Off-shell string physics

TL;DR

This paper explores off-shell extensions of non-critical string theory amplitudes, revealing unique stringy features that challenge existing string field theory approaches and suggesting the need for a new theoretical framework.

Contribution

It demonstrates a method to continue critical string amplitudes off-shell while preserving conformal invariance, and explicitly calculates three-point functions and the tachyon effective potential.

Findings

Off-shell continuations exhibit unusual stringy characteristics.

Explicit three-point function calculations are provided.

The tachyon effective potential at tree level is derived.

Abstract

Recent advances in non-critical string theory allow a unique continuation, preserving conformal invariance, of critical Polyakov string amplitudes to off-shell momenta. These continuations possess 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. Three-point functions are explicitly calculated. The tree-level effective potential is computed for the tachyon. (This preprint includes some computations used to arrive at results mentioned in hep-th/9211016.)