相关论文: Non-perturbative Expansion, Renormalons, and $\tau…
In the context of the inclusive $\tau$-decay, we analyze various forms of perturbative expansions which have appeared as modifications of the original perturbative series. We argue that analytic perturbation theory, which combines…
A non-perturbative expansion method which gives a well-defined analytic continuation of the running coupling constant from the spacelike to the timelike region is applied to the inclusive semileptonic decay of the $\tau$--lepton. The method…
We show that renormalization group improvement, making use of analyticity and the structure of the operator product expansion, combined with a non-perturbative expansion method allows one to describe quarkonium states via QCD sum rules…
We apply an analytic description to the inclusive decay of the $\tau$ lepton. We argue that this method gives not only a self-consistent description of the process both in the timelike region by using the initial expression for $R_\tau$ and…
We apply analytic perturbation theory to the inclusive decay of a $\tau$ lepton into hadrons. It is shown that the resulting analyticity of the coupling constant strongly influences the value of the QCD $\Lambda$-parameter extracted from…
The calculation of perturbative corrections to the spectral moments observable in hadronic $\tau$ decays is reconsidered. The exact order-$\alpha_s^3$ results and the resummation procedure of Le~Diberder and Pich are compared with a partial…
The structure of the QFT expansion is studied in the framework of a new "Invariant analytic" version of the perturbative QCD. Here, an invariant (running) coupling $a(Q^2/\Lambda^2)=\beta_1\alpha_s(Q^2)/4\pi$ is transformed into a…
We apply the operator product expansion to resum the leading nonperturbative corrections to the endpoint region of the lepton spectrum in inclusive semileptonic $B\to X_q\,\ell\,\bar\nu$ decays, taking into account a finite quark mass $m_q$…
A novel, non-power, expansion of QCD quantities replacing the standard perturbative expansion in powers of the renormalized couplant a has recently been introduced and examined by two of us. Being obtained by analytic continuation in the…
We discuss the renormalon-based approach to power corrections in non-singlet deep inelastic scattering structure functions and compare it with the general operator product expansion. The renormalon technique and its variations relate the…
We argue that accounting for higher order corrections in QCD by integrating a running coupling constant through an infrared region can be most easily done with making use of a scheme without the Landau pole. Within this approach the entire…
Sufficiently inclusive observables in the decay of the tau lepton can be calculated using the methods of perturbative QCD. These include the asymmetry parameter $A_\tau$ that determines that angular distribution of the total hadron momentum…
Precise theoretical predictions are a key ingredient for an accurate determination of the structure of the Langrangian of particle physics, including its free parameters, which summarizes our understanding of the fundamental interactions…
A technique to sum up the regular corrections appearing under the analytic continuation from the spacelike momentum region to the timelike one is proposed. A perturbative part of the inclusive semileptonic decay width of the tau-lepton in…
A technique called analytic perturbation theory, which respects the required analytic properties, consistent with causality, is applied to the definition of the running coupling in the timelike region, to the description of inclusive…
We describe some ways how higher order corrections can reveal themselves if integrated over the infrared region. We show that in different renormalization group (RG) schemes and for some observables one has no factorial divergences. We…
The semihadronic tau decay width allows a clean extraction of the strong coupling constant at low energies. We present a modification of the standard "contour improved" method based on a derivative expansion of the Adler function. The…
The infrared behavior of the Adler function is examined by making use of a recently derived integral representation for the latter. The obtained result for the Adler function agrees with its experimental prediction in the entire energy…
Starting from the divergent character of the perturbative expansions in QCD and using the technique of series acceleration by the conformal mappings of the Borel plane, I define a novel, non-power perturbative expansion for the Adler…
We apply analytic perturbation theory in next-to-next-to-leading order to inclusive semileptonic $\tau$-decay and study the renormalization scheme dependence. We argue that the renormalization scheme ambiguity is considerably reduced in the…