7,950 research outputs found

    Exotic QQqˉqˉQQ\bar{q}\bar{q}, QQqˉsˉQQ\bar{q}\bar{s} and QQsˉsˉQQ\bar{s}\bar{s} states

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    After constructing the possible JP=0−,0+,1−J^P=0^-, 0^+, 1^- and 1+1^+ QQqˉqˉQQ\bar{q}\bar{q} tetraquark interpolating currents in a systematic way, we investigate the two-point correlation functions and extract the corresponding masses with the QCD sum rule approach. We study the QQqˉqˉQQ\bar{q}\bar{q}, QQqˉsˉQQ\bar{q}\bar{s} and QQsˉsˉQQ\bar{s}\bar{s} systems with various isospins I=0,1/2,1I=0, 1/2, 1. Our numerical analysis indicates that the masses of doubly-bottomed tetraquark states are below the threshold of the two bottom mesons, two bottom baryons and one doubly bottomed baryon plus one anti-nucleon. Very probably these doubly-bottomed tetraquark states are stable.Comment: 37 pages, 2 figure

    Implications of chiral symmetry on SS-wave pionic resonances and the scalar charmed mesons

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    The chiral symmetry of QCD requires energy-dependent pionic strong interactions at low energies. This constraint, however, is not fulfilled by the usual Breit--Wigner parameterization of pionic resonances, leading to masses larger than the real ones. We derive relations between nonleptonic three-body decays of the BB-meson into a DD-meson and a pair of light pseudoscalar mesons based on SU(3) chiral symmetry. Employing effective field theory methods, we demonstrate that taking into account the final-state interactions, the experimental data of the decays B−→D+π−π−B^-\to D^+\pi^-\pi^-, Bs0→Dˉ0K−π+B_s^0\to \bar{D}^0K^-\pi^+, B0→Dˉ0π−π+B^0\to\bar{D}^0\pi^-\pi^+, B−→D+π−K−B^-\to D^+\pi^-K^- and B0→Dˉ0π−K+B^0\to\bar{D}^0\pi^-K^+ can all be described by the nonperturbative π/η/K\pi/\eta/K-D/DsD/D_s scattering amplitudes previously obtained from a combination of chiral effective field theory and lattice QCD calculations. The results provide a strong support of the scenario that the broad scalar charmed meson D0∗(2400)D^\ast_0(2400) should be replaced by two states, the lower one of which has a mass of around 2.1 GeV, much smaller than that extracted from experimental data using a Breit--Wigner parameterization.Comment: 26 pages, 9 figuere

    One-loop renormalization of the chiral Lagrangian for spinless matter fields in the SU(N) fundamental representation

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    We perform the leading one-loop renormalization of the chiral Lagrangian for spinless matter fields living in the fundamental representation of SU(N). The Lagrangian can also be applied to any theory with a spontaneous symmetry breaking of SU(N)L×SU(N)RSU(N)_L\times SU(N)_R to SU(N)VSU(N)_V and spinless matter fields in the fundamental representation. For QCD, the matter fields can be kaons or pseudoscalar heavy mesons. Using the background field method and heat kernel expansion techniques, the divergences of the one-loop effective generating functional for correlation functions of single matter fields are calculated up to O(p3)\mathcal{O}(p^3). They are absorbed by counterterms not only from the third order but also from the second order chiral Lagrangian.Comment: 13 page

    D∗Dˉ∗D^*\bar D^* molecule interpretation of Zc(4025)Z_c(4025)

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    We have used QCD sum rules to study the newly observed charged state Zc(4025)Z_c(4025) as a hidden-charm D∗Dˉ∗D^*\bar D^* molecular state with the quantum numbers IG(JP)=1+(1+)I^G(J^{P})=1^+(1^{+}). Using a D∗Dˉ∗D^*\bar D^* molecular interpolating current, we have calculated the two-point correlation function and the spectral density up to dimension eight at leading order in αs\alpha_s. The extracted mass is mX=(4.04±0.24)m_X=(4.04\pm0.24) GeV. This result is compatible with the observed mass of Zc(4025)Z_c(4025) within the errors, which implies a possible molecule interpretation of this new resonance. We also predict the mass of the corresponding hidden-bottom B∗Bˉ∗B^*\bar B^* molecular state: mZb=(9.98±0.21)m_{Z_b}=(9.98\pm0.21) GeV.Comment: 6 pages, 5 figures. Version appears in Eur. Phys. J.

    One-loop analysis of the interactions between charmed mesons and Goldstone bosons

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    We derive the scattering amplitude for Goldstone bosons of chiral symmetry off the pseudoscalar charmed mesons up to leading one-loop order in a covariant chiral effective field theory, using the so-called extended-on-mass-shell renormalization scheme. Then we use unitarized chiral perturbation theory to fit to the available lattice data of the S-wave scattering lengths. The lattice data are well described. However, most of the low-energy constants determined from the fit bear large uncertainties. Lattice simulations in more channels are necessary to pin down these values which can then be used to make predictions in other processes related by chiral and heavy quark symmetries.Comment: 34 pages, 7 figures, 7 tables, the final version to be published in JHE

    Possible JPC=0+−J^{PC} = 0^{+-} Exotic State

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    We study the possible exotic states with JPC=0+−J^{PC} = 0^{+-} using the tetraquark interpolating currents with the QCD sum rule approach. The extracted masses are around 4.85 GeV for the charmonium-like states and 11.25 GeV for the bottomomium-like states. There is no working region for the light tetraquark currents, which implies the light 0+−0^{+-} state may not exist below 2 GeV.Comment: 13 pages, 11 figures, 2 table

    Study of open-charm 0+0^+ states in unitarized chiral effective theory with one-loop potentials

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    Chiral potentials are derived for the interactions between Goldstone bosons and pseudoscalar charmed mesons up to next-to-next-to-leading order in a covariant chiral effective field theory with explicit vector charmed-meson degrees of freedom. Using the extended-on-mass-shell scheme, we demonstrate that the ultraviolet divergences and the so-called power counting breaking terms can be properly absorbed by the low-energy constants of the chiral Lagrangians. We calculate the scattering lengths by unitarizing the one-loop potentials and fit them to the data extracted from lattice QCD. The obtained results are compared to the ones without an explicit contribution of vector charmed mesons given previously. It is found that the difference is negligible for SS-wave scattering in the threshold region. This validates the use of D∗D^\ast-less one-loop potentials in the study of the pertinent scattering lengths. We search for dynamically generated open-charm states with JP=0+J^P=0^+ as poles of the SS-matrix on various Riemann sheets. The trajectories of those poles for varying pion masses are presented as well.Comment: 25 pages, 6 figures and 5 table

    The third peak structure in the double J/ψJ/\psi spectrum

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    Recently, the CMS and ATLAS collaborations have reported their J/ψJ/ψJ/\psi J/\psi and J/ψψ′J/\psi \psi^\prime invariant mass distributions, respectively, for searching for fully charmed tetraquarks. Both of them reported the existence of a peak structure around 7.2~\gev. In this article, we exhibit the role of the ηc(2S)ηc(2S)\eta_c(2S)\eta_c(2S) channel, which is close to this peak position, by studying the J/ψJ/ψJ/\psi J/\psi and J/ψψ′J/\psi \psi^\prime invariant mass distributions for the potential quantum numbers JPC=0++J^{PC}=0^{++} or 2++2^{++} by considering both the coherence and incoherence with the background contribution. All these frameworks can describe the experimental data very well, however with different pole structures. For instance, in the case of 2++2^{++} description of these structures, there always exists a pole slightly below the J/ψJ/ψJ/\psi J/\psi threshold. For the 0++0^{++} case, a similar pole can also be found below the J/ψJ/ψJ/\psi J/\psi threshold however with a much lower mass. More importantly, the number of the poles is found to be case-dependent. For the 0++0^{++} (2++2^{++}) case, the peak structure around 7.2~\gev can (cannot) be produced due to the presence (absence) of the ηc(2S)ηc(2S)\eta_c(2S)\eta_c(2S) channel. Although the pole positions are case-dependent, the relation between the peak structure in the J/ψJ/ψJ/\psi J/\psi invariant mass distribution and the dip structure in the J/ψψ′J/\psi \psi^\prime invariant mass distribution around 7.2~\gev is unambiguous. We suggest experimentalists to detailed scan both the J/ψJ/ψJ/\psi J/\psi and the J/ψψ′J/\psi \psi^\prime invariant mass distributions, especially around 7.2~\gev to probe the nature of the third fully charmed state.Comment: 15 pages, 5 figure
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