A Study of Power Suppressed Contributions in $J/\psi\rightarrow p\bar{p}$ Decay

TL;DR

This paper calculates the power suppressed amplitude involving Pauli coupling in the decay of J/psi to proton-antiproton within an effective field theory, linking it to nucleon distribution amplitudes and analyzing experimental data.

Contribution

It introduces a calculation of the suppressed amplitude in J/psi decay using effective field theory and collinear matrix elements, connecting theory with experimental observations.

Findings

The suppressed amplitude depends on twist-3 and twist-4 nucleon distribution amplitudes.

The contribution is factorisable at leading order.

Qualitative analysis of decay data aligns with the theoretical model.

Abstract

The power suppressed amplitude which describes the Pauli ($\sigma^{\mu\nu}$) coupling in the $J/\psi\to p\bar p$ decay is calculated within the effective field theory framework. It is shown that at the leading-order approximation this contribution is factorisable and the overlap with the hadronic final state can be described by collinear matrix elements. The obtained contribution depends on the nucleon light-cone distribution amplitudes of twist-3 and twist-4. This result is used for a qualitative phenomenological analysis of existing data for $J/\psi\to p\bar p$ decay: branching ratio and the angular distribution in the cross section $e^+e^-\to J/\psi\to p\bar p$.