662 research outputs found

    Shape mixing dynamics in the low-lying states of proton-rich Kr isotopes

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    We study the oblate-prolate shape mixing in the low-lying states of proton-rich Kr isotopes using the five-dimensional quadrupole collective Hamiltonian. The collective Hamiltonian is derived microscopically by means of the CHFB (constrained Hartree-Fock-Bogoliubov) + Local QRPA (quasiparticle random phase approximation) method, which we have developed recently on the basis of the adiabatic self-consistent collective coordinate method. The results of the numerical calculation show the importance of large-amplitude collective vibrations in the triaxial shape degree of freedom and rotational effects on the oblate-prolate shape mixing dynamics in the low-lying states of these isotopes.Comment: 29 pages, 14 figure

    Relativistic nuclear energy density functional constrained by low-energy QCD

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    A relativistic nuclear energy density functional is developed, guided by two important features that establish connections with chiral dynamics and the symmetry breaking pattern of low-energy QCD: a) strong scalar and vector fields related to in-medium changes of QCD vacuum condensates; b) the long- and intermediate-range interactions generated by one-and two-pion exchange, derived from in-medium chiral perturbation theory, with explicit inclusion of Δ(1232)\Delta(1232) excitations. Applications are presented for binding energies, radii of proton and neutron distributions and other observables over a wide range of spherical and deformed nuclei from 16O^{16}O to 210Po^{210}Po. Isotopic chains of SnSn and PbPb nuclei are studied as test cases for the isospin dependence of the underlying interactions. The results are at the same level of quantitative comparison with data as the best phenomenological relativistic mean-field models.Comment: 48 pages, 12 figures, elsart.cls class file. Revised version, accepted for publication in Nucl. Phys.

    Study of J/ψJ/\psi and ψ(3686)Σ(1385)0Σˉ(1385)0\psi(3686)\rightarrow\Sigma(1385)^{0}\bar\Sigma(1385)^{0} and Ξ0Ξˉ0\Xi^0\bar\Xi^{0}

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    We study the decays of J/ψJ/\psi and ψ(3686)\psi(3686) to the final states Σ(1385)0Σˉ(1385)0\Sigma(1385)^{0}\bar\Sigma(1385)^{0} and Ξ0Ξˉ0\Xi^0\bar\Xi^{0} based on a single baryon tag method using data samples of (1310.6±7.0)×106(1310.6 \pm 7.0) \times 10^{6} J/ψJ/\psi and (447.9±2.9)×106(447.9 \pm 2.9) \times 10^{6} ψ(3686)\psi(3686) events collected with the BESIII detector at the BEPCII collider. The decays to Σ(1385)0Σˉ(1385)0\Sigma(1385)^{0}\bar\Sigma(1385)^{0} are observed for the first time. The measured branching fractions of J/ψJ/\psi and ψ(3686)Ξ0Ξˉ0\psi(3686)\rightarrow\Xi^0\bar\Xi^{0} are in good agreement with, and much more precise, than the previously published results. The angular parameters for these decays are also measured for the first time. The measured angular decay parameter for J/ψΣ(1385)0Σˉ(1385)0J/\psi\rightarrow\Sigma(1385)^{0}\bar\Sigma(1385)^{0}, α=0.64±0.03±0.10\alpha =-0.64 \pm 0.03 \pm 0.10, is found to be negative, different to the other decay processes in this measurement. In addition, the "12\% rule" and isospin symmetry in the J/ψJ/\psi and ψ(3686)ΞΞˉ\psi(3686)\rightarrow\Xi\bar\Xi and Σ(1385)Σˉ(1385)\Sigma(1385)\bar{\Sigma}(1385) systems are tested.Comment: 11 pages, 7 figures. This version is consistent with paper published in Phys.Lett. B770 (2017) 217-22

    Measurement of azimuthal asymmetries in inclusive charged dipion production in e+ee^+e^- annihilations at s\sqrt{s} = 3.65 GeV

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    We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process e+eππXe^+e^-\rightarrow \pi\pi X based on a data set of 62 pb1\rm{pb}^{-1} at the center-of-mass energy s=3.65\sqrt{s}=3.65 GeV collected with the BESIII detector. These asymmetries can be attributed to the Collins fragmentation function. We observe a nonzero asymmetry, which increases with increasing pion momentum. As our energy scale is close to that of the existing semi-inclusive deep inelastic scattering experimental data, the measured asymmetries are important inputs for the global analysis of extracting the quark transversity distribution inside the nucleon and are valuable to explore the energy evolution of the spin-dependent fragmentation function.Comment: 7 pages, 5 figure

    Observation and study of the decay J/ψϕηηJ/\psi\rightarrow\phi\eta\eta'

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    We report the observation and study of the decay J/ψϕηηJ/\psi\rightarrow\phi\eta\eta' using 1.3×1091.3\times{10^9} J/ψJ/\psi events collected with the BESIII detector. Its branching fraction, including all possible intermediate states, is measured to be (2.32±0.06±0.16)×104(2.32\pm0.06\pm0.16)\times{10^{-4}}. We also report evidence for a structure, denoted as XX, in the ϕη\phi\eta' mass spectrum in the 2.02.12.0-2.1 GeV/c2c^2 region. Using two decay modes of the η\eta' meson (γπ+π\gamma\pi^+\pi^- and ηπ+π\eta\pi^+\pi^-), a simultaneous fit to the ϕη\phi\eta' mass spectra is performed. Assuming the quantum numbers of the XX to be JP=1J^P = 1^-, its significance is found to be 4.4σ\sigma, with a mass and width of (2002.1±27.5±21.4)(2002.1 \pm 27.5 \pm 21.4) MeV/c2c^2 and (129±17±9)(129 \pm 17 \pm 9) MeV, respectively, and a product branching fraction B(J/ψηX)×B(Xϕη)=(9.8±1.2±1.7)×105\mathcal{B}(J/\psi\rightarrow\eta{}X)\times{}\mathcal{B}(X\rightarrow\phi\eta')=(9.8 \pm 1.2 \pm 1.7)\times10^{-5}. Alternatively, assuming JP=1+J^P = 1^+, the significance is 3.8σ\sigma, with a mass and width of (2062.8±13.1±7.2)(2062.8 \pm 13.1 \pm 7.2) MeV/c2c^2 and (177±36±35)(177 \pm 36 \pm 35) MeV, respectively, and a product branching fraction B(J/ψηX)×B(Xϕη)=(9.6±1.4±2.0)×105\mathcal{B}(J/\psi\rightarrow\eta{}X)\times{}\mathcal{B}(X\rightarrow\phi\eta')=(9.6 \pm 1.4 \pm 2.0)\times10^{-5}. The angular distribution of J/ψηXJ/\psi\rightarrow\eta{}X is studied and the two JPJ^P assumptions of the XX cannot be clearly distinguished due to the limited statistics. In all measurements the first uncertainties are statistical and the second systematic.Comment: 10 pages, 6 figures and 4 table

    Search for the radiative transitions ψ(3770)γηc\psi(3770)\to\gamma\eta_c and γηc(2S)\gamma\eta_c(2S)

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    By using a 2.92 fb1^{-1} data sample taken at s=3.773\sqrt{s} = 3.773 GeV with the BESIII detector operating at the BEPCII collider, we search for the radiative transitions ψ(3770)γηc\psi(3770)\to\gamma\eta_c and γηc(2S)\gamma\eta_c(2S) through the hadronic decays ηc(ηc(2S))KS0K±π\eta_c(\eta_c(2S))\to K^0_SK^\pm\pi^\mp. No significant excess of signal events above background is observed. We set upper limits at a 90% confidence level for the product branching fractions to be B(ψ(3770)γηc)×B(ηcKS0K±π)<1.6×105\mathcal{B}(\psi(3770)\to\gamma\eta_c)\times \mathcal{B}(\eta_c\to K^0_SK^\pm\pi^\mp) < 1.6\times10^{-5} and B(ψ(3770)γηc(2S))×B(ηc(2S)KS0K±π)<5.6×106\mathcal{B}(\psi(3770)\to\gamma\eta_c(2S))\times \mathcal{B}(\eta_c(2S)\to K^0_SK^\pm\pi^\mp) < 5.6\times10^{-6}. Combining our result with world-average values of B(ηc(ηc(2S))KS0K±π)\mathcal{B}(\eta_c(\eta_c(2S))\to K^0_SK^\pm\pi^\mp), we find the branching fractions B(ψ(3770)γηc)<6.8×104\mathcal{B}(\psi(3770)\to\gamma\eta_c) < 6.8\times10^{-4} and B(ψ(3770)γηc(2S))<2.0×103\mathcal{B}(\psi(3770)\to\gamma\eta_c(2S)) < 2.0\times10^{-3} at a 90% confidence level.Comment: 10 pages, 4 figure

    Observation of Ds+pnˉD^+_s\rightarrow p\bar{n} and confirmation of its large branching fraction

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    The baryonic decay Ds+pnˉD^+_s\rightarrow p\bar{n} is observed, and the corresponding branching fraction is measured to be (1.21±0.10±0.05)×103(1.21\pm0.10\pm0.05)\times10^{-3}, where the first uncertainty is statistical and second systematic. The data sample used in this analysis was collected with the BESIII detector operating at the BEPCII e+ee^+e^- double-ring collider with a center-of-mass energy of 4.178~GeV and an integrated luminosity of 3.19~fb1^{-1}. The result confirms the previous measurement by the CLEO Collaboration and is of greatly improved precision, which may deepen our understanding of the dynamical enhancement of the W-annihilation topology in the charmed meson decays

    Measurement of the e+eπ+π\mathrm e^+\mathrm e^-\rightarrow\mathrm\pi^+\mathrm\pi^- Cross Section between 600 and 900 MeV Using Initial State Radiation

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    We extract the e+eπ+πe^+e^-\rightarrow \pi^+\pi^- cross section in the energy range between 600 and 900 MeV, exploiting the method of initial state radiation. A data set with an integrated luminosity of 2.93 fb1^{-1} taken at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider is used. The cross section is measured with a systematic uncertainty of 0.9%. We extract the pion form factor Fπ2|F_\pi|^2 as well as the contribution of the measured cross section to the leading order hadronic vacuum polarization contribution to (g2)μ(g-2)_\mu. We find this value to be aμππ,LO(600900  MeV)=(368.2±2.5stat±3.3sys)1010a_\mu^{\pi\pi,\rm LO}(600-900\;\rm MeV) = (368.2 \pm 2.5_{\rm stat} \pm 3.3_{\rm sys})\cdot 10^{-10}.Comment: 14 pages, 7 figures, accepted by PL

    Observation of J/ψppˉa0(980)J/\psi \rightarrow p\bar{p}a_{0}(980) at BESIII

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    Using 2.25×1082.25\times10^{8} J/ψJ/\psi events collected with the BESIII detector at the BEPCII storage rings, we observe for the first time the process J/ψppˉa0(980)J/\psi\rightarrow p\bar{p}a_{0}(980), a0(980)π0ηa_{0}(980)\rightarrow \pi^{0}\eta with a significance of 6.5σ6.5\sigma (3.2σ3.2\sigma including systematic uncertainties). The product branching fraction of J/ψppˉa0(980)ppˉπ0ηJ/\psi\rightarrow p\bar{p}a_{0}(980)\rightarrow p\bar{p}\pi^{0}\eta is measured to be (6.8±1.2±1.3)×105(6.8\pm1.2\pm1.3)\times 10^{-5}, where the first error is statistical and the second is systematic. This measurement provides information on the a0a_{0} production near threshold coupling to ppˉp\bar{p} and improves the understanding of the dynamics of J/ψJ/\psi decays to four body processes.Comment: 8 pages, 7 figure
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