Raoul Gatto, reference scientist in the international theoretical physics of the XX century, passed away on September 30^{th}. He was at Frascati in two distinct periods, in the early sixties and in the years 1971-1974. During his first period he mainly worked with Nicola Cabibbo and his students on the weak and strong interactions. In particular, in 1961, he wrote a monumental paper with Cabibbo on the phenomenology of the Electron Positron Colliding Beam Experiments, anticipating the physics of the e^{+}e^{– }collider Adone which was going to be built at Frascati. During the second period, after some time spent at CERN, while returning to Rome University, he proposed to a group including Sergio Ferrara, Aurelio Grillo and Giorgio Parisi to investigate the consequences of Conformal Invariance in Quantum Field Theory, as suggested by the Bjorken scaling observed in experiments at SLAC.

In this rapidly expanding subject, in May 1972, Gatto organized at Frascati an International Conference on “Scale and Conformal Symmetry in Hadron Physics” in the framework of the “LNF Advanced School of Physics”. Among the contributions to the conference proceedings the one by Bardeen, Fritzsch, Gell-Mann was particularly relevant since it introduced QCD (the gauge theory of quarks and gluons) and its motivations for being the correct theory of strong interactions.

Raoul then switched from phenomenology to more formal theory, but by no means with less important results. In fact in 1973, with his group at Frascati (at the time Laboratori Nazionali di Frascati del CNEN), he formulated the so-called “Conformal Bootstrap”, using techniques of conformal symmetry imposed on OPE’s (operator product expansions) in conjunction with causality and locality. One year later the Conformal Bootstrap was further developed by the then Soviet physicist Alexander Polyakov, now at Princeton.

The Conformal Bootstrap Program is a method which aims to solve relativistic quantum theories which are not Lagrangian in a non-perturbative fashion. In two space-time dimensions it is deeply related to String Theory.

The “Conformal Bootstrap Program” is nowadays an important area of activity of Theoretical Physics. The pioneering work of Raoul Gatto in the early seventies at Frascati has finally obtained a long due recognition in the recent literature.

*Translation by Camilla Paola Maglione, Communications Office INFN-LNF *