Effective String Amplitudes for Hadronic Physics

TL;DR

This paper explores effective string theory amplitudes for hadronic processes using conformal field theory, proposing mechanisms for chiral symmetry breaking and deriving form factors, thus connecting string models with hadronic phenomenology.

Contribution

It introduces a novel approach to modeling hadronic processes with effective string amplitudes, including mechanisms for chiral symmetry breaking and form factor derivations.

Findings

Rederived hadronic mass relations using string boundary vertex operators.

Derived the structure of the pomeron emission form factor from a string perspective.

Reconciled the pomeron as a closed string with additive quark rules for cross sections.

Abstract

We propose using the general structure and properties of conformal field theory amplitudes, in particular those defined on surfaces with boundaries, to explore effective string theory amplitudes for some hadronic processes. Two examples are considered to illustrate the approach. In one a natural mechanism for chiral symmetry breaking within the string picture is proposed. One consequence is that the vertex operator for pion emission (at zero momentum) behaves like a world sheet current evaluated on the string boundary. This fact is used to rederive, in a more general setting, hadronic mass relations found in the early days of string theory by Lovelace, and Ademollo, Veneziano and Weinberg. In the second example, we derive the general structure of the form factor for the emission of a pomeron (interpreted as a closed string) from a meson or baryon. The result reconciles the interpretation of the pomeron as a closed string, emitted from the interior of the meson or baryon world sheet, with the additive quark rules for total hadronic cross sections. We also review the difficulties involved in constructing complete effective string theories for hadrons, and comment on the relation between the intercepts of trajectories and the short distance behavior of the underlying theory.