Toponium as Nonabelian Positronium ?

The non-invariant energy functional of the preceding paper is improved in order to obtain its gauge-invariant form by strictly taking into account the non-Abelian character of Relativistic Schroedinger Theory (RST). As an application of the results, the dichotomy of positronium with respect to singlet and triplet states is discussed (ortho- and para-positronium). The degeneracy of the ortho- and para-states occurs in RST if (i) the magnetic interactions are neglected (as in t...

We report new aspects of the recent theoretical progress in heavy quarkonium physics. (1) Contrary to wide beliefs, the gross structure of the bottomonium spectrum is described well by the non-relativistic boundstate theory based on perturbative QCD. (2) This leads to a new physical picture of the bottomonium states: the boundstate mass is composed mainly of the self-energies of b and bbar accumulated inside the boundstate. (3) A connection to the conventional phenomenologica...

In this talk we present the current status of the theoretical description of the production of top-quark pairs at the LHC, detailing recent progress for predictions at the stable-top level as well as for predictions that include the decay of the top quarks.

Currently the most precise LHC measurements of the top quark mass are determinations of the top quark mass parameter of Monte-Carlo (MC) event generators reaching uncertainties of well below $1$ GeV. However, there is an additional theoretical problem when using the MC top mass $m_t^{\rm MC}$ as an input for theoretical predictions, because a rigorous relation of $m_t^{\rm MC}$ to a renormalized field theory mass is, at the very strict level, absent. In this talk I show how -...

In these proceedings we present a mini-review on the topic of the Dyson-Schwinger/Bethe-Salpeter approach to the study of relativistic bound-states in physics. In particular, we present a self-contained discussion of their derivation, as well as their truncation such that important symmetries are maintained.

In this paper, the energy levels of the resonant states of toponium, composed of top quark and anti-top quark, are given on the basis of an empirical law. We predict that the mass of the n-th resonant state of toponium is given by Mass(n)=0.81ln}(n) + 347GeV from the empirical law on the resonance level of the bottomonium. The cross-section produced by electron-positron collisions is 3X10^{-9}mb and an electron-positron collider would need an energy of 270GeV X 270 GeV to fin...

It is shown how nonrelativistic QCD (NRQCD) can be used to determine next-to-next-to-leading order relativistic and short-distance contributions to the total $t\bar t$ production cross section in the threshold regime at lepton colliders. A recipe for the calculation of all such contributions for the total photon mediated production cross section is presented and a review of the already known Abelian next-to-next-to-leading results is given.

In this paper, we calculate the toponium spectrum in the potential model with the screened effects. Coulombic part is dominant for toponium, and the coefficient of the Coulomb potential is chosen from lattice QCD calculations at an infinite quark mass in accord with the ultrasoft scale choice. We also derive the relative E1 transitions, decays, and production.

We develop a new nonrelativistic effective field theory of $\rho$NRQCD [1] to describe the finite lifetime effects in the threshold production of top quark-antiquark pairs. The theory is based on the expansion in a parameter $\rho=1-m_W/m_t$ characterizing the dynamics of the top-quark decay. Within this framework we compute the nonresonant contribution to the total cross section of the top quark-antiquark threshold production in electron-positron annihilation up to the next-...

We provide an update on QCD predictions for top-quark pair production close to threshold including bound state effects at the Large Hadron Collider. We compute the top-quark pair invariant mass distribution $d\sigma/dM_{t\bar{t}}$, including Coulomb resummation for bound-state effects, as well as threshold resummation for emissions of soft and collinear gluons. We discuss uncertainty estimates and present a proposal for the use of these predictions in experimental analyses.