The Zc±(3900)/Zc±(3885) resonant structure has been experimentally
observed in the Y(4260)→J/ψππ and Y(4260)→Dˉ∗Dπ decays. This structure is intriguing since it is a prominent candidate of
an exotic hadron. Yet, its nature is unclear so far. In this work, we
simultaneously describe the Dˉ∗D and J/ψπ invariant mass
distributions in which the Zc peak is seen using amplitudes with exact
unitarity. Two different scenarios are statistically acceptable, where the
origin of the Zc state is different. They correspond to using energy
dependent or independent Dˉ∗DS-wave interaction. In the first one,
the Zc peak is due to a resonance with a mass around the DDˉ∗
threshold. In the second one, the Zc peak is produced by a virtual state
which must have a hadronic molecular nature. In both cases the two
observations, Zc±(3900) and Zc±(3885), are shown to have the same
common origin, and a Dˉ∗D bound state solution is not allowed. Precise
measurements of the line shapes around the DDˉ∗ threshold are called for
in order to understand the nature of this state.Comment: 6 pages, 6 figure