Determination of the compositeness of resonances from decays: the case of the $B^0_s\to J/\psi f_1(1285)$

TL;DR

This paper introduces a method to quantify the compositeness of resonances, specifically bound states of hadrons, by analyzing production rates and mass distributions, and applies it to the decay of B_s0 into J/psi and f1(1285).

Contribution

The paper presents a novel approach to measure the compositeness of resonances through combined analysis of production rates and mass distributions, with an application to B_s0 decay.

Findings

The method can determine 1-Z with about 0.1 uncertainty.

Applied to B_s0 decay, it analyzes the K K* mass distribution.

The approach provides a quantitative measure of resonance compositeness.

Abstract

We develop a method to measure the amount of compositeness of a resonance, mostly made as a bound state of two hadrons, by simultaneously measuring the rate of production of the resonance and the mass distribution of the two hadrons close to threshold. By using different methods of analysis we conclude that the method allows one to extract the value of 1-Z with about $0.1$ of uncertainty. The method is applied to the case of the $\bar B^0_s \to J/\psi f_1(1285)$ decay, by looking at the resonance production and the mass distribution of $K \bar K^*$.