# Off-shell persistence of composite pions and kaons

## TL;DR

This paper investigates the conditions under which meson poles, specifically for pions and kaons, remain dominant in the quark-antiquark scattering matrix at spacelike momentum transfers, informing experimental approaches.

## Contribution

It delineates the specific momentum transfer ranges where meson poles persist as dominant features, using continuum methods for the strong-interaction bound-state problem.

## Key findings

- Pion pole remains dominant for -t  0.6 GeV^2
- Kaon pole remains dominant for -t  0.9 GeV^2
- Results aid in evaluating experimental feasibility at various facilities.

## Abstract

In order for a Sullivan-like process to provide reliable access to a meson target as $t$ becomes spacelike, the pole associated with that meson should remain the dominant feature of the quark-antiquark scattering matrix and the wave function describing the related correlation must evolve slowly and smoothly. Using continuum methods for the strong-interaction bound-state problem, we explore and delineate the circumstances under which these conditions are satisfied: for the pion, this requires $-t \lesssim 0.6\,$GeV$^2$, whereas $-t\lesssim 0.9\,$GeV$^2$ will suffice for the kaon. These results should prove useful in evaluating the potential of numerous experiments at existing and proposed facilities.