Studying the D1D molecule in the Bethe-Salpeter equation approach
Abstract
We study the possible bound states of the D1D system in the Bethe-Salpeter (BS) formalism in the ladder and instantaneous approximations. By solving the BS equation numerically with the kernel containing one-particle exchange diagrams and introducing three different form factors (monopole, dipole, and exponential form factors) at the vertices, we investigate whether the isoscalar and isovector D1D bound states may exist, respectively. We find that Y(4260) could be accommodated as a D1D molecule, whereas the interpretation of Z2+(4250) as a D1D molecule is disfavored. The bottom analog of Y(4260) may exist but that of Z2+(4250) does not.
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