Are Y ( 4260 ) and Z 2 + ( 4250 ) <mml:math xmlns:mml="http://www.w3.org/…
2009; American Physical Society; Volume: 79; Issue: 1 Linguagem: Inglês
10.1103/physrevd.79.014001
ISSN1550-7998
Autores Tópico(s)High-Energy Particle Collisions Research
ResumoIn this work, we have investigated whether $Y(4260)$ and ${Z}_{2}^{+}(4250)$ could be ${D}_{1}D$ or ${D}_{0}{D}^{*}$ molecules in the framework of meson exchange model. The off-diagonal interaction induced by $\ensuremath{\pi}$ exchange plays a dominant role. The $\ensuremath{\sigma}$ exchange has been taken into account, which leads to diagonal interaction. The contribution of $\ensuremath{\sigma}$ exchange is not favorable to the formation of the molecular state with ${I}^{G}({J}^{PC})={0}^{\ensuremath{-}}({1}^{--})$; however, it is beneficial to the binding of the molecule with ${I}^{G}({J}^{P})={1}^{\ensuremath{-}}({1}^{\ensuremath{-}})$. Light vector meson exchange leads to diagonal interaction as well. For ${Z}_{2}^{+}(4250)$, the contribution from $\ensuremath{\rho}$ and $\ensuremath{\omega}$ exchange almost cancels each other. For the currently allowed values of the effective coupling constants and a reasonable cutoff $\ensuremath{\Lambda}$ in the range 1--2 GeV, we find that $Y(4260)$ could be accommodated as a ${D}_{1}D$ and ${D}_{0}{D}^{*}$ molecule, whereas the interpretation of ${Z}_{2}^{+}(4250)$ as a ${D}_{1}D$ or ${D}_{0}{D}^{*}$ molecule is disfavored. The bottom analog of $Y(4260)$ and ${Z}_{2}^{+}(4250)$ may exist, and the most promising channels to discover them are ${\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{\Upsilon}$ and ${\ensuremath{\pi}}^{+}{\ensuremath{\chi}}_{b1}$, respectively.
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