Ref Arxiv: hep-ph/0110141
DOI: 10.1016/S0370-2693(01)01274-6
Ref. & Cit.: NASA ADS
72 citations
Abstract:

We consider an interpretation of the recent lattice data on the current-current correlators in the x-space. The data indicate rather striking difference between (axial)vector and (pseudo)scalar channels which goes beyond the predictions of the standard non-perturbative models. We argue that if the difference is to be explained by power corrections, there is a unique choice of the form of the correction. We discuss the emerging picture of the power corrections.

Ref Arxiv: hep-ph/0108242
DOI: 10.1016/S0370-2693(01)01116-9
Ref. & Cit.: NASA ADS
79 citations
Abstract:

The pseudoscalar sum rules of the heavy-light quark systems are used for extracting simultaneously the c,b quark masses and the decay constants f_D_(s),f_B_(s) of the D_(s),B_(s) mesons. To order alpha_s^2, one obtains the running quark masses: m_c(m_c)=(1.10 \pm 0.04) GeV, m_b(m_b)=(4.05\pm 0.06) GeV, the perturbative pole masses: M_c=(1.46\pm 0.04) GeV, M_b=(4.69\pm 0.06) GeV, and the decay constants: f_D=(205\pm 20) MeV, f_B=(203\pm 23) MeV and f_D_s=(235\pm 24) MeV, f_B_s=(236\pm 30) MeV, in the normalization where f_\pi= 130.56 MeV. The fitted values of the pole and running masses satisfy quite well their three-loop perturbative relation. The value f_D = f_B confirms earlier findings from the sum rule that the 1/M_P^1/2 heavy quark symmetry scaling law is affected by large 1/M_P corrections.

Ref Arxiv: hep-ph/0108065
Ref. & Cit.: NASA ADS
Abstract:

We present a new independent evaluation of the hadronic and QCD contributions to the QED running coupling \alpha(M_Z) and to the muonium hyperfine splitting \nu. We obtain: \Delta\alpha_{had}=2770(17)10^{-5} and \Delta\nu_{had}=232.5(2.5) Hz. Combined with the QED and Electroweak Standard Model contributions, they lead to: \alpha^{-1}(M_Z)=128.926(25) and to the Fermi energy splitting \nu_F=4~459~031~783(229) Hz, where for the latter, we have used, in addition, the precise measurement of the muonium hyperfine splitting \nu_{exp}. We use \nu_F in order to predict the ratios of masses m_{\mu}/m_e=206.768~276(11) and of the magnetic moments \mu_{\mu}/\mu^e_B=4.841~970~47(25)10^{-3}, which are in excellent agreement with the ones quoted by the Particle Data Group. These remarkable agreements can provide strong constraints on some contributions beyond the Standard Model.

Ref Arxiv: hep-ph/0205092
DOI: 10.1016/S0370-2693(02)02133-0
Ref. & Cit.: NASA ADS
16 citations
Abstract:

We present the first QCD spectral sum rules analysis of the SU(3) breaking parameter \xi and an improved estimate of the renormalization group invariant (RGI) bag constant \hat{B}_{B_q} both entering into the B^0_{d,s} - \bar{B}^0_{d,s} mass-differences. The averages of the results from the Laplace and moment sum rules to order \alpha_s are f_B\sqrt{\hat B_B} \simeq (247 \pm 59) MeV and \xi \equiv f_{B_s} \sqrt{\hat B_{B_s}} / f_{B} \sqrt{\hat B_{B}} \simeq (1.18\pm 0.03), in units where f_\pi=130.7 MeV. Combined with the experimental data on the mass-differences \Delta M_{d,s}, one obtains the constraint on the CKM weak mixing angle |V_{ts}/V_{td}|^2 > 20.0 (1.1). Alternatively, using the weak mixing angle from the analysis of the unitarity triangle and the data on \Delta M_d, one predicts \Delta M_s=18.6 (2.2) ps^{-1} in agreement with the present experimental lower bound and within the reach of Tevatron 2.

Ref Arxiv: hep-ph/0103199
DOI: 10.1016/S0370-2693(01)00743-2
Ref. & Cit.: NASA ADS
90 citations
Abstract:

We present a new independent evaluation of the hadronic vacuum polarization contributions a_l{had}(l.o)=(1/2)(g-2)_l{had}(l.o) to the anomalous magnetic moment (anomaly) of the muon and tau leptons using tau-decays and e+e- data. The alone theoretical input used for describing the high-energy region not accessible experimentally is perturbative QCD plus (negligible) additional effects due to the QCD vacuum condensates. We obtain: a_mu{had}(l.o)= 7020.6(75.6)10^{-11} and a_tau{had}(l.o)= 353.6(3.8)10^{-8}, which we compare with previous determinations. Our analysis leads to the Standard Model (SM) prediction: a_mu^{SM}=116~591~846.9(78.9)10^{-11}.Confronting a_mu^{SM} with the recent BNL measurement leads to a_mu{new}= a_mu{exp}-a_mu{SM}=176(170)10^{-11}. Combined with the mean existing determinations of a_mu^{had}(l.o), this leads to the conservative range: -42 < a_mu{new}10^{11} < 413 at 90% CL, from which we derive conservative lower bounds on the scales of some new physics. We also update our old predictions of the SM contributions to a_tau. Including QED to sixth order, higher order hadronic and electroweak contributions, we obtain a_tau{SM}=117 755(7)10^{-8}, waiting for a future precise measurement of a_tau.

Comments: Referred to by:Erratum to: “Muon and tau anomalies updated”: [Phys. Lett. B 513 (2001) 53], Physics Letters B, Volume 526, Issues 3-4, 7 February 2002, Pages 414-415

Ref Arxiv: hep-ph/0012235
DOI: 10.1016/S0920-5632(01)01137-9
Ref. & Cit.: NASA ADS
35 citations
Abstract:

We review the analysis of the quark and gluon substructures of the scalar mesons from QCD spectral sum rules and some low-energy theorems applied to the scalar QCD anomaly current. The present data favour equal components of \bar uu+ \bar dd and of gg in the wave functions of the low-mass (below 1 GeV) scalar mesons, which make the wide \sigma and the narrow f_0(980) as \eta'-like particles, which can have strong couplings to meson pairs through OZI violations. A coherent picture of the other I=0 scalar mesons spectra within this mixing scheme is shortly discussed. We also expect the a_0(980) to be the lowest isovector \bar ud state, and the K^*_0(1430) its \bar ds partner.

Comments: Two-column latex files, 8 pages

Ref Arxiv: hep-ph/0012019
DOI: 10.1016/S0920-5632(01)01154-9
Ref. & Cit.: NASA ADS
11 citations
Abstract:

Recent ALEPH/OPAL data on the V-A spectral functions from hadronic tau decays are used for fixing the QCD continuum threshold at which the first and second Weinberg sum rules should be satisfied in the chiral limit, and for predicting the values of the low-energy constants f_\pi,~m_{\pi^+}-m_{\pi^0} and {L}_{10}. Some DMO-like sum rules and the $\tau$-total hadronic widths R_{\tau,V-A} are also used for extracting the values of the D=6,~8 QCD vacuum condensates and the corresponding (in the chiral limit) electroweak kaon penguin matrix elements Q^{3/2}_{8,7}\ra_{2\pi},, where a deviation from the vacuum saturation estimate has been obtained. Combining these results with the one of the QCD penguin matrix element Q^{1/2}_{6}\ra_{2\pi} obtained from a (maximal) \bar qq-gluonium mixing scheme from the scalar meson sum rules, we deduce, in the Electroweak Standard Model (ESM), the conservative upper bound for the CP-violating ratio: \epsilon'/\epsilon \leq (22\pm 9) 10^{-4}, in agreement with the present measurements.

Comments: This is a summary of the paper “New QCD Estimate of the Kaon Penguin Matrix Elements” hep-ph/0004247 (Nucl. Phys. B in press).