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Register a new userStudy on the resonant parameters of $Y(4220)$ and $Y(4390)$
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Many vector charmonium-like states have been reported recently in the cross sections of $e^+e^- rightarrow omegachi_{c0}$, $pi^{+}pi^{-}h_c$, $pi^{+}pi^{-}J/psi$, $pi^{+}pi^{-}psi(3686)$ and $pi^{+}D^{0}D^{*-}+c.c.$ To better understand the nature of these states, a combined fit is performed to these cross sections by using three resonances $Y(4220)$, $Y(4390)$ and $Y(4660)$. The resonant parameters for the three resonances are obtained. We emphasize that two resonances $Y(4220)$ and $Y(4390)$ are sufficient to explain these cross sections below 4.6 GeV. The lower limits of $Y(4220)$ and $Y(4390)$s leptonic decay widths are also determined to be $(36.4pm2.0pm4.2)$ and $(123.8pm6.5pm9.0)$ eV.
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The vector charmoniumlike state $Y(4220)$ was reported recently in the cross sections of $e^+e^-to omega chi_{c0}$, $pi^+pi^-h_c$, $pi^+pi^- J/psi$, and $D^0 D^{*-}pi^+ + c.c.$ measured by the BESIII experiment. A combined fit is performed to the cross sections of these four final states to extract the resonant parameters of the $Y(4220)$. We determine a mass $M=(4219.6pm 3.3pm 5.1)$~MeV/$c^2$ and a total width $Gamma=(56.0pm 3.6pm 6.9)$~MeV for the $Y(4220)$, where the first uncertainties are statistical and the second ones systematic. Assuming the $Y(4220)$ decays dominantly to the above four modes and their isospin symmetric modes, we also estimate its leptonic decay width and decay branching fractions. These information is essential for the understanding of the nature of this state.
The cross sections of the process $e^{+}e^{-} to eta J/psi$ at center-of-mass energies ($sqrt{s}$) between 3.81 and 4.60 GeV are measured with high precision by using data samples collected with the BESIII detector operating at the BEPCII storage ring. Three structures are observed by analyzing the lineshape of the measured cross sections, and a maximum-likelihood fit including three resonances is performed by assuming the lowest lying structure is the $psi(4040)$. For the other resonances, we obtain masses of $(4218.7 pm 4.0 pm 2.5)$ and $(4380.4 pm 14.2 pm 1.8)$ MeV/c$^{2}$ with corresponding widths of $(82.5 pm 5.9 pm 0.5)$ and $(147.0 pm 63.0 pm 25.8)$ MeV, respectively, where the first uncertainties are statistical and the second ones systematic. The measured resonant parameters are consistent with those of the $Y(4220)$ and $Y(4360)$ from pr evious measurements of different final states. For the first time, we observe the decays of the $Y(4220)$ and $Y(4360)$ into $eta J/psi$ final states.
We study the processes $e^+ e^- to Y(4260) to J/psi pipi(Kbar{K})$. The strong final-state interactions, especially the coupled-channel ($pipi$ and $Kbar{K}$) final-state interaction in the $S$-wave are taken into account in a model-independent way using dispersion theory. It is found that the light-quark SU(3) octet state plays a significant role in these transitions, implying that the $Y(4260)$ contains a large light-quark component. Our findings suggest that the $Y(4260)$ is neither a hybrid nor a conventional charmonium state. Furthermore, through an analysis of the ratio of the light-quark SU(3) octet and singlet components, we show that the $Y(4260)$ does not behave like a pure $bar D D_1$ hadronic molecule as well.
The $Y(4260)$ has been one of the most puzzling pieces among the so-called $XYZ$ states. In this paper, we try to gain insights into the structure of the $Y(4260)$ from the light-quark perspective. We study the dipion invariant mass spectrum of the $e^+ e^- to Y(4260) to J/psi pi^+pi^-$ process and the ratio of the cross sections ${sigma(e^+e^- to J/psi K^+ K^-)}/{sigma(e^+e^- to J/psi pi^+pi^-)}$. In particular, we consider the effects of different light-quark SU(3) eigenstates inside the $Y(4260)$. The strong pion-pion final-state interactions as well as the $Kbar{K}$ coupled channel in the $S$-wave are taken into account in a model-independent way using dispersion theory. We find that the SU(3) octet state plays a significant role in these transitions, implying that the $Y(4260)$ contains a large light-quark component. Our findings suggest that the $Y(4260)$ is neither a hybrid nor a conventional charmonium state, and they are consistent with the $Y(4260)$ having a sizeable $bar D D_1$ component which, however, is not completely dominant.
Inspired by the new resonance $Y(10750)$, we calculate the masses and two-body OZI-allowed strong decays of the higher vector bottomonium sates within both screened and linear potential models. We discuss the possibilities of $Upsilon(10860)$ and $Y(10750)$ as mixed states via the $S-D$ mixing. Our results suggest that $Y(10750)$ and $Upsilon(10860)$ might be explained as mixed states between $5S$- and $4D$-wave vector $bbar{b}$ states. The $Y(10750)$ and $Upsilon(10860)$ resonances may correspond to the mixed states dominated by the $4D$- and $5S$-wave components, respectively. The mass and the strong decay behaviors of the $Upsilon(11020)$ resonance are consistent with the assignment of the $Upsilon(6S)$ state in the potential models.
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