Related papers: What could be learnt from Positronium for Quarkoni…
In this talk I summarize our current understanding of quarkonium states above deconfinement based on phenomenological and lattice QCD studies.
A simple model for QCD is presented, which is able to reproduce the meson spectrum at low energy. The model is a Lipkin type model for quarks coupled to gluons. The basic building blocks are pairs of quark-antiquarks coupled to a definite…
A detailed exposition of two-photon decays of P-wave positronium is given to fill an existing gap in the pedagogical literature. Annihilation decay rates of P-wave positronium are negligible compared to the rates of radiative electric…
We compute the energy levels of some of the lower-lying heavy quarkonium states perturbatively up to O(alpha_s^5*m) and O(alpha_s^5*m*log[alpha_s]). Stability of the predictions depends crucially on the unknown 4-loop pole-MSbar mass…
The importance of including colour octet contributions in describing decay and production of quarkonium states is briefly discussed for two cases : the radiative decays of the $\Upsilon$ and the production of $J/\psi$ in the inclusive $B$…
We examine to what extent several recently discovered narrow resonances can be interpreted as conventional $c\bar{c}$ bound states describable using a potential model. In doing so, we use a semirelativistic approach, which includes both the…
Whether in the Standard Model or beyond it, neutrinos contribute to the invisible decay mode of orthopositronium but practically not at all to that of parapositronium. Although this remark does not resolve the orthopositronium decay puzzle,…
I recall the development of quarkonium quantum mechanics after the discovery of $\Upsilon$. I emphasize the empirical approach to determining the force between quarks from the properties of $c\bar{c}$ and $b\bar{b}$ bound states. I review…
For weakly bound quarkonia, we rederive the next-to-leading order cross sections of quarkonium dissociation by partons that include the hard thermal loop (HTL) resummation. Our results calculated with an effective vertex from the…
Positronium, the electron-positron bound state, is described to a good approximation by pure QED. The states of positronium have definite values of C and P. Consequently, positronium is an attractive system for the investigation of possible…
Rigorous QCD predictions for decay rates of the P-wave states of heavy quarkonia are presented. They are based on a new factorization theorem which is valid to leading order in the heavy quark velocity and to all orders in the running…
We construct an effective Lagrangian for the hadronic decays of a heavy excited $s$-wave-spin-one quarkonium into its ground state. We show that reasonable fits to the measured invariant mass spectra in the $J/\psi$ and $\Upsilon$ systems…
These lecture notes focus on the bound state sector of QCD. Motivated by data which suggests that the strong coupling \alpha_s(Q) freezes at low Q, and by similarities between the spectra of hadrons and atoms, I discuss if and how QCD bound…
We study quarkonium correlators and spectral functions at zero and finite temperature in QCD with only heavy quarks using potential models combined with perturbative QCD. First, we show that this approach can describe the quarkonium…
I discuss quarkonium suppression in equilibriated strongly interacting matter. After a brief review of basic features of quarkonium production I discuss the application of recent lattice data on the heavy quark potential to the problem of…
By means of effective field theory techniques, we study the modifications of some properties of weakly coupled heavy quarkonium states propagating through a quark-gluon plasma at temperatures much smaller than the heavy quark mass, m_Q. Two…
We derive a quantum mechanical upper bound on the amount of radiative energy loss suffered by high energy quarks and gluons in nuclear matter. The bound shows that the nuclear suppression observed in quarkonium production at high $x_F$…
A supersymmetric construction of potentials describing the hard core interaction of the neutron-proton system for low energies is proposed. It considers only the binding energy case and uses the approximation of the Yukawa potential given…
A new theoretical method is developed to solve the two-body bound-state Dirac equation for positronium. Only Coulomb potential was included in the Dirac Hamiltonian. It is shown that the two-body Dirac Hamiltonian can be written in the…
A new relativistic method for calculation of positron binding to atoms is presented. The method combines a configuration interaction treatment of the valence electron and the positron with a many-body perturbation theory description of…