We successfully observed clear K-series kaonic hydrogen X-rays for the first time taking advantage of two charged pions tagging technique and a gaseous hydrogen target. The strong-interaction energy shift and width of 1s state of K −p atom were determined to be ΔE 1s = -323 ± 63 (statistical) ± 11 (systematic) eV and Г1s = 407 ± 208 ± 100 eV. Our result means that the K −p strong interaction near threshold is repulsive and the long-standing kaonic hydrogen puzzle is solved.
KeywordsCharged Pion Titanium Foil Plastic Scintillation Beam Pion Kaonic Hydrogen
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- G.A. Beer, this issue.Google Scholar