Kaonic hydrogen X-ray measurement in SIDDHARTA

TL;DR

The SIDDHARTA experiment measured X-ray transitions in kaonic hydrogen to precisely determine the strong-interaction effects on the atomic energy levels, providing critical data for understanding low-energy kaon-nucleon interactions in QCD.

Contribution

This work presents the most precise measurements of the strong-interaction induced shift and width of the 1s level in kaonic hydrogen, constraining theoretical models of the $ar{K}N$ interaction.

Findings

Precise values of the energy shift and width of the 1s level in kaonic hydrogen.

Constraints on low-energy $ar{K}N$ interaction models.

Enhanced understanding of chiral symmetry breaking in QCD.

Abstract

Kaonic hydrogen atoms provide a unique laboratory to probe the kaon-nucleon strong interaction at the energy threshold, allowing an investigation of the interplay between spontaneous and explicit chiral symmetry breaking in low-energy QCD. The SIDDHARTA Collaboration has measured the $K$-series X rays of kaonic hydrogen atoms at the DA$\Phi$NE electron-positron collider of Laboratori Nazionali di Frascati, and has determined the most precise values of the strong-interaction induced shift and width of the $1s$ atomic energy level. This result provides vital constraints on the theoretical description of the low-energy $\bar{K}N$ interaction.