A study of the pi^0pi^0 system produced in charge exchange and central collisions

Abstract

A study of the $\pi^0\pi^0$ system produced in charge exchange $\pi^-p$ collisions at 38 and 100 GeV/c and in central $pp$ interactions at 450 GeV/c has been carried out. The $S$ wave has rather a complicated structure in both processes indicating the existence of several scalar resonances. The $f_0(980)$ and $f_0(1500)$ appear as dips at 1 and 1.5 GeV in the $S$ wave for charge exchange reaction, and as shoulders at these masses in the $S$ wave for central production. The production of the $f_0(980)$, $f_0(1300)$ and $f_0(1500)$ in the reaction $pp \to p_f\pi^0\pi^0p_s$ as a function of the $dP_{T}$ kinematical filter shows the behaviour differed from what has been observed for the undisputed $q\bar{q}$ mesons. An extra $f_0(2000)$ state is seen in the $S$ wave for charge exchange reaction as a dip at 2 GeV. Resonances with higher spins, $f_2(1270)$, $f_4(2050)$ and $f_6(2510)$, have also been studied. All the three mesons are produced in the reaction $\pi^-p\to\pi^0\pi^0{n}$ mainly via an one-pion exchange for small $-t$, whereas a natural-parity exchange domimates for large $-t$. The behaviour of the centrally produced $f_2(1270)$ as a function of the $dP_{T}$ is consistent with what has been observed for other $q\bar{q}$ states.