[Paper Review] Chiral Perturbation Theory for phi -> rho gamma gamma and phi -> omega gamma gamma

Adam K. Leibovich, Aneesh V. Manohar+1 more|arXiv (Cornell University)|Aug 1, 1995

Particle physics theoretical and experimental studies4 citations

TL;DR

This paper uses chiral perturbation theory to predict differential decay distributions for the rare decays phi → rho γγ and phi → omega γγ, as well as isospin-violating phi → omega π⁰. It demonstrates how experimental data on these decays can constrain couplings in the heavy vector meson chiral Lagrangian, offering a theoretical framework to extract low-energy constants from observable decay rates.

ABSTRACT

We predict differential decay distributions for phi->rho gamma gamma and phi -> omega gamma gamma using chiral perturbation theory. We also consider the isospin violating decay phi -> omega pi^0. Experimental information on these decays can be used to determine couplings in the heavy vector meson chiral Lagrangian.

Motivation & Objective

• To predict differential decay distributions for the rare radiative decays phi → rho γγ and phi → omega γγ using chiral perturbation theory.
• To investigate the isospin-violating decay phi → omega π⁰ as a probe for chiral Lagrangian couplings.
• To provide a theoretical framework linking experimental measurements of these decays to low-energy constants in the heavy vector meson chiral Lagrangian.
• To enable determination of unknown couplings in the effective Lagrangian through comparison with future experimental data.

Proposed method

• Application of chiral perturbation theory to describe strong and electromagnetic interactions in heavy vector meson decays.
• Construction of the heavy vector meson chiral Lagrangian including rho, omega, and phi mesons and their couplings to photons.
• Use of effective field theory techniques to compute decay amplitudes for phi → V γγ (V = rho, omega) at leading order in the chiral expansion.
• Incorporation of isospin-breaking effects via the pion mass splitting and electromagnetic corrections.
• Derivation of differential decay rate distributions in terms of kinematic variables such as photon energy and invariant mass.
• Comparison of theoretical predictions with existing or projected experimental data to extract unknown coupling constants.

Experimental results

Research questions

• RQ1 What are the differential decay distributions for phi → rho γγ and phi → omega γγ predicted by chiral perturbation theory?
• RQ2 How do isospin-violating effects manifest in the decay phi → omega π⁰ within the chiral Lagrangian framework?
• RQ3 Which couplings in the heavy vector meson chiral Lagrangian can be constrained by measuring these rare decays?
• RQ4 To what extent do experimental measurements of these decays provide sensitivity to low-energy constants in the effective theory?
• RQ5 How do electromagnetic and strong interaction contributions interplay in these radiative decays?

Key findings

• The differential decay rate for phi → rho γγ is predicted to exhibit a characteristic energy dependence in the photon spectrum, sensitive to chiral Lagrangian couplings.
• The decay phi → omega γγ is found to proceed via a distinct dynamical structure, with a rate sensitive to the same low-energy constants as phi → rho γγ.
• The isospin-violating decay phi → omega π⁰ is predicted to proceed with a rate that depends on the electromagnetic splitting between the rho and omega mesons and their coupling to photons.
• Theoretical predictions for these decays provide a direct link between observable decay distributions and unknown couplings in the heavy vector meson chiral Lagrangian.
• The framework enables extraction of low-energy constants from future experimental data on these rare decays, offering a precision probe of chiral dynamics.