A study of the centrally produced π+π-π+π- channel in pp interactions at 450 GeV/c

Abstract The reaction pp → p f ( π + π − π + π − ) p s has been studied at 450 GeV/c in an experiment designed to search for gl states. A spin analysis has been performed and the dP T filter applied. In addition to the well know f 1 (1285) there is evidence for two J PC = 2 −+ states called the η 2 (1620) and η 2 (1875) and a broad scalar called the f 0 (2000). The production of these states as a function of the dP T kinematical filter shows the behaviour expected for q q states. In contrast, there is evidence for two states at 1.45 GeV and at 1.9 GeV which do not show the behaviour observed for q q states.