Chronology of Milestone Events in Particle Physics - BASILE 1981I
Chronology of Milestone Events in Particle Physics

BASILE 1981I

Basile, M.; Bonvicini, G.; Cara Romeo, G.; Cifarelli, L.; Contin, A.; D'Ali, G.; de Cesare, P.; Esposito, B.; Giusti, P.; Massam, T.; Nania, R.; Palmonari, F.; Sartorelli, G.; Valenti, G.; Zichichi, A.;
Evidence for a New Particle with Naked "Beauty'' and for its Associated Production in High-Energy (p p) Interactions
Lett. Nuovo Cim. 31 (1981) 97;

Summary
Evidence is reported for the existence, with six-standard-deviation significance, of a new particle: the heaviest baryon observed so far, whose mass is measured to be m = (5425+175- 75) MeV/c2. Its width is compatible with zero. It is electrically neutral and it decays into a proton, a Do and a o. This particle is produced in association with a hadronic state whose semi-leptonic decay contains a positive electron. The partial cross section for the observed effect is = (3.8 1.2) 10-35 cm2. The interpretation of these results is in terms of the associated production of naked-"beauty'' states in (p p) interactions at sqrt( s = 62 GeV c.m. energy. The new particle is identified as the first "beauty''-flavoured baryon with quark composition (udb), i.e. the b. The discrimination power of the experiment against "known'' physics is of the order of 10-10.) .

Accelerator CERN-ISR Detectors SFM

Reactions
  p p bottom X 62 GeV (Ecm) cs, mass
  p p p K + e+ X 62 GeV (Ecm) mass
  bottom p Do o X
  b p Do o X

Particles studied
  b ex, mass, pw

Record comments
First indication of the existence of the bottom baryon b.
    
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