Coherent production of the long-lived pionium nP states in relativistic nucleus-nucleus collisions

TL;DR

This paper proposes a method to produce long-lived pionium nP states coherently in relativistic nucleus collisions, aiming to facilitate precise Lamb-shift measurements of pionium atoms.

Contribution

It introduces a general expression for estimating the yield of pionium nP states in relativistic collisions using the equivalent photon approximation.

Findings

Derived a formula for pionium nP state production yield

Suggests a new source for pionium Lamb-shift experiments

Provides theoretical framework for future experimental studies

Abstract

The coherent production of the nP states of the $\pi^+\pi^-$ atoms ($A_{2\pi}$) in relativistic nucleus-nucleus collisions is considered as a possible source of the $A_{2\pi}(nP)$ beam for the pionium Lamb-shift measurement. A general expression for estimation of the $A_{2\pi}(nP)$ yield is derived in the framework of the equivalent photon approximation.