Analysis of the charmonium-like states X~*(3860), X(3872), X(3915),X(3930) and X(3940) according to their strong decay behaviors

Inspired by the newly observed state X~*(3860), we analyze the strong decay behaviors of some charmoniumlike states, X~*(3860), X(3872), X(3915), X(3930) and X(3940), with the ~3P_0 model. We carry out our work based on the hypothesis that all of these states are charmonium systems. Our analysis indicates that, as a 0~(++) charmonium state, X~*(3860) can reproduce the experimental data. As for X(3872), it can tentatively be interpreted as the mixture0 of a cc system and a D~*D~0 molecular state. If we consider X(3940) as a 3~1 S_0 state, its total width in the present work is much lower than the experimental result. Thus, the 3~1 S_0 charmonium state seems not to be a good candidate for X(3940). Furthermore, our analysis implies that it is reasonable to assign X(3915) and X(3930) to be the same state, 2~(++). However, combining our analysis with that in Refs.[14, 71], we speculate that X(3915)/X(3930) might also be the mixture of a cc system and a molecular state.     

Oddball Y(4140)as the molecular cousin of Y(3930)

In my talk,we present the dynamical study of Y(4140)and Y(3930)under the D*s(D)*s and D*(D)*molecular assignments respectively.The importance to theoretically and experimentally study their open-charm decay,hidden-charm decay,radiative decay and double-photon decay is proposed combing with the theoretical calculation of the decay behavior of Y(4140)and Y(3930).According to the recent new experimental progress made by Belle,we further indicate the reasonability of molecular explanation to Y(4140).Another event cluster around 4270 MeV in the J/ψφ invariant mass spectrum of B → KJ/ψφ can provide us more hints to reveal the creation mechanism of molecular structure in B meson decay,which will be helpful to clarify the underlying structure of Y(4140)and Y(3930).     

Meson resonances in the open and hidden charm sectors

We briefly present our model for generating open and hidden charm resonances and present the most interesting results.     

Axial resonances in the open and hidden charm sectors

A SU(4) flavor symmetrical Lagrangian is constructed for the interaction of the pseudo-scalar mesons with the vector mesons. SU(4) symmetry is broken to SU(3) by suppression of terms in the Lagrangian where the interaction should be driven by charmed mesons. Chiral symmetry can be restored by setting this new SU(4) symmetry-breaking parameters to zero. Unitarization in coupled channels leads to the dynamical generation of resonances. Many known axial resonances can be identified including the new controversial X(3872) and the structure found recently by Belle around 3875MeV in the hidden charm sector. Also new resonances are predicted, some of them with exotic quantum numbers.     

Production of the X( 3872) in B-meson decay by the coalescence of charm mesons

If the recently discovered charmonium state X( 3872) is a loosely bound S-wave molecule of the charm mesons D0 D(*0) or D(*0) D0, it can be produced in B-meson decay by the coalescence of charm mesons. If this coalescence mechanism dominates, the ratio of the differential rate for B+ -->D(0) D(* 0)K+ near the D0 D(*0) threshold and the rate for B+ -->XK+ is a function of the D0 D(*0) invariant mass and hadron masses only. The identification of the X( 3872) as a D0 D(*0)/D(*0)D0 molecule can be confirmed by observing an enhancement in the D0 D(*0) invariant mass distribution near the threshold. An estimate of the branching fraction for B+ -->XK+ is consistent with observations if X has quantum numbers J(PC)=1(++ ) and if J/psi pi(+) pi(-) is one of its major decay modes.     

Z c (4025) as the hadronic molecule with hidden charm

We have studied the loosely bound $D^{*}\bar{D}^{*}$ system. Our results indicate that the recently observed charged charmonium-like structure Z _c (4025) can be an ideal $D^{*}\bar{D}^{*}$ molecular state. We have also investigated its pionic, dipionic, and radiative decays. We stress that both the scalar isovector molecular partner Z _c0 and three isoscalar partners ${\tilde{Z}}_{c0,c1,c2}$ should also exist if Z _c (4025) is a $D^{*}\bar{D}^{*}$ molecular state in the framework of the one-pion-exchange model. Z _c0 can be searched for in the channel e ⁺ e ^?→Y→Z _c0(4025)(ππ)_P-wave where Y can be Y(4260) or any other excited 1^?? charmonium or charmonium-like states such as Y(4360), Y(4660), etc. The isoscalar $D^{*}\bar{D}^{*}$ molecular states ${\tilde{Z}}_{c0,c2}$ with 0⁺(0⁺⁺) and 0⁺(2⁺⁺) can be searched for in the three pion decay channel $e^{+}e^{-}\to Y \to {\tilde{Z}}_{c0,c2} (3\pi)^{I=0}_{\text{P-wave}}$ . The isoscalar molecular state ${\tilde{Z}}_{c1}$ with 0^?(1^+?) can be searched for in the channel ${\tilde{Z}}_{c1}\eta$ . Experimental discovery of these partner states will firmly establish the molecular picture.     

Measurements of the Z partial decay width into c\bar c and multiplicity of charm quarks per b decay

The partial decay width of the Z into quark pair and the number of charm quarks per b decay are measured with the DELPHI detector at LEP 1. Particle identification provides clear , , and signatures. The charm hadron production rate is measured in each channel by a fit to the scaled energy, impact parameter information and the invariant mass spectrum. Two measurements of are presented, from the production rate and from the overall charm counting, including strange charm baryon production, in events. The multiplicity , which includes hidden and strange charm baryon production, is inferred from the charm counting in events. The final results are and . Received: 1 June 1999 / Published online: 8 December 1999     

Charmonium Decays of Y(4260), psi(4160), and psi(4040)

Using data collected with the CLEO detector operating at the CESR e+e- collider at sqrt[s]=3.97-4.26 GeV, we investigate 15 charmonium decay modes of the psi(4040), psi(4160), and Y(4260) resonances. We confirm, at 11 sigma significance, the BABAR Y(4260)-->pi+pi- J/psi discovery, make the first observation of Y(4260)--> pi(0)pi(0) J/psi (5.1 sigma), and find the first evidence for Y(4260)-->K+K- J/psi(3.7 sigma). We measure e+e- cross sections at sqrt[s]=4.26 GeV as sigma(pi+pi- J/psi)=58(+12)(-10)+/-4 pb, sigma(pi(0)pi(0) J/psi)=23(+12)(-8)+/-1 pb, and sigma(K+K- J/psi)=9(+9)(-5)+/-1 pb, in which the uncertainties are statistical and systematic, respectively. Upper limits are placed on other decay rates from all three resonances.     

Radiative pion decay and the SU(3) × SU(3) σ-model

We claim that there is a complete disagreement between the experimental values and those predicted by the SU(3) × SU(3) σ-model for the radiative pion decay.     

Radiative decays of the Z boson

We calculate the Stokes parameters of the photons produced in the decays of neutral vector bosons Z, Z 1+¯1+ and Z q+¯q+, wherel=e, , or , and q is a quark. In the decays of unpolarized Z bosons (with the production of unpolarized leptons or quarks) the nonzero Stokes parameters for ₂ (circularly polarized photons) and ₃ (linearly polarized photons). The magnitude of ₃ does not depend on the parameters of the netural weak current of the leptons and the quarks (if their mass is neglected). The anomalous magnetic moment of the Z boson is studied.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 38–43, February, 1986.     

Radiative X(3872) Decays in Charmonium-Molecule Hybrid Model

We study the radiative decays of the X(3872) in the charmonium-molecule model combined with the quark potential model. We obtain \({\Gamma(X(3872) \to J/\psi \, \gamma) = 29.2\,{\rm keV}}\) and \({\Gamma(X(3872) \to \psi' \, \gamma) = 6.3\,{\rm keV}}\) . The ratio of these two is 0.22, which is much smaller than the BABAR observation. We find that the result is very sensitive to the amount of the \({\chi_{c1}(1P)}\) component in the X(3872).     

Production and decay of the isotope 271 Ds (Z = 110)

Production and decay of the isotope ²⁷¹Ds were studied. The isotope was produced by ²⁰⁸Pb + ⁶⁴Ni ²⁷¹Ds + n reaction. Fourteen -decay chains have been assigned to decays originating from the isotope ²⁷¹Ds. An excitation function of the production of this isotope was measured. The results have provided a good confirmation of production and decay of ²⁷¹Ds reported by Hofmann et al. The presence of an isomeric state in ²⁷¹Ds has been confirmed. The existence of a possible isomeric state in ²⁶⁷Hs is presented.Received: 22 September 2003, Revised: 26 December 2002, Published online: 10 August 2004PACS: 23.60. + e decay - 25.70.-z Low and intermediate energy heavy-ion reactions - 27.90. + b D. Kaji: Present address: Center for Nuclear Science, University of Tokyo, Wako-shi, Saitama 351-0198, Japan.A. Ozawa: Present address: University of Tsukuba, Tsukuba, Ibaragi 3058 577, Japan.     

On the gamma decay of analogue resonances in the58Fe(p, γ)59Co reaction

The spectrum of the delayed light radiation from a pulsed corona discharge in pure argon was investigated in cylindrical geometry. The band-like structure near 309 nm can be attributed to molecular transitions in the OH-radical of the typeA ² Σ ⁺ ?X ² Π(0?0). The weak bands at 337 nm and 357 nm originate from transitions in the N₂ molecule. The molecular states of OH and N₂ are excited by collisions of³P₂-metastable argon atoms (formed in the gas discharge) with H₂O and N₂ molecules present as small impurities. The pressure dependence of the time constant (some 100 μs) of the afterglow is discussed.     

Baryon decay tests of the form of the charm current

We discuss how semi-leptonic decays of charmed baryons can be used to discriminate between different forms of the charm-changing weak current. Some information can be obtained from the energy and invariant mass distributions of the decay products. More sensitive tests can be made using the polarizations of strange baryons such as Λ, Σ or Ξ in the final state. In principle V±A, pure V and pure A coupling types can all be distinguished. Tests using decays of $\text{3}{}^1$ charmed baryons, such as $\text{C}{}_0{}^{\mathrm{+}}\text{→Λ}{}_0\text{l}{}^{\mathrm{+}}\text{ν}$, are more sensitive than those using decays of $\text{6}$ baryons, such as $\text{C}{}_1{}^{\mathrm{++}}\text{→Σ}{}^{\mathrm{+}}\text{l}{}^{\mathrm{+}}\text{ν}$.     

Too many X’s, Y’s and Z’s?

Heavy meson spectroscopy above open flavor thresholds has become a challenge both from the experimental and theoretical points of view. Experimentally, several signals have been interpreted as meson resonances with unusual properties; theoretically, such signals may be identified with meson-meson molecules or compact multiquark structures. We analyze the influence of thresholds on heavy meson spectroscopy comparing different flavor sectors and quantum numbers. The validity of a quark-model picture above open-flavor thresholds would severely restrict the number of channels that may lodge multiquark structures as meson-meson molecules.