Search for the Theta(1540)+ pentaquark using kaon secondary interactions at Belle

TL;DR

This study searches for the Theta(1540)+ pentaquark in kaon interactions at Belle, setting upper limits on its production and decay width, but finds no definitive evidence of its existence.

Contribution

First search for Theta(1540)+ in kaon secondary interactions at Belle, establishing upper limits on production ratios and decay width.

Findings

Upper limit of 2.5% on Theta(1540)+ to Lambda(1520) production ratio.

Upper limit of 0.64 MeV on Theta(1540)+ decay width.

No confirmed detection of Theta(1540)+ in the data.

Abstract

Using kaon secondary interactions in the material of the Belle detector, we search for both inclusive and exclusive production of the Theta(1540)+. We set an upper limit of 2.5% at the 90% C.L. on the ratio of the Theta(1540)+ to Lambda(1520) inclusive production cross sections. We also search for the Theta(1540)+ as an intermediate resonance in the charge exchange reaction K+ n -> p Ks. An upper limit of Gamma(Theta+)<0.64MeV at the 90% C.L. at m(Theta+)=1.539MeV is set. These results are obtained from a 397/fb data sample collected with the Belle detector near the Upsilon(4S) resonance, at the KEKB asymmetric energy e+e- collider.