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Ricci flows and infinite dimensional algebras
Author(s) -
Bakas I.
Publication year - 2004
Publication title -
fortschritte der physik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.469
H-Index - 71
eISSN - 1521-3978
pISSN - 0015-8208
DOI - 10.1002/prop.200410131
Subject(s) - mathematics , ricci flow , gravitational singularity , pure mathematics , generalization , dissipative system , homogeneous space , mathematical analysis , space (punctuation) , manifold (fluid mechanics) , curvature , ricci curvature , physics , geometry , mechanical engineering , linguistics , philosophy , quantum mechanics , engineering
The renormalization group equations of two‐dimensional sigma models describe geometric deformations of their target space when the world‐sheet length changes scale from the ultra‐violet to the infra‐red. These equations, which are also known in the mathematics literature as Ricci flows, are analyzed for the particular case of two‐dimensional target spaces, where they are found to admit a systematic description as Toda system. Their zero curvature formulation is made possible with the aid of a novel infinite dimensional Lie algebra, which has anti‐symmetric Cartan kernel and exhibits exponential growth. The general solution is obtained in closed form using Bäcklund transformations, and special examples include the sausage model and the decay process of conical singularities to the plane. Thus, Ricci flows provide a non‐linear generalization of the heat equation in two dimensions with the same dissipative properties. Various applications to dynamical problems of string theory are also briefly discussed. Finally, we outline generalizations to higher dimensional target spaces that exhibit sufficient number of Killing symmetries.