Article révisé par les pairs
Résumé : In a study of the reaction K+p → K Nππ in the 81 cm Saclay hydrogen bubble chamber, exposed at CERN to separated K+ mesons of 3, 3.5 and 5 GeV/c, strong evidence has been found for an enhancement in the mass spectrum of the I-spin 1/2 K* (892)π system. Even though the phenomenon is beyond any statistical doubt, it is difficult and probably not meaningful to assign to it well-defined mass and width values since the enhancement occupies the whole region between 1 and 1.5 GeV/c2 and since the position of the peak appears to move with incident momentum. It is therefore unlikely that the effect is due to a single resonance. An explanation in terms of the peripheral model (Deck mechanism) meets with severe difficulties. An interpretation as a superposition of adjacent resonances seems acceptable as several resonances have been proposed in this mass region. However, since only one of them, the K*(1400), is well established, our effect calls for at least one additional resonance. In the simplest assumption of two adjacent resonances one would be the K*(1400) and the other a K* of mass ≈1270 MeV/c2 with a width ≈200 MeV/c2. © 1967 Società Italiana di Fisica.

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