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

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 Script O(10⁶) antiprotons (bar-p) and Script O(10³) antideuterons (bar-d) a total of five antihelium-3 (overline-3He) were found. The resulting invariant differential overline-3He production cross sections at p_tsimeq0 GeV/c turn out to be E (d³sigma)/(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.