# Formal Theory and its Applications to the Standard Model and Beyond

**When:**Wednesday, February 04, 2015 at 2:00 pm

**Where:**DA 218

**Speaker**: James Halverson

**Organization**: Kavli Institute for Theoretical Physics, Santa Barbara

**Sponsor**: High Energy Colloqium

A deepened understanding of quantum field theory or string theory has long been a source of interesting new applications in mathematics and physics. In this talk I will present two examples of how recent progress in string theory sheds interesting new light on the standard model and its extensions. In one, I will demonstrate why string theory and quantum field theory play by different sets of rules. The additional rules of string theory can force the existence of new particles that interact via the weak nuclear force, of a type not typical of the most studied extensions of the standard model. Depending on their mass, these particles could be produced and discovered at the LHC. In another, I will demonstrate that when certain strings interact strongly, the symmetry groups SU(3) and SU(2) are distinguished relative to all other SU(N) groups. This mechanism, together with a newly realized symmetry selection principle, may explain why particle interactions are governed specifically by the groups SU(3) and SU(2). New mathematical techniques show that many properties of known standard model particles are automatically realized in this context.