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Träfflista för sökning "WFRF:(Sun Xiao Feng) srt2:(2015-2019);srt2:(2017)"

Sökning: WFRF:(Sun Xiao Feng) > (2015-2019) > (2017)

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  • Föregående 12[3]4Nästa
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21.
  • Ablikim, M., et al. (författare)
  • Measurements of the branching fractions for D+ -> (KSKSK+)-K-0-K-0+, (KSKS0)-K-0 pi + and D-0 -> (KSKS0)-K-0, (KSKSKS0)-K-0-K-0
  • 2017
  • Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 765, s. 231-237
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>By analyzing 2.93 fb(-1) of data taken at the psi(3770) resonance peak with the BESIII detector, we measure the branching fractions for the hadronic decays D+ -&gt; (KSKSK+)-K-0-K-0, D+ -&gt; (KSKS0)-K-0 pi(+), D-0 -&gt; (KSKS0)-K-0 and D-0 -&gt; (KSKSKS0)-K-0-K-0.They are determined to be B(D+ -&gt; (KSKSK+)-K-0-K-0) = (2.54 +/- 0.05(stat.) +/- 0.12(sys.))x 10(-3), B(D+ -&gt; (KSKS0)-K-0 pi(+)) = (2.70 +/- 0.05(stat,) +/- 0.12(sys.)) x 10(-3), B(D+ -&gt; (KSKS0)-K-0) = (1.67 +/- 0.11(stat.) +/- 0.11(sys.)) x 10(-4) and B(D+ -&gt; (KSKSKS0)-K-0-K-0) = (7.21 +/- 0.33(stat.) +/- 0.44(sys,)) x 10(-4), where the second one is measured for the first time and the others are measured with significantly improved precision over the previous measurements.</p>
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22.
  • Ablikim, M., et al. (författare)
  • Observation of e(+)e(-) -&gt; eta h(c) at center-of-mass energies from 4.085 to 4.600 GeV
  • 2017
  • Ingår i: Physical Review D : covering particles, fields, gravitation, and cosmology. - 2470-0010 .- 2470-0029. ; 96:1
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>We observe for the first time the process e(+) e(-) -&gt; eta h(c) with data collected by the BESIII experiment. Significant signals are observed at the center-of-mass energy root s = 4.226 GeV, and the Born cross section is measured to be (9.5(-2.0)(+2.2)) pb. Evidence for eta h(c) is observed at root s = 4.358 GeV with a Born cross section of (10.0(-2.7)(+3.1)) pb, and upper limits on the production cross section at other center-of-mass energies between 4.085 and 4.600 GeV are determined.</p>
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23.
  • Ablikim, M., et al. (författare)
  • Observation of Lambda(+)(c) -&gt; nK(S)(0)pi(+)
  • 2017
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 118:11
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>We report the first direct measurement of decays of the Lambda(+)(c) baryon involving the neutron. The analysis is performed using 567 pb(-1) of e(+)e(-) collision data collected at root s = 4.599 GeV with the BESIII detector at the BEPCII collider. We observe the decay Lambda(+)(c) -&gt; nK(S)(0)pi(+) and measure the absolute branching fraction to be B(Lambda(+)(c) -&gt; nK(S)(0)pi(+)) = [1.82 +/- 0.23(stat) +/- 0.11(syst)]%. A comparison to B[Lambda(+)(c) -&gt; p( (K) over bar pi)(0)] provides an important test of isospin symmetry and final state interactions.</p>
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24.
  • Ablikim, M., et al. (författare)
  • Observation of the helicity-selection-rule suppressed decay of the <em>χ</em><sub>c2</sub> charmonium state
  • 2017
  • Ingår i: Physical Review D : covering particles, fields, gravitation, and cosmology. - AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 96:11
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>The decays of chi(c2) -&gt; K+K- pi(0), KSK +/-pi(-/+), and pi(+)pi(-)pi(0) are studied with the psi(3686) data samples collected with the Beijing Spectrometer ( BESIII). For the first time, the branching fractions of chi(c2) -&gt; K*(K) over bar,chi(c2) -&gt; a(2)(+/-)(1320)pi(-/+)/a(2)(0)(1320)pi(0), and chi(c2) -&gt; rho(770)(+/-)pi(-/+) are measured. Here, K*(K) over bar denotes both K*K-+/-(-/+) and its isospin-conjugated process K*(0)(K) over bar (0) + c: c:, and K* denotes the resonances K*(892), K*(2)(1430), and K*(3)(1780). The observations indicate a strong violation of the helicity selection rule in chi(c2) decays into vector and pseudoscalar meson pairs. The measured branching fractions of chi(c2) -&gt; K*(892)(K) over bar are more than ten times larger than the upper limit of chi(c2) -&gt; rho(770)(+/-)pi(-/+), which is so far the first direct observation of a significant U-spin symmetry breaking effect in charmonium decays.</p>
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25.
  • Ablikim, M., et al. (författare)
  • Search for the radiative leptonic decay D+ -&gt; gamma e (+) nu(e)
  • 2017
  • Ingår i: Physical Review D : covering particles, fields, gravitation, and cosmology. - American Physical Society. - 2470-0010 .- 2470-0029. ; 95:7
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Using an electron-positron collision data sample of 2.93 fb(-1) collected at a center-of-mass energy of root s = 3.773 GeV with the BESIII detector, we present the first search for the radiative leptonic decay D+ -&gt; gamma e(+)nu(e). The analysis is performed with a double-tag method. We do not observe a significant D+ -&gt; gamma e(+)nu(e) signal, and obtain an upper limit on the branching fraction of D+ -&gt; gamma e(+)nu(e) decay with the energy of radiative photon larger than 10 MeV of 3.0 x 10(-5) at the 90% confidence level.</p>
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26.
  • Ablikim, M., et al. (författare)
  • Search for the rare decay <em>D+ → D<sup>0</sup>e+ν<sub>e</sub></em>
  • 2017
  • Ingår i: BESIII.
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Using a data set with an integrated luminosity of 2.93 fb(-1) collected at root s = 3.773 GeV with the BESIII detector operating at the BEPCII storage rings, we search for the rare decay D+ -&gt; D(0)e(+)nu(e). No signal events are observed. We set the upper limit on the branching fraction for D+ -&gt; D(0)e(+)nu(e) to be 1.0 x 10(-4) at the 90% confidence level.</p>
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27.
  • Ablikim, M., et al. (författare)
  • Dark photon search in the mass range between 1.5 and 3.4 GeV/c
  • 2017
  • Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 774, s. 252-257
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Using a data set of 2.93 fb taken at a center-of-mass energy root s = 3.773 GeV with the BESIII detector at the BEPCII collider, we perform a search for an extra U(1) gauge boson, also denoted as a dark photon. We examine the initial state radiation reactions e(+)e(-) -&gt; e(+)e(-) gamma(ISR) and e(+)e(-) -&gt; mu(+)mu(-) gamma(ISR) for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. We observe no obvious enhancement in the mass range between 1.5 and 3.4 GeV/c(2) and set a 90% confidence level upper limit on the mixing strength of the dark photon and the Standard Model photon. We obtain a competitive limit in the tested mass range.</p>
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28.
  • Ablikim, M., et al. (författare)
  • Determination of the number of J/psi events with inclusive J/psi decays
  • 2017
  • Ingår i: Chinese Physics C, High Energy Physics & Nuclear Physics. - 1674-1137 .- 0899-9996. ; 41:1
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>A measurement of the number of J/psi events collected with the BESIII detector in 2009 and 2012 is performed using inclusive decays of the J/psi. The number of J/psi events taken in 2009 is recalculated to be (223.7 +/- 1.4) x 10(6), which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESIII software. The number of J/psi events taken in 2012 is determined to be (1086.9 +/- 6.0) x 10(6). In total, the number of J/psi events collected with the BESIII detector is measured to be (1310.6 +/- 7.0) x 10(6), where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.</p>
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29.
  • Wei, Xiao-Ping, et al. (författare)
  • Investigations on electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl
  • 2017
  • Ingår i: Journal of Solid State Chemistry. - ACADEMIC PRESS INC ELSEVIER SCIENCE. - 0022-4596 .- 1095-726X. ; 247, s. 97-104
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Using full-potential local-orbital minimum-basis along with spin-polarized relativistic Korringa-Kohn-Rostoker methods, we study the electronic, Fermi surface, Curie temperature and optical properties of Zr2CoAl alloy. The alloy with Li2AgSb and Cu2MnAl structures are compared in terms of magnetic properties, and the electronic structures in two structures are also discussed. According to the calculated electronic states, it finds that the Zr2CoAl with Li2AgSb structure is half-metallic ferromagnet with an integral magnetic moment of 2.00 mu(beta), meanwhile we also notice the d-d and p-d hybridizations are responsible for the formation of minority-spin gap, furthermore, the fat-bands are applied to discuss the mixture between d and p electrons in the vicinity of the Fermi level. The Fermi surfaces related to the valence bands are constructed, and it is found that the spin-up valence bands 26, 27 and 28 across the Fermi energy dominate the nature of electrons. By mapping the system onto a Heisenberg Hamiltonian, we obtain the exchange coupling parameters, and observe that the Zr(A)-Co(C) and Zr(A)-Zr(B) interactions provide a major contribution for exchange interactions. Based on the calculated exchange coupling parameters, the Curie temperature is estimated to be 287.86 K at equilibrium, and also the dependence of Curie temperature on lattice constant related to the tunable Curie temperature in Zr2CoAl alloy is studied. Finally, we report the optical properties of Zr2CoAl alloy, and present the photon energy dependence of the absorption, the optical conductivity and the loss function.</p>
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30.
  • Fu, Yu-dong, et al. (författare)
  • The role of group III, IV elements in Nb(4)AC(3) MAX phases (A = Al, Si, Ga, Ge) and the unusual anisotropic behavior of the electronic and optical properties
  • 2017
  • Ingår i: Physical Chemistry, Chemical Physics - PCCP. - Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 19:23, s. 15471-15483
  • Tidskriftsartikel (refereegranskat)abstract
    • <p>Niobium based Nb4AlC3, Nb4SiC3, Nb4GeC3 and Nb4GaC3 were investigated by means of density functional theory. Together with the known Nb4AlC3, the role of group III, IV elements in various properties of Nb(4)AC(3) (A = Al, Si, Ga, Ge) was systematically investigated, and particularly the bulk moduli, shear moduli, and Young's moduli helped us to approach the ductility. All the studied compounds were found to be mechanically stable, and they also exhibit the metallic nature that results from the Nb-4d states being dominant at the Fermi level. The typical 4d-2p hybridization leads to strong Nb-C covalent bonding and a relatively weaker 4d-3p (4p) hybridization between Nb and A is identified. The latter does perturb the performance of materials. By varying A elements in Nb(4)AC(3), the position and the width of the p states as well as hybridizations are altered, which determine the covalency and the ionicity of the chemical bonds. A high density of states at the Fermi level and the nesting effects in the Fermi surface are identified in Nb4SiC3 and linked to its unusual anisotropic behavior. Furthermore, Nb4GeC3 is predicted to be a very promising candidate solar heating barrier material. Overall, the present work gives insights into the role of A elements in the electronic structure and the physical properties of Nb(4)AC(3) compounds. The tendencies and rules established here will help in the designing of functional ceramic materials with desirable properties.</p>
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