BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Fawad Hassan (Stockholm University) DTSTART:20200526T130000Z DTEND:20200526T140000Z DTSTAMP:20260423T010754Z UID:MatPhySem/3 DESCRIPTION:Title: Interactions of multiple spin-2 fields: bimetric and multimetric theorie s\nby Fawad Hassan (Stockholm University) as part of Mathematical Phys ics Seminar\n\n\nAbstract\nClassical and quantum fields are classified in terms of their\n"spin" which not only specifies their behavior under rotat ions\, but also\ndetermines the basic structure of their field equations. The Standard\nModel describes particle physics in terms of fields of spin 0\, 1/2 and 1\,\nwhereas General Relativity (GR) is the theory of a single massless field\nof spin 2. Fields of higher spin may not be describable b y local field\ntheories at all\, leaving theories of multiple spin-2 field s as the main\npossible extensions of the familiar field theories. Hence\, a long standing\nquestion has been if GR could be extended to contain ext ra spin 2 fields\nof potential relevant to new physics. The main difficult y in constructing\nsuch theories is the appearance of "ghost" instabilitie s. Some such\ntheories have been found in recent years and are highly cons trained by\nconsistency conditions. This talk describes theories of two an d multiple\nspin-2 fields commonly known as ghost-free bimetric and multim etric\ntheories. In particular I will focus on the structure of ghost free \nbimetric and multimetric interactions\, their physical interpretation\, and\non the notions of space and time in bimetric theories.\n\nWEBINAR ON FRIDAY WAS CANCELLED DUE TO TECHNICAL PROBLEMS\n LOCATION:https://researchseminars.org/talk/MatPhySem/3/ END:VEVENT END:VCALENDAR