# Comparison of the pp -> pi+ pn and pp -> pi+ d production rates

## TL;DR

This paper compares the production rates of pp -> pi+ pn and pp -> pi+ d reactions at low energies using bubble chamber data, revealing deviations from simple models likely due to higher partial waves in the pn system.

## Contribution

It provides a detailed analysis of the ratio of these reactions and highlights the importance of higher partial waves in understanding final state interactions.

## Key findings

- The ratio agrees with high-resolution spectrometer data within tolerances.
- Angular distribution indicates deviations from simple final state interaction predictions.
- Higher partial waves significantly influence the pn system at low energies.

## Abstract

Fully constrained bubble chamber data on the pp -> pi+ pn and pp -> pi+ d reactions are used to investigate the ratio of the counting rates for the two processes at low pn excitation energies. Whereas the ratio is in tolerable agreement with that found in a high resolution spectrometer experiment, the angular distribution in the final pn rest frame shows that the deviation from the predictions of final state interaction theory must originate primarily from higher partial waves in the pn system. These considerations might also be significant for the determination of the S-wave Lambda:p scattering length from data on the pp -> K+ Lambda p reaction.