Objective The objective of the project is an increase of the understanding of som non perturbative aspects of quantum field theories such as instanton effects, renormalons and the possibility of its reconstruction by use of resummation techniques. The possibility of the observation of instanton mediated chirality changing processes is strongly suggested by the theoretical results obtained in the analog problem of electroweak instanton induced fermion number violation (to which I devoted some work), together with the largeness of the strong coupling at small scales. The physical comprehension of the renormalons effects (in particular of IR renormalons) is an urgent problem that recently have been treated by many interesting pioneering works that we think should be pursued on. The lack of Borel summability of Q.C.D. and of many others quantum fiel theories motivates the research of new resummation techniques. The Delta Expansion - Order Dependent Mapping is one such technique that gives convergent approximations and allow to treat some quantum cases otherwise non Borel summable: we retain that the possibility of its extension (in particular to four dimensional field theories) is worth studing. Fields of science natural sciencesphysical sciencestheoretical physicsparticle physicsfermionsnatural sciencesphysical sciencesquantum physicsquantum field theory Programme(s) FP4-TMR - Specific research and technological development programme in the field of the training and mobility of researchers, 1994-1998 Topic(s) 0302 - Post-doctoral research training grants TP01 - Elementary Particles and Fields Call for proposal Data not available Funding Scheme RGI - Research grants (individual fellowships) Coordinator Commissariat à l'Energie Atomique (CEA) EU contribution No data Address Centre d'Études de Saclay 91191 Gif-sur-Yvette France See on map Total cost No data Participants (1) Sort alphabetically Sort by EU Contribution Expand all Collapse all Not available Italy EU contribution No data Address See on map Total cost No data