325 research outputs found

    Possible Molecular States of Ds∗Dˉs∗D^{*}_s\bar{D}^{*}_s System and Y(4140)

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    The interpretation of Y(4140) as a Ds∗Dˉs∗D^{*}_s\bar{D}^{*}_s molecule is studied dynamically in the one boson exchange approach, where σ\sigma, η\eta and ϕ\phi exchange are included. Ten allowed Ds∗Dˉs∗D^{*}_s\bar{D}^{*}_s states with low spin parity are considered, we find that the JPC=0++J^{PC}=0^{++}, 1+−1^{+-}, 0−+0^{-+}, 2++2^{++} and 1−−1^{--} Ds∗Dˉs∗D^{*}_s\bar{D}^{*}_s configurations are most tightly bound. We suggest the most favorable quantum numbers are JPC=0++J^{PC}=0^{++} for Y(4140) as a Ds∗Dˉs∗D^{*}_s\bar{D}^{*}_s molecule, however, JPC=0−+J^{PC}=0^{-+} and 2++2^{++} can not be excluded. We propose to search for the 1+−1^{+-} and 1−−1^{--} partners in the J/ψηJ/\psi\eta and J/ψη′J/\psi\eta' final states, which is an important test of the molecular hypothesis of Y(4140) and the reasonability of our model. The 0++0^{++} Bs∗Bˉs∗B^{*}_s\bar{B}^{*}_s molecule is deeply bound, experimental search in the Υ(1S)ϕ\Upsilon(1S)\phi channel at Tevatron and LHC is suggested.Comment: 13 pages,2 figure

    Evidence for two-quark content of f0(980)f_{0}(980) in exclusive b→cb\to c decays

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    Inspired by a large decay branching ratio (BR) of B+→f0(980)K+B^{+}\to f_{0}(980)K^{+} measured by Belle recently, we propose that a significant evidence of the component of nnˉ=(uuˉ+ddˉ)/2n\bar{n}=(u\bar{u}+d\bar{d})/\sqrt{2} in f0(980)f_{0}(980) could be demonstrated in exclusive b→cb\to c decays by the observation of f0(980)f_{0}(980) in the final states Bˉ→D0(∗)π+π−(KK)\bar{B}\to D^{0(*)} \pi^{+} \pi^{-}(KK) and Bˉ→J/Ψπ+π−(KK)\bar{B}\to J/\Psi \pi^{+} \pi^{-}(KK). We predict the BRs of Bˉ→D0(∗)(J/Ψ)f0(980)\bar{B}\to D^{0(*)} (J/\Psi) f_{0}(980) to be O(10−4){\cal {O}}(10^{-4}) (O(10−5){\cal {O}}(10^{-5})) while the unknown wave functions of D(∗)0D^{(*)0} (J/ΨJ/\Psi) are chosen to fit the observed decays of Bˉ→D(∗)0π0(J/ΨK0(∗))\bar{B}\to D^{(*)0} \pi^{0} (J/\Psi K^{0(*)}).Comment: 4 pages, 2 figures, Revtex4, version to appear in PR

    Scalar meson dynamics in Chiral Perturbation Theory

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    A comparison of the linear sigma model (Lσ\sigmaM) and Chiral Perturbation Theory (ChPT) predictions for pion and kaon dynamics is presented. Lowest and next-to-leading order terms in the ChPT amplitudes are reproduced if one restricts to scalar resonance exchange. Some low energy constants of the order p4p^4 ChPT Lagrangian are fixed in terms of scalar meson masses. Present values of these low energy constants are compatible with the Lσ\sigmaM dynamics. We conclude that more accurate values would be most useful either to falsify the Lσ\sigmaM or to show its capability to shed some light on the controversial scalar physics.Comment: 9 pages, REVTeX 4.0. Final version accepted for publicatio

    Structure of the axial-vector meson Ds1(2460)D_{s1}(2460) and the strong coupling constant gDs1D∗Kg_{D_{s1} D^* K} with the light-cone QCD sum rules

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    In this article, we take the point of view that the charmed axial-vector meson Ds1(2460)D_{s1}(2460) is the conventional csˉc\bar{s} meson and calculate the strong coupling constant gDs1D∗Kg_{D_{s1} D^* K} in the framework of the light-cone QCD sum rules approach. The numerical values of strong coupling constants gDs1D∗Kg_{D_{s1} D^* K} and gDs0DKg_{D_{s0} D K} are very large, and support the hadronic dressing mechanism. Just like the scalar mesons f0(980)f_0(980) and a0(980)a_0(980), the scalar meson Ds0(2317)D_{s0}(2317) and axial-vector meson Ds1(2460)D_{s1}(2460) may have small csˉc\bar{s} kernels of the typical csˉc\bar{s} meson size, the strong couplings to the hadronic channels (or the virtual mesons loops) may result in smaller masses than the conventional csˉc\bar{s} mesons in the constituent quark models, and enrich the pure csˉc\bar{s} states with other components.Comment: 17 pages, 7 figures, revised version. In the first version, I take the value fDs1=(0.25±0.02)GeVf_{D_{s1}}= (0.25\pm0.02)GeV in numerical calculation, in the revised version, I take a small value fDs1=(0.225±0.020)GeVf_{D_{s1}}=(0.225 \pm0.020)GeV, the value of the strong coupling constant is also change

    Large Nc and Chiral Dynamics

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    We study the dependence on the number of colors of the leading pi pi scattering amplitude in chiral dynamics. We demonstrate the existence of a critical number of colors for and above which the low energy pi pi scattering amplitude computed from the simple sum of the current algebra and vector meson terms is crossing symmetric and unitary at leading order in a truncated and regularized 1/Nc expansion. The critical number of colors turns out to be Nc=6 and is insensitive to the explicit breaking of chiral symmetry. Below this critical value, an additional state is needed to enforce the unitarity bound; it is a broad one, most likely of "four quark" nature.Comment: RevTeX4, 6 fig., 5 page

    Chiral Lagrangian for strange hadronic matter

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    A generalized Lagrangian for the description of hadronic matter based on the linear SU(3)L×SU(3)RSU(3)_L \times SU(3)_R σ\sigma-model is proposed. Besides the baryon octet, the spin-0 and spin-1 nonets, a gluon condensate associated with broken scale invariance is incorporated. The observed values for the vacuum masses of the baryons and mesons are reproduced. In mean-field approximation, vector and scalar interactions yield a saturating nuclear equation of state. We discuss the difficulties and possibilities to construct a chiral invariant baryon-meson interaction that leads to a realistic equation of state. It is found that a coupling of the strange condensate to nucleons is needed to describe the hyperon potentials correctly. The effective baryon masses and the appearance of an abnormal phase of nearly massless nucleons at high densities are examined. A nonlinear realization of chiral symmetry is considered, to retain a Yukawa-type baryon-meson interaction and to establish a connection to the Walecka-model.Comment: Revtex, submitted to Phys. Rev.

    DsD_s decays into Ï•\phi and f0(980)f_0(980) mesons

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    We consider the nonleptonic and semileptonic decays of DsD_s-mesons into ϕ\phi and f0(980)f_0(980) mesons. QCD sum rules are used to calculate the form factors associated with these decays, and the correspondig decay rates. On the basis of data on Ds+→π+π+π−D_s^+\to\pi^+\pi^+\pi^-, which goes dominantly via the transition Ds+→π+f0(980)D_s^+\to \pi^+f_0(980), we conclude that there is space for a sizeable light quark component on f0(980)f_0(980).Comment: 14 pages, RevTeX4 including 5 figures in ps file

    Radiative decays of light vector mesons in a quark level linear sigma model

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    We calculate the P0 to gamma gamma, V0 to P0 gamma and V0to V'0 gamma gamma decays in the framework of a U(3)xU(3) linear sigma model which includes constituent quarks. For the first two decays this approach improves results based on the anomalous Wess-Zumino term, with contributions due to SU(3) symmetry breaking and vector mixing. The phi to (omega,rho) gamma gamma decays are dominated by resonant eta' exchange . Our calculation for the later decays improves and update similar calculations in the -closely related- framework of vector meson dominance. We obtain BR(phi to rho gamma gamma)=2.5x10^{-5} and BR(phi to omega gamma gamma)=2.8x10^{-6} within the scope of the high-luminosity phi factories.Comment: 8 pages, submitted to Phys. Rev.
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