First observation of ${\hat{I}}^3{\hat{I}}^3\to p\bar{p}{K}^{+}{K}^{-}$ and search for exotic baryons in $pK$ systems

Abstract

The process ${\hat{I}}^3{\hat{I}}^3\to p\bar{p}{K}^{+}{K}^{-}$ and its intermediate processes are measured for the first time using a 980~fb${}^{-1}$ data sample collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The production of $p\bar{p}{K}^{+}{K}^{-}$ and a $\hat{I}›(1520{)}^0(\bar{\hat{I}}›(1520{)}^0)$ signal in the $p{K}^{-}$~($\bar{p}{K}^{+}$) invariant mass spectrum are clearly observed. However, no evidence for an exotic baryon near 1540~MeV/$c^2$, denoted as $\hat{I}˜(1540{)}^0$~($\bar{\hat{I}}˜(1540{)}^0$) or $\hat{I}˜(1540{)}^{++}$~($\hat{I}˜(1540{)}^{--}$), is seen in the $p{K}^{-}$~($\bar{p}{K}^{+}$) or $p{K}^{+}$~($\bar{p}{K}^{-}$) invariant mass spectra. Cross sections for ${\hat{I}}^3{\hat{I}}^3\to p\bar{p}{K}^{+}{K}^{-}$, $\hat{I}›(1520{)}^0\bar{p}{K}^{+}+c.c.$ and the products $σ(γγ\to Θ(1540)^0 \bar{p} K^+ +c.c.)\BR(Θ(1540)^0 \to p K^{-})$ and $σ(γγ\to Θ(1540)^{++} \bar{p} K^- +c.c.)\BR(Θ(1540)^{++}\to p K^{+})$ are measured. We also determine upper limits on the products of the $\ddot{I}{‡}_{c0}$ and $\ddot{I}{‡}_{c2}$ two-photon decay widths and their branching fractions to $p\bar{p}{K}^{+}{K}^{-}$ at the 90\% credibility level.

9 pages, 9 figures