Search for QCDinstantoninduced effects in deep inelastic electron proton scattering at HE.pdfVIP

Search for QCD-instanton-induced effects in deep inelastic electron proton scattering at HERA∗ Gerd W. Buschhorn Max-Planck-Institut f¨ur Physik 0 (Werner-Heisenberg-Institut) 0 80805 M¨unchen, Germany 0 2 p 1 Introduction e S 6 QCD, in contrast to QED, is not exhausted by perturbation theory. While 1 QCD perturbation theory appears to be very successful at higher momentum v transfers where the strong coupling constant becomes small, some of the 4 most fundamental properties of hadronic physics like color confinement and 6 0 hadronization of quarks and gluons, characteristic for the low momentum 9 transfer region, are not accessible to perturbative methods. 0 0 QCD is a nonabelian gauge theory. In 1975, Polyakov et al. [1] made the im- 0 portant discovery that such theories in their pure gauge form, i.e. without the / h involvement of spontaneous symmetry breaking, have localized classical solu- p - tions in Euclidean space-time. Since the objects described by these solutions p e are localized in 3+1 dimensions, they describe “events” rather than normal h particles which are localized in 3 dimensions. Accordingly, they were named : v pseudoparticles by Polyakov [1] and instantons by ’t Hooft [2]. The replace- i ment of time t by ix (real x ) by going into Euclidean space corresponds X 4 4 r to the method of calculating tunneling amplitudes in the nonperturbative a