34,776 research outputs found

    Molecular states with hidden charm and strange in QCD Sum Rules

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    This work uses the QCD Sum Rules to study the masses of the DsDˉs∗D_s \bar{D}_s^* and Ds∗Dˉs∗D_s^* \bar{D}_s^* molecular states with quantum numbers JPC=1+−J^{PC} = 1^{+-}. Interpolating currents with definite C-parity are employed, and the contributions up to dimension eight in the Operator Product Expansion (OPE) are taken into account. The results indicate that two hidden strange charmonium-like states may exist in the energy ranges of 3.83∼4.133.83 \sim 4.13 GeV and 4.22∼4.544.22 \sim 4.54 GeV, respectively. The hidden strange charmonium-like states predicted in this work may be accessible in future experiments, e.g. BESIII, BelleII and SuperB. Possible decay modes, which may be useful in further research, are predicted.Comment: 15 pages, 6 figures, 2 tables, to appear in EP

    Estimating the mass of the hidden charm 1+(1+)1^+(1^{+}) tetraquark state via QCD sum rules

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    By using QCD sum rules, the mass of the hidden charm tetraquark [cu][cˉdˉ][cu][\bar{c}\bar{d}] state with IG(JP)=1+(1+)I^{G} (J^{P}) = 1^+ (1^{+}) (HCTV) is estimated, which presumably will turn out to be the newly observed charmonium-like resonance Zc+(3900)Z_c^+(3900). In the calculation, contributions up to dimension eight in the operator product expansion(OPE) are taken into account. We find m1+c=(3912−153+306) MeVm_{1^+}^c = (3912^{+306}_{-153}) \, \text{MeV}, which is consistent, within the errors, with the experimental observation of Zc+(3900)Z_c^+(3900). Extending to the b-quark sector, m1+b=(10561−163+395) MeVm_{1^+}^b = (10561^{+395}_{-163}) \,\text{MeV} is obtained. The calculational result strongly supports the tetraquark picture for the "exotic" states of Zc+(3900)Z_c^+(3900) and Zb+(10610)Z_b^+(10610).Comment: 13 pages,3 figures, 1 table, version to appear in EPJ

    Mass Spectra of 0+−0^{+-}, 1−+1^{-+}, and 2+−2^{+-} Exotic Glueballs

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    With appropriate interpolating currents the mass spectra of 0+−0^{+-}, 1−+1^{-+}, and 2+−2^{+-} oddballs are studied in the framework of QCD sum rules (QCDSR). We find there exits one stable 0+−0^{+-} oddball with mass of 4.57±0.13 GeV4.57 \pm 0.13 \, \text{GeV}, and one stable 2+−2^{+-} oddball with mass of 6.06±0.13 GeV6.06 \pm 0.13 \, \text{GeV}, whereas, no stable 1−+1^{-+} oddball shows up. The possible production and decay modes of these glueballs with unconventional quantum numbers are analyzed, which are hopefully measurable in either BELLEII, PANDA, Super-B or LHCb experiments.Comment: 10 pages, 12 figures, 4 tables, to appear in NPB. arXiv admin note: substantial text overlap with arXiv:1408.399

    Interpretation of Zc(4025)Z_c(4025) as the Hidden Charm Tetraquark States via QCD Sum Rules

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    By using QCD Sum Rules, we found that the charged hidden charm tetraquark [cu][cˉdˉ][c u][\bar{c} \bar{d}] states with JP=1− J^P = 1^- and 2+ 2^+, which are possible quantum numbers of the newly observed charmonium-like resonance Zc(4025)Z_c(4025), have masses of m1−c=(4.54±0.20) GeVm_{1^-}^c = (4.54 \pm 0.20) \, \text{GeV} and m2+c=(4.04±0.19) GeVm_{2^+}^c = (4.04 \pm 0.19) \, \text{GeV}. The contributions up to dimension eight in the Operator Product Expansion (OPE) were taken into account in the calculation. The tetraquark mass of JP=2+J^{P} = 2^{+} state was consistent with the experimental data of Zc(4025)Z_c(4025), suggesting the Zc(4025)Z_c(4025) state possessing the quantum number of JP=2+J^P = 2^+. Extending to the b-quark sector, the corresponding tetraquark masses m1−b=(10.97±0.25) GeVm_{1^-}^b = (10.97 \pm 0.25) \, \text{GeV} and m2+b=(10.35±0.25) GeVm_{2^+}^b = (10.35 \pm 0.25) \, \text{GeV} were obtained, which are testable in future B-factories.Comment: 15 pages, 6 figures, to appear in European Physical Journal

    Measuring dynamic oil film coefficients of sliding bearing

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    A method is presented for determining the dynamic coefficients of bearing oil film. By varying the support stiffness and damping, eight dynamic coefficients of the bearing were determined. Simple and easy to apply, the method can be used in solving practical machine problems
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