相关论文: V-A hadronic tau decays : a QCD laboratory
We use the procedure of pinched-weight Finite Energy Sum Rules (pFESR) to determine the OPE coefficients a_6, ...,a_16 of the flavor ud V-A correlator in terms of existing hadronic tau decay data. We show by appropriate weight choices that…
We discuss a preliminary study of the impact of duality violations on extractions from tau decay data of the D=6 VEVs which determine chiral limit Standard Model K-->pi pi matrix elements of the electroweak penguin operators.
The modern status of basic low energy QCD parameters is reviewed. It is demonstrated, that the recent data allows one to determine the light quark mass ratios with an accuracy 10-15%. The general analysis of vacuum condensates in QCD is…
A variant of QCD with the coupling suppressed in the infrared (IR) regime, as suggested by large-volume lattice calculations of the Landau-gauge gluon and ghost dressing functions, is considered. The coupling is further restricted by the…
The vector and axial-vector ALEPH hadronic spectral functions from $\tau$-decay are used to probe potential quark-hadron duality violations (DV). This is done in the framework of finite energy QCD sum rules (FESR). A pinched integration…
Hadronic $\tau$ decays provide a clean laboratory for the precise study of quantum chromodynamics (QCD). Observables based on the spectral functions of hadronic $\tau$ decays can be related to QCD quark-level calculations to determine…
Recent experimental data on tau decays are used to reconstruct the difference in hadronic spectral densities with vector and axial-vector quantum numbers. The saturation of Das-Mathur-Okubo and Weinberg sum rules is studied. Two methods of…
We use results of fits to the OPAL spectral data, obtained from non-strange hadronic \tau decays, to evaluate the difference between the vector and axial current correlators, \Pi_{V-A}(Q^2). The behavior of \Pi_{V-A}(Q^2) near euclidean…
We study extractions of |V_us| based on finite energy sum rule (FESR) analyses of hadronic tau decay data. We show (i) that the ``(0,0) spectral weight'' implementation (proposed previously in the literature as a favorable version of this…
Sum rule tests are performed on the spectral data for (i) flavor 'ud' vector- current-induced hadronic tau decays and (ii) e^+ e^- hadroproduction, in the region below s~3-4 GeV^2, where discrepancies exist between the isospin-…
We analyze how the recent precise hadronic tau-decay data on the V-A spectral function and general properties of QCD such as analyticity, the operator product expansion and chiral perturbation theory (ChPT), can be used to improve the…
We perform a finite energy sum rule analysis of the flavor ud two-point V-A current correlator, Delta Pi (Q^2). The analysis, which is performed using both the ALEPH and OPAL databases for the V-A spectral function, Delta rho, allows us to…
Using the updated ALEPH V-A spectral function from tau decays, we determine the lowest spectral moments of the left-right correlator and extract dynamical information on order parameters of the QCD chiral symmetry breaking. Uncertainties…
We analyze the lowest spectral moments of the left-right two-point correlation function, using all known short-distance constraints and the recently updated ALEPH V-A spectral function from tau decays. This information is used to determine…
A sum rule analysis of the hadronic tau-decay data can be used to determine the low-energy constants L10(mu) and C87(mu). These constants are QCD chiral-order parameters, which appear at order p^4 and p^6, respectively, in the chiral…
We re-examine the estimate of $\als$ and of the QCD condensates from $e^+e^-\rar I=1$ hadrons data. We conclude that $e^+e^-$ at low energies gives a value of $\Lambda$ compatible with the one from LEP and from tau inclusive decay. Using a…
The finite energy sum rule extraction of the strong coupling {\alpha}_s from hadronic {\tau} decay data provides one of its most precise experimental determinations. As precision improves, small non-perturbative effects become increasingly…
I extract the strange-quark mass using a $\tau$-like decay sum rule for the $\phi$-meson, and some other sum rules involving its difference with the vector component of the hadronic $\tau$-decay. As a conservative estimate, one obtains to…
Utilizing in-medium vector spectral functions which describe dilepton data in ultra-relativistic heavy-ion collisions, we conduct a comprehensive evaluation of QCD and Weinberg sum rules at finite temperature. The starting point is our…
We re-examine recent determinations of power corrections from tau-decay and confront the results with the existing ones from QCD spectral sum rules (QSSR). We conclude that contrary to the QSSR analysis, which lead to <alpha_s…