Prediction of an exotic state around 4240 MeV with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>J</mml:mi></mml:mrow><mml:mrow><mml:mi>P</mml:mi><mml:mi>C</mml:mi></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:msup><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math> as the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>C</mml:mi></mml:math>-parity partner of Y(4260) in a molecular picture
Xiang-Kun Dong, Yong-Hui Lin, B. S. Zou
Abstract
The possibility of the Y(4260) being the molecular state of $D{\overline{D}}_{1}(2420)+\mathrm{c}.\mathrm{c}.$ is investigated in the one boson exchange model. It turns out that the potential of ${J}^{PC}={1}^{\ensuremath{-}\ensuremath{-}}$ state formed by $D{\overline{D}}_{1}(2420)+\mathrm{c}.\mathrm{c}.$ is attractive and strong enough to bind them together when the momentum cutoff $\mathrm{\ensuremath{\Lambda}}\ensuremath{\gtrsim}1.4\text{ }\text{ }\mathrm{GeV}$. To produce the Y(4260) with correct binding energy, we need $\mathrm{\ensuremath{\Lambda}}\ensuremath{\approx}2.25\text{ }\text{ }\mathrm{GeV}$. Besides, $D{\overline{D}}_{1}(2420)+\mathrm{c}.\mathrm{c}.$ can also form a state with exotic quantum numbers, ${J}^{PC}={1}^{\ensuremath{-}+}$, and its potential is more attractive than that of the ${J}^{PC}={1}^{\ensuremath{-}\ensuremath{-}}$ state. Therefore, an exotic state with mass around 4240 MeV [called ${\ensuremath{\eta}}_{c1}(4240)$] is expected to exist. Our estimation of the mass of the ${J}^{PC}={1}^{\ensuremath{-}+}$ state in charmonium region is in agreement with those predicted by the chiral quark model and the lattice QCD. The possible decay modes and their relative widths are estimated and the results suggest that this exotic state can be searched for in $\ensuremath{\eta}{\ensuremath{\eta}}_{c}$ and $\ensuremath{\eta}{\ensuremath{\chi}}_{c1}$ channels.