PIRSA:12100040

From Effective Strings to the Simplest theory of Quantum Gravity

(2012). From Effective Strings to the Simplest theory of Quantum Gravity. Perimeter Institute. https://pirsa.org/12100040

From Effective Strings to the Simplest theory of Quantum Gravity. Perimeter Institute, Oct. 23, 2012, https://pirsa.org/12100040 

          @misc{ pirsa_PIRSA:12100040,
            doi = {10.48660/12100040},
            url = {https://pirsa.org/12100040},
            author = {},
            keywords = {Quantum Fields and Strings},
            language = {en},
            title = {From Effective Strings to the Simplest theory of Quantum Gravity},
            publisher = {Perimeter Institute},
            year = {2012},
            month = {oct},
            note = {PIRSA:12100040 see, \url{https://pirsa.org}}
          }
Talk number PIRSA:12100040
DOI 10.48660/12100040
Collection
Talk Type Scientific Series
Subject

Abstract

String-like objects arise in many quantum field theories. Well known examples include flux tubes in QCD and cosmic strings. To a first approximation, their dynamics is governed by the Nambu-Goto action, but for QCD flux tubes numerical calculations of the energy levels of these objects have become so accurate that a systematic understanding of corrections to this simple description is desirable. In the first part of my talk, I discuss an effective field theory describing long relativistic strings. The construction parallels that of the chiral Lagrangian in that it is based on the pattern of symmetry breaking. To compare with previous works, I will present the results of the calculation of the S-matrix describing the scattering of excitations on the string worldsheet. In the second part of my talk, I will discuss critical strings from the same point of view and show that the worldsheet S-matrix in this case is non-trivial but can be calculated exactly. I will show that it encodes the familiar square-root formula for the energy levels of the string, the Hagedorn behavior of strings, and argue that the theory on the string worldsheet behaves like a 1+1 dimensional theory of quantum gravity rather than a field theory. If time permits, I will return to the task of computing the energy levels of flux-tubes using lessons learned from the second part of my talk.