (QSSR) known to N2LO PT series and including all dimension-six NP condensate contributions in the full QCD theory, for improving the existing estimates of {m}_{c,b} and f_{D_(s)}, f_{B_(s)} from the open charm and beauty systems. We especially study the effects of the subtraction point on "different QSSR data" and use (for the first time) the Renormalization Group Invariant (RGI) scale independent quark masses in the analysis. The estimates [rigourous model-independent upper bounds] reported in Table 8: f_D/f_\pi=1.56(5)[< 1.68(1)], f_B/f_\pi=1.58(5)[< 1.80(3)] and f_{D_s}/f_K= 1.58(4) [< 1.63(1)], f_{B_s}/f_K=1.50(3)[< 1.61(3.5)], which improve previous QSSR estimates, are in perfect agreement (in values and precisions) with some of the experimental data on f_{D,D_s} and on recent lattice simulations within dynamical quarks. These remarkable agreements confirm both the success of the QSSR semi-approximate approach based on the OPE in terms of the quark and gluon condensates and of the Minimal Duality Ansatz (MDA) for parametrizing the hadronic spectral function which we have tested from the complete data of the J/\psi and \Upsilon systems. The values of the running quark masses m_c(m_c)=1286(66) MeV and m_b(m_b)= 4236(69) MeV from M_{D,B} are in good agreement though less accurate than the ones from recent J/\psi and \Upsilon sum rules.

Commentaires: 13 pages, 20 figures, 8 tables: partly presented at the 16th QCD international conference (QCD 12), Montpellier, 2-6th july 2012

Ref HAL: hal-00777563_v1
Ref Arxiv: 1207.2476
DOI: 10.1088/1475-7516/2012/11/021
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18 citations
Commentaires: 32 pages. V2: changes to match the version accepted for publication in JCAP Journal: JCAP 11 (2012) 021

Ref Arxiv: 1205.4547
Ref. & Cit.: NASA ADS
Résumé:

According to supersimplicity in MSSM, a renormalization scheme (SRS) may be defined for any high energy 2-to-2 process, to the 1loop EW order; where the helicity conserving (HC) amplitudes, are expressed as a linear combination of just three universal logarithm-involving forms. All other helicity amplitudes vanish asymptotically. Including to these SRS amplitudes the corresponding counter terms, the "supersimple" expressions for the high energy HC amplitudes, renormalized on-shell, are obtained. Previously, this property was noted for a large number of processes that do not involve Yukawa interactions or renormalization group corrections. Here we extend it to $e^-e^+\to t \bar t$, which does involve large Yukawa and renormalization group contributions. We show that the resulting "supersimple" expressions may provide an accurate description, even at energies comparable to the SUSY scale. Such descriptions clearly identify the origin of the important SUSY effects, and they may be used for quickly constraining physics contributions, beyond MSSM.

Commentaires: 26 pages, 15 figures

Ref Arxiv: 1204.1236
Ref. & Cit.: NASA ADS
Résumé:

We estimate the masses of the 1-- and 0++ heavy four-quark and molecule states by combining exponential Laplace (LSR) and finite energy (FESR) sum rules known perturbatively to lowest order (LO) in \alpha_s but including non-perturbative terms up to the complete dimension-six condensate contributions. This approach allows to fix unambiguously and more precisely the value of the QCD continuum threshold (often taken ad hoc) at which the optimal result is extracted. We use double ratio of sum rules (DRSR) for determining the SU(3) breakings terms. We also study the effects of the heavy quark mass definitions on these LO results. The SU(3) mass-splittings of about (70 -- 110) MeV and the ones of about (250-300) MeV between the lowest ground states and their 1st radial excitations are (almost) heavy-flavour independent. The mass predictions summarized in Table 4 are compared with the ones in the literature (when available) and with the three Y_c(4260, 4360, 4660) and \Y_b(10890) 1-- experimental candidates. We conclude (to this order approximation) that the lowest observed state cannot be a pure four-quark nor a pure molecule but may result from their mixings. Our predictions can be further tested at LHC_b and in some other hadron factories.

Commentaires: 11 pages, 11 figures, 4 tables

Ref HAL: hal-00777643_v1
Ref Arxiv: 1205.1004
DOI: 10.1016/j.crhy.2012.05.001
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29 citations
Commentaires: Invited review submitted to Comptes Rendus de l'Academie des Sciences, special issue on "Dark matter and dark energy" (Eds. C. Boehm and P. Brax). 82 pages. V2: matches the published version Journal: Comptes Rendus Physique, Volume 13, Issue 6, p. 740-782 (2012)