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

Using kaon secondary interactions in the material of the Belle detector, we search for both inclusive and exclusive production of the Θ(1540)+. We set an upper limit of 2.5% at the 90% C.L. on the ratio of the Θ(1540)+ to Λ(1520) inclusive production cross sections. We also search for the Θ(1540)+ as an intermediate resonance in the charge exchange reaction K+n→pKS0. We set an upper limit of ΓΘ+<0.64MeV at the 90% C.L. for mΘ+=1.539MeV/c2. These results are obtained from a 397fb−1 data sample collected with the Belle detector near the ϒ(4S) resonance, at the KEKB asymmetric energy e+e− collider.