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Register a new userThe $chi_{cJ}$ decay to $phi K^* bar K, phi h_1(1380)$ testing the nature of axial vector meson resonances
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We perform a theoretical study of the $chi_{cJ} to phi K^* bar K to phi Kpi bar K$ reaction taking into account the $K^* bar K$ final state interaction, which in the chiral unitary approach is responsible, together with its coupled channels, for the formation of the low lying axial vector mesons, in this case the $h_1(1380)$ given the selection of quantum numbers. Based on this picture we can easily explain why in the $chi_{c0}$ decay the $h_1(1380)$ resonance is not produced, and, in the case of $chi_{c1}$ and $chi_{c2}$ decay, why a dip in the $K^+ pi^0 K^-$ mass distribution appears in the 1550-1600 MeV region, that in our picture comes from a destructive interference between the tree level mechanism and the rescattering that generates the $h_1(1380)$ state. Such a dip is not reproduced in pictures where the nominal $h_1(1380)$ signal is added incoherently to a background, which provides support to the picture where the resonance appears from rescattering of vector-pseudoscalar components.
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Using a data sample of 106 million $psi(3686)$ events collected with the BESIII detector operated at the BEPCII storage ring, we study for the first time the decay $chi_{cJ}tophi K^{0}_S K^{pm}pi^{mp}$ and $chi_{cJ}tophi K^{+} K^{-}pi^{0}$ in the E1 radiative transition $psi(3686)togammachi_{cJ}$. The decays are dominated by the three-body decay $chi_{cJ}to phi K^*(892)bar{K}$. We measure branching fractions for this reaction via the neutral and charged $K^*(892)$ and find them consistent with each other within the expectation of isospin symmetry. In the $Kbar{K}pi$ invariant mass distribution a structure near the $K^*(892)bar{K}$ mass threshold is observed, and the corresponding mass and width are measured to be $1412pm4(mathrm{stat.})pm8(mathrm{sys.}) mathrm{MeV}/c^2$ and $Gamma$ = $84pm12(mathrm{stat.})pm40(mathrm{sys.}) mathrm{MeV}$, respectively. The observed state favors an assignment to the $h_1(1380)$, considering its possible $J^{PC}$ and comparing its mass, width and decay mode to those reported in the Particle Data Group.
In this work, we propose that detecting the polarization information of $chi_{cJ}to phiphi~(J=0,1,2)$ can be as good test of the role of hadronic loop effect on these decays. Our results shows that the obtained ratios of helicity amplitudes are quite stable, which are $|F_{1,1}^{(0)}/F_{0,0}^{(0)}| approx 0.359$, $|F_{1,0}^{(1)}/F_{0,1}^{(1)}| =1$, $|F_{1,1}^{(1)}/F_{0,1}^{(1)}| =0$, $|F^{(2)}_{1,0}|/|F^{(2)}_{0,0}|=|F^{(2)}_{0,1}|/|F^{(2)}_{0,0}| approx 1.285,~|F^{(2)}_{1,-1}|/|F^{(2)}_{0,0}|=|F^{(2)}_{-1,1}|/|F^{(2)}_{0,0}| approx 5.110$ and $|F^{(2)}_{-1,-1}|/|F^{(2)}_{0,0}|=|F^{(2)}_{1,1}|/|F^{(2)}_{0,0}| approx 0.465$. By adopting these predicted ratios, we further generate Monte-Carlo events of moments $langle t_{ij} rangle$, which are directly related to the determination of helicity amplitudes. We suggest further experiments like BESIII and Belle II to perform an analysis on the polarizations of the $chi_{cJ}to phiphi$ process in the future, which is important to understand the underlying decay mechanism existing in $chi_{cJ}$ decays.
Using a data sample of $(448.1pm2.9)times10^{6}$ $psi(3686)$ decays collected by the BESIII detector at the Beijing Electron Positron Collider (BEPCII), we observe the decays $chi_{cJ}to phiphieta~(J=0,~1,~2)$, where the $chi_{cJ}$ are produced via the radiative processes $psi(3686)togammachi_{cJ}$. The branching fractions are measured to be $mathcal B(chi_{c0}tophiphieta)=(8.41pm0.74pm0.62)times10^{-4}$, $mathcal B(chi_{c1}tophiphieta)=(2.96pm0.43pm0.22)times 10^{-4}$, and $mathcal B(chi_{c2} to phiphieta)=(5.33pm0.52pm0.39) times 10^{-4}$, where the first uncertainties are statistical and the second are systematic. We also search for intermediate states in the $phiphi$ or $etaphi$ combinations, but no significant structure is seen due to the limited statistics.
We investigate the decay mechanism in the B^- -> phi phi K^- decay with the phi phi invariant mass below the charm threshold and in the neighborhood of the eta_c invariant mass region. Our approach is based on the use of factorization model and the knowledge of matrix elements of the weak currents. For the B meson weak transition we apply form factor formalism, while for the light mesons we use effective weak and strong Lagrangians. We find that the dominant contributions to the branching ratio come from the eta, eta and eta(1490) pole terms of the penguin operators in the decay chains B^- -> eta (eta, eta(1490)) K^- -> phi phi K^-. Our prediction for the branching ratio is in agreement with the Belles result.
Using $1.31 times 10^9$ $J/psi$ events collected by the BESIII detector at the BEPCII $e^+e^-$ collider, we report the first observation of the $h_1(1380)$ in $J/psi to eta^{prime} h_1(1380)$ with a significance of more than ten standard deviations. The mass and width of the possible axial-vector strangeonium candidate $h_1(1380)$ are measured to be $M = (1423.2 pm 2.1 pm 7.3)mevcc$ and $Gamma = (90.3 pm 9.8 pm 17.5)mev$. The product branching fractions, assuming no interference, are determined to be $mathcal{B}(J/psi to eta^{prime}h_1(1380)) times mathcal{B}(h_1(1380) to K^{*}(892)^{+} K^{-} +c.c.) = (1.51 pm 0.09 pm 0.21) times 10^{-4}$ in $eta^{prime}K^+K^-pi^0$ mode and $mathcal{B}(J/psi to eta^{prime}h_1(1380)) times mathcal{B}(h_1(1380) to K^{*}(892)bar K +c.c.) = (2.16 pm 0.12 pm 0.29) times 10^{-4}$ in $eta^{prime}K_S^0K^{pm}pi^{mp}$ mode. The first uncertainties are statistical and the second are systematic. Isospin symmetry violation is observed in the decays $h_1(1380) to K^{*}(892)^{+} K^{-} +c.c.$ and $h_1(1380) to K^{*}(892)^{0}bar K^{0} +c.c.$. Based on the measured $h_1(1380)$ mass, the mixing angle between the states $h_1(1170)$ and $h_1(1380)$ is determined to be $(35.9pm2.6)^{circ}$, consistent with theoretical expectations.
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