The newly observed state Ds0(2590)+

We choose the Reduction Formula, PCAC and Low Energy Theory to reduce the S matrix of a OZI allowed two-body strong decay involving a light pseudoscalar, the covariant transition amplitude formula with relativistic wave functions as input is derived. After confirm this method by the decay D* (2010) -> D pi, we study the newly observed D-s0(2590)(+) with supposing it to be the state D-s(2(1)S(0))(+), we find its decay width Gamma is highly sensitive to the D-s0(2590)(+) mass, which result in the meaningless comparison of widths by different models with various input masses. Instead of width, we studied the overlap integral over the wave functions of initial and final states, here we parameterized it as X which is model-independent, and the ratio Gamma/vertical bar p(f)vertical bar(3), both are almost mass independent, to give us useful information. The results show that, all the existing theoretical predictions X-Ds((2s))-> D*K = 0.25 similar to 0.41 and Gamma/vertical bar p(f)vertical bar(3) = 0.81 similar to 1.77 MeV-2 are smaller than experimental data 0.5850(-0.035)(+0.015) and 4.54(-0.52)(+0.25) MeV-2. Further compared with X-D*(2010)-> D(*)ex = 0.540 +/- 0.009, the current data X-Ds((2s)-> D*)ex K = 0.585(-0.035)(+0.015) Ng is too big to be an reasonable value, so it is early to say D-s0(2590)(+) is the conventional D-s(2(1)S(0))(+) meson.

Automated summary

In this paper, we use the Reduction Formula, PCAC, and Low Energy Theory to study the S matrix of a two-body strong decay involving a light pseudoscalar. We derive the covariant transition amplitude formula with relativistic wave functions as input. After confirming the method with the decay D* (2010) -> D pi, we study the newly observed D-s0(2590)(+) and find that its decay width Gamma is highly sensitive to its mass. Instead of studying the width, we investigate the overlap integral over the wave functions of the initial and final states and parameterize it as X, which is model-independent. Furthermore, we analyze the ratio Gamma/vertical bar p(f)vertical bar(3), both of which are almost mass independent, to provide useful information. The results show that the existing theoretical predictions for X-Ds((2s))-> D*K and Gamma/vertical bar p(f)vertical bar(3) are smaller than the experimental data. Comparing with X-D*(2010)-> D(*)ex, the current data for X-Ds((2s)-> D*)ex K is too big, indicating that it is premature to conclude that D-s0(2590)(+) is the conventional D-s(2(1)S(0))(+) meson.