Alexander A. Penin

Heavy quarkonium physics

This report is the result of the collaboration and research effort of the Quarkonium Working Group over the last three years. It provides a comprehensive overview of the state of the art in heavy-quarkonium theory and experiment, covering quarkonium spectroscopy, decay, and production, the determination of QCD parameters from quarkonium observables, quarkonia in media, and the effects on quarkonia of physics beyond the Standard Model. An introduction to common theoretical and experimental tools is included. Future opportunities for research in quarkonium physics are also discussed.

Quest for precision in hadronic cross sections at low energy: Monte Carlo tools vs. experimental data

We present the achievements of the last years of the experimental and theoretical groups working on hadronic cross section measurements at the low-energy e+e− colliders in Beijing, Frascati, Ithaca, Novosibirsk, Stanford and Tsukuba and on τ decays. We sketch the prospects in these fields for the years to come. We emphasise the status and the precision of the Monte Carlo generators used to analyse the hadronic cross section measurements obtained as well with energy scans as with radiative return, to determine luminosities and τ decays. The radiative corrections fully or approximately implemented in the various codes and the contribution of the vacuum polarisation are discussed.

Potential NRQCD and heavy-quarkonium spectrum at next-to-next-to-next-to-leading order

Abstract The next-to-next-to-next-to-leading order (N 3 LO) Hamiltonian of potential nonrelativistic QCD is derived. The complete matching of the Hamiltonian and the contribution from the ultrasoft dynamical gluons relevant for perturbative bound-state calculations is performed including one-, two-, and three-loop contributions. The threshold expansion is used to disentangle and match contributions of different scales in the effective-theory calculations. As a physical application, the heavy-quarkonium spectrum is obtained at N 3 LO for the case of vanishing QCD beta function. Our results set the stage for a full N 3 LO analysis of the heavy-quarkonium system.

Summing up Subleading Sudakov Logarithms

Abstract. We apply the strategy of regions within dimensional regularization to find functions involved in evolution equations which govern the asymptotic dynamics of the Abelian form factor and four-fermion amplitude in the SU(N) gauge theory in the Sudakov limit up to the next-to-leading logarithmic approximation. The results are used for the analysis of the dominant electroweak corrections to the fermion-antifermion pair production in the

Ultrasoft effects in heavy-quarkonium physics

e^+e^-

Heavy Quarkonium Spectrum at

annihilation at high energy.

{\cal O}(\alpha_s^5m_q)

Abstract In the framework of non-relativistic QCD, we consider a new class of radiative corrections, which are generated at next-to-next-to-next-to-leading order through the chromoelectric dipole interaction of heavy quarkonium with ultrasoft virtual gluons. We provide analytical formulae from which the resulting shifts in the quarkonium energy levels and the wave functions at the origin may be calculated. We discuss the phenomenological implications for the top–antitop and ϒ systems and point out some limitations of describing charmonium using a Coulomb potential.

and Bottom/Top Quark Mass Determination

We present the next-to-next-to-next-to-leading

Next-to-next-to-leading logarithms in four fermion electroweak processes at high-energy

{\cal O}(\alpha_s^5m_q)

Heavy quarkonium spectrum at and bottom/top quark mass determination

result for the ground state energy of a heavy quarkonium system. On the basis of this result we determine the bottom quark mass from