String propagator:
a Loop Space Representation

Stefano Ansoldi, Antonio Aurilia and Euro Spallucci

String Propagator:
a Loop Space Representation
Phys. Rev. D 53 (1996) 870
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Keywords:
closed string, kernel, propagator, functional Schroedinger equation, area variables, loop space.
Project goals:
to obtain a description of closed strings (and other extended objects) considering them as fundamental objects and, thus, not focusing on the dynamics of their constituents (points).
Project results:
determination and solution of the equation for the dynamics of a free closed string in terms of area variables; the propagator is obtained and it turns out to ba a function of Pluecher coordinates describing the motion of the string in loop space.
Short Description.

Starting from the Hamilton-Jacobi formalism, a connection is drawn between the dynamics of a closed string and a description in terms of a functional Schroedinger equation. This functional wave equation is for the string what the Wheeler-de Witt equation is for quantum gravity!
A solution for the functional wave equation, the string propagator, is then derived. It describes the motion of a free string but it does not provide information on the motion of the points that constitute the string. Instead it describes the motion of the shape (in loop space) as a whole. The coordinates of the string are, indeed, area (Pluecker) coordinates, namely the area of the projections of the closed string onto the coordinate planes.

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Stefano Ansoldi
ansoldi@trieste.infn.it