Practical Parametrization for Line Shapes of Near-Threshold States

Area of Science:

• * Particle Physics
• * Quantum Chromodynamics
• * Hadron Spectroscopy

Background:

• * Experimental observations reveal numerous quarkonium(like) states near S-wave thresholds.
• * Understanding these states is crucial for advancing hadron spectroscopy and quantum chromodynamics (QCD).

Purpose of the Study:

• * To propose a self-consistent theoretical framework for analyzing near-threshold quarkonium states.
• * To develop an approach compatible with fundamental principles like unitarity and analyticity.
• * To provide a tool for combined analysis of experimental data across various channels.

Main Methods:

• * A coupled-channel system model incorporating a bare pole and multiple elastic/inelastic channels.
• * Full nonperturbative treatment of the coupled-channel dynamics.
• * Derivation of an analytical parametrization for the system's properties.

Main Results:

• * The proposed analytical parametrization successfully describes near-threshold states.
• * The model provides an excellent overall description of experimental data for the charged Z(b)(10610) and Z(b)(10650) states.
• * The framework demonstrates consistency with unitarity and analyticity.

Conclusions:

• * The developed self-consistent approach offers a robust method for studying near-threshold quarkonium(like) states.
• * This theoretical framework is well-suited for combined analyses of diverse experimental data.
• * The successful application to Z(b) states validates the model's predictive power in hadron physics.