Antideuteron yield and coalescence implications at the AGS Original Research Article

We present the preliminary results of Experiment 864ʹs search for antideuterons in 11.5 GeV/c per nucleon Au + Pt collisions at the AGS. The data represents 14 billion 10% central interactions selectively triggered for events with high mass candidates. Antideuteron invariant yields are found to be 3.5 ± 1.5(stat.)+0.9−0.5(sys.) × 10−8 GeV−2c2 in the rapidity range between y = 1.8 and 2.2 (ycm = 1.6) for 〈pt〉= 0.35 GeV/c and 3.7±2.7(stat.)+1.4−1.5(sys.) × 10−8 GeV−2c2 between rapidities y = 1.4 and 1.8 at 〈pt〉= 0.26 GeV/c. These yields, along with E864 antiproton measurements, lead to a most probable value for the coalescence factor View the MathML source of 4.1 ± 2.9(stat.)+2.3−2.4(sys.) × 10−3 GeV−2c3 after correcting antiproton yields for antihyperon feeddown contributions. Implications for the coalescence model and antimatter annihilation from an antideuteron measurement are also discussed.