相关论文: Parton model sum rules
We present a new QCD sum rule with high sensitivity to the continuum regions of charm and bottom quark pair production. Combining this sum rule with existing ones yields very stable results for the msbar quark masses, m_c(m_c)$ and m_b…
Perturbative QCD has made significant progress over the last few decades. In the first part, we present an introductory overview of perturbative QCD as seen from a modern viewpoint. We explain the relation between purely perturbative…
We examine the present status of the Bjorken sum rule in the light of recent data on the spin structure functions of the proton, neutron and deuteron obtained by the CERN and SLAC experimental groups. We also discuss the role of possible…
I present a highly efficient method for evolving parton distributions in perturbative QCD. The method allows evolving the parton distribution functions according to any of the commonly-used truncations of the evolution equations (which…
We calculate the coupling constants between the light vector mesons and heavy baryons within the framework of the light-cone QCD sum rule in the leading order of heavy quark effective theory. Most resulting sum rules are stable with the…
Applications of the principle of reduction of couplings to the standard model and supersymmetric grand unified theories are reviewed. Phenomenological applications of renormalization group invariant sum rules for soft supersymmetry-breaking…
A recently proposed scheme is used to saturate the spectral side of the QCD sum rules derived from the thermal, two-point correlation functions of the vector and the axial-vector currents. At low temperature, it constructs the spectral…
The QCD sum rules for spin-dependent nucleon-nucleon interactions are formulated and their physical implications are studied. The basic object of the study is the correlation function of the nucleon interpolating field, where the matrix…
This paper presents a summary of the current status of determinations of the strong coupling constant alpha_s. A detailed description of the definition, scale dependence and inherent theoretical ambiguities is given. The various physical…
The decay constants of the charmed heavy pseudoscalar D and D_s mesons are revisited within a recently developed novel approach to dispersive QCD sum rules which relies on an unprejudiced implementation of quark-hadron duality. The proposed…
We perform pQCD analysis of the existing DIS data for charged leptons with account of corrections up to the NNLO. The parton distributions, value of strong coupling constant, and high-twist terms are extracted and their stability with…
The gauge invariant operator formulation of the angular momentum sum rule ${1\over2} = J_q + J_g$ for the proton is presented and contrasted with the sum rule for the first moment of the polarised structure function $g_1^p$. The decoupling…
Vector mesons show up in the electromagnetic current-current correlator. QCD sum rules provide a constraint on hadronic models for this correlator. This constraint is discussed for the case of finite nuclear density concerning the…
Our knowledge on the nucleon spin structure has greatly improved over the last twenty years or so, but still many fundamental questions remain unsolved. I will try to review some of the puzzling aspects of the origin of the nucleon spin. I…
Neutrino proton elastic scattering and polarized deep inelastic spin sum rules provide complementary information about the spin structure of the proton. We outline the two approaches and what they may teach us about the transition from…
In this talk, we give a short review of our recent works on studying the singly heavy baryon, doubly heavy baryon, and triply heavy baryon spectra from QCD sum rules.
This talk first discusses some aspects of the chiral expansion with three light flavours related to the (non) applicability of the OZI rule. Next, the extension of ChPT to an effective theory of the full standard model is considered. Some…
We derive QCD sum rules for heavy baryons at leading order in $1/m_Q$ and at next-to-leading order in $\alpha_s$. The calculation involves the evaluation of four different perturbative three-loop diagrams which determine the…
Two topics in heavy quark expansion are discussed. The heavy quark potential in perturbation theory is reviewed in connection to the problem of the heavy quark mass. The nontrivial reason behind the failure of the "potential subtracted"…
We point out subtleties in the previous sum rule calculations of the $\pi NN$ coupling associated with using either the PV or the PS coupling schemes in modeling the phenomenological side. We propose a sum rule which is independent of the…