Utilizing a data sample corresponding to an integrated luminosity of 2.93 fb-1 recorded by the BESIII detector at a center-of-mass energy of 3.773 GeV, we present an analysis of the decays ...D0→π-π0e+ve and D+→π-π+e+ve . Using a partial wave analysis, the π+π- S-wave contribution to D+→π-π+e+ve is observed for the first time besides the dominant P-wave contribution; the statistical significance is greater than 10σ with its measured fraction (25.7 ± 1.6 ± 1.1)%. We measure the branching fractions $\mathcal{B(D^0→p^-e^+v_e)}$ = (1.445 ± 0.058 ± 0.039) × 10-3, $\mathcal{B(D^+→p^0e^+v_e)}$ = (1.860 ± 0.070 ± 0.061) × 10-3 and $\mathcal{B(D^+→f_0(500)e^+v_e)}$, f0(500)→ π+π -) = (6.30 ± 0.43 ± 0.32) × 10-4. An upper limit of $\mathcal{B(D^+→f_0(980)e^+v_e)}$, f0(980)→π+π -) < 2.8 × 10-5 is set at the 90% confidence level. We also obtain the hadronic form factor ratios of D→ρe+ve at q2 = 0 assuming the single-pole dominance parameterization: rv = {V(0)/A1(0)} = 1.695 ± 0.083 ± 0.051, r2 = {A2(0)\A1(0)} = 0.845 ± 0.056 ± 0.039.
Display omitted
Anion exchange membranes (AEMs) are a crucial constituent for alkaline fuel cells. As the core component of fuel cells, the low performance AEMs restrict the development and ...application of the fuel cells. Herein, the trade-off between the OH– conductivity and dimensional stability was solved by constructing AEMs with adequate OH– conductivity and satisfactory alkali resistance using Tröger’s base (TB) poly (crown ether)s (PCEs) as the main chain, the embedded quaternary ammonium (QA) and Na+-functionalized crown ether units as the cationic group. Crown ether is an electron donator, and can capture Na+ to form Na+-functionalized crown ether units to conveniently transfer OH– and significantly promote the alkaline stability of the AEMs. The influence of the Na+-functionalized crown ether units on the performance of AEMs was studied in detail. The PCEs based AEMs show an obvious hydrophobic-hydrophilic microphase separation. These features make them ideal platforms for the OH– conduction applications. As expected, the as-prepared PCEs-QA-100% (100% is the degree of cross-linking) AEM with an ionic exchange capacity (IEC) of 2.07 meq g−1 has a high OH– conductivity of 159 mS cm−1 at 80 °C. Furthermore, the membrane electrode assemblies fabricated using the PCEs-QA-100% AEM possess a maximum power density of 291 mW cm−2 under the current density of 500 mA cm−2.
Using a $3.19\text{ }\text{ }{\mathrm{fb}}^{{-}1}$ data sample collected at an ${e}^{+}{e}^{{-}}$ center-of-mass energy of ${E}_{\mathrm{cm}}=4.178\text{ }\text{ }\mathrm{GeV}$ with the BESIII ...detector, we measure the branching fraction of the leptonic decay ${D}_{s}^{+}{\rightarrow}{{\mu}}^{+}{{\nu}}_{{\mu}}$ to be ${\mathcal{B}}_{{D}_{s}^{+}{\rightarrow}{{\mu}}^{+}{{\nu}}_{{\mu}}}=(5.49\pm{}0.1{6}_{\text{stat}}\pm{}0.1{5}_{\text{syst}})\times{}{10}^{{-}3}$. Combining our branching fraction with the masses of the ${D}_{s}^{+}$ and ${{\mu}}^{+}$ and the lifetime of the ${D}_{s}^{+}$, we determine ${f}_{{D}_{s}^{+}}|{V}_{cs}|=246.2\pm{}3.{6}_{\text{stat}}\pm{}3.{5}_{\text{syst}}\text{ }\text{ }\mathrm{MeV}$. Using the $c{\rightarrow}s$ quark mixing matrix element $|{V}_{cs}|$ determined from a global standard model fit, we evaluate the ${D}_{s}^{+}$ decay constant ${f}_{{D}_{s}^{+}}=252.9\pm{}3.{7}_{\text{stat}}\pm{}3.{6}_{\text{syst}}\text{ }\text{ }\mathrm{MeV}$. Alternatively, using the value of ${f}_{{D}_{s}^{+}}$ calculated by lattice quantum chromodynamics, we find $|{V}_{cs}|=0.985\pm{}0.01{4}_{\text{stat}}\pm{}0.01{4}_{\text{syst}}$. These values of ${\mathcal{B}}_{{D}_{s}^{+}{\rightarrow}{{\mu}}^{+}{{\nu}}_{{\mu}}}$, ${f}_{{D}_{s}^{+}}|{V}_{cs}|$, ${f}_{{D}_{s}^{+}}$ and $|{V}_{cs}|$ are each the most precise results to date.
We observe the process ψ(3686)→p$\overline{p}$η' for the first time, with a statistical significance higher than 10σ, and measure the branching fraction of J/ψ→p$\overline{p}$η' with an improved ...accuracy compared to earlier studies. The measurements are based on 4.48 × 108 ψ(3686) and 1.31 × 109 J/ψ events collected by the BESIII detector operating at the BEPCII. The branching fractions are determined to be $\mathcal{B(ψ(3686)→p\overline{p}η')}$ = (1.10 ± 0.10 ± 0.08)×10-5 and $\mathcal{B(J/ψ →p\overline{p}η')}$ = (1.26 ± 0.02 ± 0.07) ×10-4, where the first uncertainties are statistical and the second ones systematic. Also, the η- η' mixing angle is determined to be -24° ± 11° based on ψ(3686)→p$\overline{p}$η', and -24° ± 9° based on J/ψ→p$\overline{p}$η', respectively.
First observations of h c → hadrons Achasov, M. N.; Ahmed, S.; Amoroso, A. ...
Physical review. D,
04/2019, Letnik:
99, Številka:
7
Journal Article
Recenzirano
Based on (4.48 ± 0.03) ×108 ψ(3686) events, collected with the BESIII detector at the BEPCII storage ring, five hc hadronic decays are searched for via the process ψ(3686) → π0hc. Three of them, hc → ...pp¯π+π–, π+π–π0, and 2(π+π–)π0, are observed for the first time with significances of 7.4σ, 4.6σ, and 9.1σ, and their branching fractions are determined to be (2.89 ± 0.32 ± 0.55) × 10–3, (1.60 ± 0.40 ± 0.32) × 10–3, and (7.44 ± 0.94 ± 1.52) × 10–3, respectively, where the first uncertainties are statistical and the second systematic. No significant signal is observed for the other two decay modes, and the corresponding upper limits of the branching fractions are determined to be B(hc → 3(π+π–)π0) < 8.7 × 10–3 and B(hc → K+K–π+π–) < 5.8 × 10–4 at the 90% confidence level.
Observation of η ′ → ω e + e Achasov, M. N.; Amoroso, A.; An, F. F. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
09/2015, Letnik:
92, Številka:
5
Journal Article
Study of the decay D0 → K ¯ 0π-e+νe An, F. F.; Ferroli, R. Baldini; Berger, N. ...
Physical review. D,
01/2019, Letnik:
99, Številka:
1
Journal Article
The effects of Ru on microstructure and creep properties of the two alloys were investigated in detail. According to the creep curves of the two alloys at 1140 °C/137 MPa, the creep rupture life was ...significantly improved with the increase of Ru and the mechanism of each stage during the creep deformation was different. Thus, the evolution of the γ' phase, the dislocation configuration, and the effect of Ru on solution strengthening were discussed. The γ/γ' lattice misfit of the initial microstructure presented increasingly negative as the content of Ru increased, which resulted in smaller and more regular γ' particles in the initial state. Meanwhile, more consistent and denser dislocation networks on the γ/γ' interface during creep deformation were examined. Hence, the addition of Ru decreased the minimum creep rate and prolonged the secondary creep stage. Moreover, the so-called “reverse partitioning” behavior and enhancement of γ matrix strength appeared with the increase of Ru. When the alloy contained 2.5 wt% Ru, the rapidly increasing in creep strain rate induced by the topological inversion appeared. When the alloy included 3.5 wt% Ru, the needle-like and rod-like topologically close-packed (TCP) phases were observed occasionally. The stress and the supersaturation of refractory elements resulted in the precipitation of the TCP phase. The dramatic increase of the creep strain rate was principally related to the propagation of micro-cracks around the casting and creep voids in the necked regions.
Decays $\mathcal{x_{cj}}$ (J = 0, 1, 2)→ωφ are studied using (448.1 ± 2.9) × 106ψ(3686) events collected with the BESIII detector in 2009 and 2012. Futhermore, In addition to the previously ...established $\mathcal{x_{c0}}$→ωΦ, the first observation of $\mathcal{x_{c1}}$→ωΦ is reported in this paper. The measured product branching fractions are $\mathcal{B(ψ(3686)→γχ_{c0}) × B(χ_{c0}→ωΦ)}$ = (13.83 ± 0.70 ± 1.01) × 10-6 and $\mathcal{B(ψ(3686)→γχ_{c1}) × B(χ_{c1}→ωΦ)}$ = (2.67 ± 0.31 ± 0.27) × 10-6, and the absolute branching fractions are $\mathcal{B(x_{c0}→ωΦ)}$ = (13.84 ± 0.70 ± 1.08) × 10-5 and $\mathcal{B(x_{c1}→ωΦ)}$ = (2.80 ± 0.32 ± 0.30) × 10-5. Furthermore, we find a strong evidence for $\mathcal{x_{c2}}$→ωΦ with a statistical significance of 4.8σ, and the corresponding product and absolute branching fractions are measured to be$\mathcal{B(ψ(3686)→γχ_{c2})×B(χ_{c2}→ωΦ)}$ = (0.91 ± 0.23 ± 0.12) × 10-6 and $\mathcal{B(x_{c2}→ωΦ)}$ = (1.00 ± 0.25 ± 0.14) × 10-5. Here, the first errors are statistical and the second ones systematic.
PDF
