pp annihilation into π+π- and K+K- from atomic p states

Academic Article

Abstract

  • We have obtained the branching ratios for pp annihilation at rest into π+π- and K+K- in a pure pp initial angular momentum state L = 1. A gaseous hydrogen target at normal pressure and temperature was used and events associated with transitions of the antiprotonic atom to the 2p level were selected by detecting the Balmer X-ray series. The branching ratios for pp annihilation into π+π- and K+K- from the 2p state are (4.81 ± 0.49) × 10-3 and (2.87 ± 0.51) × 10-4, respect The pion yield is slightly larger than in liquid hydrogen, where L = 0 annihilation dominates, while the kaon yield is suppressed by a factor of four. Using these and previous data, we derive the branching ratios for pp annihilation into all ππ and KK modes from S and P states. A measurement in gaseous hydrogen, without X-ray requirement, yields the branching ratios (4.30 ± 0.14) × 10-3 and (6.92 ± 0.41) × 10-4. With the known branching ratios of (3.33 ± 0.17) × 10-3 and (1.01 ± 0.05) × 10-3 in liquid hydrogen, we find that (50.3 ± 6.4)% of all annihilations in gas at NTP occur in the initial angular momentum state L = 1. © 1988.
  • Authors

    Published In

  • Nuclear Physics A  Journal
  • Digital Object Identifier (doi)

    Author List

  • Doser M; Botlo M; Ahmad S; Amsler C; Armenteros R; Auld EG; Axen DA; Bailey D; Barlag S; Beer GA
  • Start Page

  • 493
  • End Page

  • 511
  • Volume

  • 486
  • Issue

  • 3-4