Announcements

Upcoming events for 2014

  • 6th Bethe Center Workshop, September 29th to October 3rd 2014
  • Bethe-Colloquium by Ettore Remiddi, October 16th 2014
  • Bethe-Colloquium by Carsten Urbach, November 13th 2014

Further information will be given as soon as they are available.

6th Bethe Center Workshop
Topological Strings and Applications

29.09.2013 – 03.10.2013
Poster Workshop 2014

The workshop will take place from September 29th to October 3rd. There will be pedagogical introductory lectures each day followed by research talks by the participants. The introductory talks will be

  • Andrea Brini: "Introduction to matrix models"
  • Hans Jockers: "Topological Strings and Effective Interactions"
  • Albrecht Klemm: "Introduction into Refined Topological String Theory"
  • Wolfgang Lerche: "Introduction to Matrix Factorizations and D-branes"
  • Alessandro Tomasiello: "Geometric aspects of supersymmetric field theories on curved manifolds"
The organizing committee consisted of Hans Jockers, Albrecht Klemm, Wolfgang Lerche, and Stefan Theisen.

Bethe Colloquium by Prof. Ettore Remiddi

October 2014
Ross

October's Bethe Colloquium will take place on October 16th (3:15 pm) in Hörsaal I:

  • Ettore Remiddi (INFN, Bologna)
  • The (state of the) art of Feynman graph evaluation - a personal recollection
  • Hörsaal I, Physikalisches Institut

Abstract: After a short presentation of the current situation of the (g-2) of the electron, I will try to describe some of the new tools appeared in the years in the technology of Feynman graph evaluation. The analytical evaluation of the electron (g-2) required new integration techniques (mostly the differentiation of a suitable integral representation before its actual integration), whose repeated use emphasized the relevance of the continuous dimensional regularisation and of the Integration-by-Parts identities for expressing all the terms to be evaluated to the Master Integrals (MI's) of the problem. When applied to the M.I.s, the differentiation-integration technique naturally evolved into a system of first order differential equations, whose investigation brought into the game the good old Euler's variation of constants, repeated integrations, Euler's dilogarithm, Nielsen's polylogarithms - obviously generalised into harmonic polylogarithms HPL's, two-dimensional HPL's, etc. Large (and still growing) sets of amplitudes are nowdays evaluated in terms of HPL's by solving at once the corresponding huge sets of differential equations by iterating, almost algebraically, clever (but rather simple) integrations procedures, which exploit homogeneity properties and/or the Magnus formalism. Despite all that progress, it is not yet clear whether (or how) the approach can be systematically extended to amplitudes with non vanishing internal masses; to illustrate that point, the case of the two loop (sunrise) self-mass graph will be concisely recalled.