Reactions gamma gamma -> pi pi and gamma gamma -> K \bar K: the (IJ^{PC}=00^{++})-wave spectra at E_{gamma gamma}^{(c.m.)} = 300- 1900 MeV

Abstract

We calculate the $00^{++}$-wave two-meson spectra for the reactions $\gamma \gamma \to {\pi }^0{\pi }^0$, $\gamma \gamma \to {\pi }^{+}{\pi }^{-}$, $\gamma \gamma \to K^0{\bar{K}}^0$ and $\gamma \gamma \to K^{+}{K}^{-}$ on the basis of: (i) the results of the $K$-matrix analysis of the $00^{++}$ amplitudes for the reactions $\pi \pi \to \pi \pi$, $K\bar{K}$, $\eta \eta$, $\eta {\eta }^{\prime }$, $\pi \pi \pi \pi$, and (ii) recently developed method for calculation of the decay amplitudes $f_0(1^3{P}_{0}q\bar{q})\to \gamma \gamma$, $f_0(2^3{P}_{0}q\bar{q})\to \gamma \gamma$. The reconstructed $\pi \pi$ and $K\bar{K}$ spectra can be used as a guide for the extraction of partial widths of scalar/isoscalar resonances $f_0(980)\to \gamma \gamma$, $f_0(1300)\to \gamma \gamma$, $f_0(1500)\to \gamma \gamma$, $f_0(1750)\to \gamma \gamma$. As follows from our calculations, the resonances $f_0(980)$ and $f_0(1500)$ in the ${\pi }^{+}{\pi }^{-}$ and ${\pi }^0{\pi }^0$ spectra reveal themselves as dips.

Comments: 13 pages, LaTeX, elsart + 7 EPS figures, epsfig.sty