Séminaire spécialisé

jeudi 10 janvier 2013 à 11:20

Hadron physics in perturbative QCD

Paul Hoyer

Helsinki University

Hadrons are highly relativistic bound states of QCD, which contain an infinite sea of quark-antiquark pairs. Nevertheless, data shows that hadrons can be classified similarly to atoms, and are qualitatively described by the non-relativistic quark model. I discuss how these features may arise in QCD if the strong coupling freezes in the infrared, αs(Q=0) ≈ 0.5. Hadrons may then be calculated via a perturbative expansion around "Born" states bound only by a linear potential given by Gauss' law for A0. The O(αs0) Born states are Poincare covariant and serve as |in> and <out| states of scattering amplitudes. Their Dirac-type wave functions include quark pair creation/annihilation effects and have a sea-like parton distribution at low xBjorken.