Antihelium-3 production in lead-lead collisions at 158<i>A</i>GeV/<i>c</i>

The NA52 experiment measured particle and antiparticle yields at 0° production angle over a wide range in rapidity in lead-lead (Pb-Pb) collisions at 158 A GeV/c with a minimum bias trigger. Besides (106) antiprotons () and (103) antideuterons () a total of five antihelium-3 () were found. The resulting invariant differential production cross sections at pt≃0 GeV/c turn out to be E (d3σ)/(dp3) = (2.5 ± 1.8) × 10-7 bc3 GeV-2 at a rapidity of y = 3.4 in the laboratory system and (5.9 ± 3.4) × 10-8 bc3 GeV-2 at y = 4.0. The results are discussed in the framework of a simple coalescence model.