Related papers: QCD Box Graphs and the Quark-Antiquark Potential
Recent evidence for the top mass in the region of 160 $GeV$ for the first time provides an opportunity to use the full power of relativistic quantum field theoretical methods, available also for weakly bound systems. Because of the large…
The QCD corrections for the box diagrams are revisited for the case of a heavy top quark with $\mt = 174 \GeV$. We resolve first a longstanding discrepancy between two methods of calculation by showing that they give the same results when…
Calculations of radiative corrections to the top quark width are reviewed. QCD effects are discussed for $t-\bar t$ systems produced in $e^+e^-$ annihilation near the energy threshold.}
It is demonstrated how perturbative O(alpha_s^2) relativistic corrections to the non-relativistic stable heavy quark-antiquark production cross section in e^+e^- annihilation based on a Coulombic QCD potential can be systematically…
The leading nonperturbative QCD corrections to the one gluon exchange quark-quark, quark-antiquark and $q \bar{q}$ pair-excitation potentials are derived by using a covariant form of nonlocal two-quark and two-gluon vacuum expectation…
In this talk I briefly review the recent progress in calculation of the high order corrections to the parameters of the nonrelativistic heavy quark-antiquark system in the effective theory approach.
In this paper we review the different relativistic and QED contributions to energies, ionic radii, transition probabilities and Land\'e $g$-factors in super-heavy elements, with the help of the MultiConfiguration Dirac-Fock method (MCDF).…
One-loop QCD corrections to the full gauge invariant set of electroweak diagrams describing the charged current processes $e^+ e^- \to u \bar d \mu \bar\nu_\mu$ (CC10), $e^+ e^- \to u \bar d e^- \bar\nu_e$ (CC20) and $e^+ e^- \to u \bar d s…
In the framework of the QCD effective field theory called potential Non-Relativistic QCD, we explore quark-antiquark bound systems that may be dominated by the perturbative interaction and we discuss the extent of validity of such a…
Non-relativistic bound state theories for QED and QCD have become fairly mature and amenable to a textbook-level understanding and computation. In this talk we give an introductory review of the following subjects related to the recent…
We review recent calculations of second order corrections to heavy quark decays. Techniques developed in this context are applicable to many processes involving heavy charged particles, for example the nonabelian dipole radiation.…
The quantum electrodynamics (QED) corrections are directly incorporated into the most accurate treatment of the correlation corrections for ions with complex electronic structure of interest to metrology and tests of fundamental physics. We…
In this talk I review the calculation of the third order corrections to the heavy quarkonium spectrum in the nonrelativistic effective theory framework and its application to the phenomenology of top quark threshold production.
The expected large mass $m_t$ of the top quark provides for the first time a chance to discuss the bound-states of the corresponding quantum system as the nonabelian generalization of positronium, using the full power of relativistic…
We discuss a simple method to evaluate the QCD corrections to $\Delta\rho$. It assumes that the perturbative expansion in terms of $\ms$ parameters is meaningful and, unlike other studies, exploits significant available information…
We calculate the electroweak corrections of the order $O({m_t^2\over v^2})$ to the QCD production of $t\bar{t}$ pairs via $q+qbar->t+tbar$ at hadron colliders and show that these corrections to the total production rate are small. This…
We report on our computation of the mixed QCD and weak corrections to $q {\bar q} \to t\bar{t}$ including $t, \bar t$ spin effects, in particular on single top spin asymmetries.
QCD one-loop corrections to the full gauge invariant set of electroweak diagrams describing the hadronic process $e^+ e^- \to u~\bar d~s~\bar c$ are computed. Four-jet shape variables for $WW$ events are studied at next-to-leading order and…
We evaluate the three-loop corrections to the matching coefficient of the vector current between Quantum Chromodynamics (QCD) and non-relativistic QCD. The result is presented in the MSbar scheme where large perturbative corrections are…
The variational method and the Hamiltonian formalism of QCD are used to derive relativistic, momentum space integral equations for a quark-antiquark system with an arbitrary number of gluons present. As a first step, the resulting infinite…