Decay probability ratio of pentaquark Theta(+) state

The pentaquark state of Theta(+)(uudd (s) over bar) has been observed to decay with two decay modes: Theta(+) --> nK(+) and Theta(+) --> pK(0). The decay probability ratio of the two decay modes is studied with general symmetry consideration of isospin, spin and parity. We arrive at a result of the ratio Gamma(Theta(+)-->nK(+))/<(&UGamma;(&UTheta;+ → pK(0)))over bar> = (alpha - beta)(2)/<((α + β)(2))over bar> (k(1/)(k(2)) over bar (2L+1) which is valid for the Theta(+) state to be a pure isoscalar or isovector state, or an isoscalar and isovector mixing state, or an isotensor state with mixture of isoscalar and isovector components with coefficients alpha and beta. The dependence on spin and parity of the pentaquark Theta(+) state is found to be small due to small difference between the center-of-mass decay momenta k(1) and k(2) of the two decay modes. We also provide an analysis on the constraint of the isospin of Theta(+) from the absence of a peak in the pK(+) invariant mass distribution in the gammap --> pK(+)K(-) process. Future experimental results about the decay probability ratio may provide information about the properties of the pentaquark Theta(+) state.Physics, NuclearPhysics, Particles & FieldsPhysics, MathematicalSCI(E)0ARTICLE302289-22971