Measurement Of The Kaonic Hydrogen X-Ray Spectrum

The DEAR (DAΦNE exotic atom research) experiment measured the energy of x rays emitted in the transitions to the ground state of kaonic hydrogen. The measured values for the shift ϵ and the width Γof the 1s state due to the K−p strong interaction are ϵ1s=−193±37 (stat) ±6 (syst) eV and Γ1s=249±111 (stat) ±30 (syst) eV, the most precise values yet obtained. The pattern of the kaonic hydrogen K-series lines, Kα, Kβ, and Kγ, was disentangled for the first time.