相关论文: The Running Coulomb Potential and Lamb Shift in QC…
We present a calculation scheme for the two-loop vacuum polarization correction of order $\alpha^2$ to the Lamb shift of hydrogen-like high-Z atoms. The interaction with the external Coulomb field is taken into account to all orders in…
Dimensional Reduction is applied to \qcd{} in order to compute various renormalization constants in the \drbar{} scheme at higher orders in perturbation theory. In particular, the $\beta$ function and the anomalous dimension of the quark…
Radiative corrections which remove accidental degeneracy in the spectrum of the relativistic hydrogen atom and lead to the modification of the Coulomb law, are calculated within the novel approach, based on the exact solution of the Dirac…
This lecture provides an introduction to quantum chromodynamics (QCD) on the lattice. The continuum limit and Monte Carlo simulations are briefly discussed. Different facets of QCD are nicely exhibited by the potential of a static quark and…
A physically defined QCD coupling parameter naturally incorporates massive quark flavor thresholds in a gauge invariant, renormalization scale independent and analytical way. In this paper we summarize recent results for the finite-mass…
Quantum point contacts (QPC) are fundamental building blocks of nanoelectronic circuits. For their emission dynamics as well as for interaction effects such as the 0.7-anomaly the details of the electrostatic potential are important, but…
We study the symmetries of the three heavy-quark system under exchange of the quark fields within the effective field theory framework of potential non-relativistic QCD. The symmetries constrain the form of the matching coefficients in the…
We construct the six dimensional Quantum Chromodynamics (QCD) Lagrangian in a linear covariant gauge and subsequently renormalize it at two loops in the MSbar scheme. The coupling constant corresponding to the gauge interaction is…
The QCD analytic running coupling alpha_{an} which has no nonphysical singularities for all Q^2>0 is considered for the initial perturbation theory approximations up to four loop order. The finiteness of the analytic coupling at zero is…
We compute the three-loop QCD corrections to the quark chromomagnetic moment and thus obtain the matching coefficient and the anomalous dimension of the chromomagnetic interaction in HQET. As a byproduct we obtain the three-loop corrections…
We make a review of the different works of Quark Model which are based on Perturbation theory. We make a critical analysis of taking linear part of the Potential as perturbation with Coulombic part as parent and its reverse case. We find in…
For the first time, we compute three-loop contributions to all triple vertices in QCD at the symmetric point. The analytic results are obtained in massless QCD with an arbitrary color group in the Landau gauge. All new loop integrals are…
Quantum electrodynamics (QED) fixed in the 't~Hooft-Veltman gauge is renormalized to three loops in the MSbar scheme. The beta-functions and anomalous dimensions are computed as functions of the usual QED coupling and the additional…
In this work, we analyze the noncommutative three-dimensional Coulomb potential problem. For this purpose, we used the Kustaanheimo-Stiefel mapping to write the Schr\"odinger equation for Coulomb potential in a solvable way. Then, the…
Analytic calculations of the Lamb shift represent a considerable challenge due to the size and the complexity of the expressions that occur in intermediate steps. In the current work, we present a method for the treatment of the bound-state…
The recent determination of the $\beta$--function of the QCD running coupling $\alpha_{\overline{MS}}(Q^2)$ to 5-loops{\color{blue},} provides a verification of the convergence of a novel method for determining the fundamental QCD parameter…
The effective potential has been previously calculated through three-loop order, in Landau gauge, for a general renormalizable theory using dimensional regularization. However, dimensional regularization is not appropriate for softly broken…
Following the procedure and motivations developed by Richardson, Buchmuller and Tye, we derive the potential of static quarks consistent with both the three-loop running of QCD coupling constant under the two-loop perturbative matching of V…
We perform the first study for the heavy-heavy-light quark (QQq) potential in SU(3) lattice QCD. The calculations are done with the standard gauge and $O(a)$-improved Wilson fermion action on the $16^4$ lattice at $\beta =6.0$ at the…
We determine $\Lambda_{\bar{\textrm{MS}}}^{(n_f=2)}$ by fitting perturbative expressions for the quark-antiquark static potential to lattice results for QCD with $n_f=2$ dynamical quark flavors. To this end we use the perturbative static…