Feasibility study of the K<SUP>+</SUP>d → K<SUP>0</SUP>pp reaction for the Θ<SUP>+</SUP> pentaquark

초록

We investigate theoretically the K(0)p invariant mass spectrum of the K(+)d -> K(0)pp reaction and scrutinize how the signal of the "Theta(+)" pentaquark, if it exists, emerges in the K(0)p spectrum. The most prominent advantage of this reaction is that we can clearly assess whether the "Theta(+)" exists or not as a direct-formation production without significant backgrounds, in contrast to other reactions such as photoproduction and pi-induced productions. We show that while the impulse or single-step scattering process can cover the "Theta(+)" energy region with an initial kaon momentum k(lab) approximate to 0.40 GeV/c in the laboratory frame, the contributions from double-step processes may have a potential possibility to reach the "Theta(+)" energy region with a higher kaon momentum k(lab) similar to 1 GeV/c. Assuming that the full decay width of the "Theta(+)" is around 0.5 MeV, we predict that the magnitude of the peak corresponding to the "Theta(+)" is around a few hundred mu b to 1 mb with the momentum of the kaon beam k(lab) approximate to 0.40 GeV/c while it is around less than or similar to 1 mu b with k(lab) approximate to 0.85 GeV/c. Thus, the "Theta(+)" peak is more likely to be seen at k(lab) approximate to 0.40 GeV/c than at k(lab) approximate to 0.85 GeV/c.

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