FOCUS MEETING "Naturalness and the future of High Energy Physics"

ABSTRACT
Naturalness arguments have been a powerful guiding principle for physicists as they try to construct new theories. While considerations based on simplicity and elegance have characterized the scientific thought since very early times, numerical naturalness, as most clearly formulated by ’t Hooft and Wilson, has been especially influential in the search for theories of fundamental interactions. When applied to our current description of the microscopic world in terms of quantum field theory, it leads to the apparent paradox of the smallness of the electroweak scale and of the cosmological constant as compared to the Planck scale. In this Focus Meeting, Gian Francesco Giudice and Riccardo Rattazzi will review the concept of naturalness and its implications. The seemingly convincing notions of naturalness and simplicity in Effective Field Theory will be introduced and argued that they appear mutually contradictory in both the SM and its natural extensions. This state of things defines the Hierarchy Paradox. The hypotheses on which the naturalness principle rests, the consequences of relaxing some of these hypotheses, and the current attempts to develop new paradigms beyond naturalness will then be discussed.
BIO
Gian Francesco Giudice obtained his PhD in theoretical physics from the International School for Advanced Studies in Trieste. He was Research Associate at Fermilab, University of Texas and INFN. He later moved to CERN, where he is currently the Head of the Theoretical Physics Department. His research mainly deals with formulating new theories of the fundamental interactions and studying their implications for the early universe. He made significant contributions in the areas of supersymmetry, extra dimensions, electroweak physics, collider physics, dark matter, and leptogenesis. Among his most influential works are those on the Giudice-Barbieri criterion to test the degree of naturalness, anomaly mediation, split supersymmetry, the Giudice-Masiero mechanism, Minimal Flavor Violation, the Higgs boson potential and quantum criticality.
BIO
Riccardo Rattazzi obtained his PhD at Scuola Normale Superiore, Pisa, and held postdoctoral positions at Berkeley, Rutgers and CERN. He was then researcher at INFN and junior staff at CERN. Since 2006 he is professor of physics at the École Polytechnique Fédérale de Lausanne. His research is focused on the many aspects of quantum field theory, ranging from particle physics to conformal theories, condensed matter systems, and cosmology. He gave significant contributions to effective field theory, supersymmetry, composite Higgs theories and extra dimensions. His work led to the discovery of anomaly mediation in supersymmetry and of galileon theories, as well as to the first practical implementation of the conformal bootstrap method in four dimensions.