Exploring two non-perturbative definitions of CA

Non-Perturbative Two-Dimensional Quantum Gravity, Again

Perturbative and non-perturbative QCD

In these lectures we give a concise introduction to the ideas of renormalon calculus in QED and QCD. We focus in particular on the example of the Adler D function of vacuum polarization, and on relations between perturbative renormalon ambiguities and corresponding non-perturbative Operator Product Expansion (OPE) ambiguities. Recent work on infrared freezing of Euclidean observables is also di...

A Possible Two-component Structure of the Non-perturbative Pomeron

We propose a QCD-inspired two-component Pomeron form which gives an excellent description of the pp, πp, Kp, γp and γγ total cross-sections. Our fit has a better χ/dof for a smaller number of parameters as compared with the PDG fit. Our 2-Pomeron form is fully compatible with weak Regge exchange-degeneracy, universality, Regge factorization and the generalized vector dominance model. LPNHE 00-0...

Perturbative and Non-Perturbative Quarks and Gluons

BRST invariance supplies a sufficient condition for the observability of fields. We show that there is a global obstruction to the observability of quarks and gluons and argue that they will not become observables at finite temperature. We give expressions for quarks and gluons that are, however, perturbatively BRST invariant, and hence locally observable, up to order g and g respectively. 1 e-...

Perturbative and Non - Perturbative Partial Supersymmetry Breaking

We show the existence of a supersymmetry breaking mechanism in string theory, where N = 4 supersymmetry is broken spontaneously to N = 2 and N = 1 with moduli dependent gravitino masses. The spectrum of the spontaneously broken theory with lower supersymmetry is in one-to-one correspondence with the spectrum of the heterotic N = 4 string. The mass splitting of the N = 4 spectrum depends on the ...