Conformally invariant off-shell string physics

TL;DR

This paper constructs a conformally invariant extension of off-shell string amplitudes, revealing unique stringy features that suggest the need for a new theoretical framework beyond string field theory.

Contribution

It introduces a novel conformally invariant off-shell continuation of Polyakov amplitudes, providing explicit three-point amplitude calculations and highlighting features unlikely to be captured by existing string field theories.

Findings

Off-shell amplitudes exhibit unique stringy characteristics.

The results imply the necessity for a new formulation beyond string field theory.

Explicit three-point amplitude calculations demonstrate the approach's validity.

Abstract

Using recent advances in the understanding of non-critical strings, we construct a unique, conformally invariant continuation to off-shell momenta of Polyakov amplitudes in critical string theory. Three-point amplitudes are explicitly calculated. These off-shell amplitudes possess some unusual, apparently stringy, characteristics, which are unlikely to be reproduced in a string field theory. Thus our results may be an indication that some fundamentally new formulation, other than string field theory, will be required to extend our understanding of critical strings beyond the Polyakov path integral.