分类: 物理学 >> 核物理学 提交时间: 2016-08-29
摘要: Based on a sample of 1.31×109 J/ψ events collected with the BESIII detector, an amplitude analysis of the isospin violating decays η′→π+π−π0 and η′→π0π0π0 is performed. Significant P-wave contribution from η′→ρ±π∓ is observed for the first time in η′→π+π−π0. The branching fraction is determined to be B(η′→ρ±π∓)=(7.44±0.60±1.26±1.84)×10−4, where the first uncertainty is statistical, the second systematic and the third model dependent. In addition to the non-resonant S-wave component, a contribution from the σ meson is also essential. The branching fractions of the S-wave components are determined as B(η′→π+π−π0)S=(37.63±0.77±2.22±4.48)×10−4 and B(η′→π0π0π0)=(35.22±0.82±2.60)×10−4, respectively. The latter one is consistent with previous BESIII measurements.
分类: 物理学 >> 核物理学 提交时间: 2016-08-25
摘要: The process e+e−→η′J/ψ is observed for the first time with a statistical significance of 8.6σ at center-of-mass energy s√=4.226 GeV and 7.3σ at s√=4.258 GeV using data samples collected with the BESIII detector. The Born cross sections are measured to be (3.7±0.7±0.3) and (3.9±0.8±0.3) pb at s√=4.226 and 4.258 GeV, respectively, where the first errors are statistical and the second systematic. Upper limits at the 90% confidence level of the Born cross sections are also reported at other 12 energy points
分类: 物理学 >> 核物理学 提交时间: 2016-08-25
摘要: By analyzing 2.93 fb−1 data collected at the center-of-mass energy s√=3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D+→K¯0e+νe to be B(D+→K¯0e+νe)=(8.59±0.14±0.21)% using K¯0→K0S→π0π0, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties.
分类: 物理学 >> 核物理学 提交时间: 2016-08-25
摘要: By analyzing 2.93 fb−1 of data collected at s√=3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D+→K¯0μ+νμ)=(8.72±0.07stat.±0.18sys.)%, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D0→K−μ+νμ), B(D+→K¯0e+νe), and the lifetimes of the D0 and D+ mesons with the value of B(D+→K¯0μ+νμ) measured in this work, we determine the following ratios of partial widths: Γ(D0→K−μ+νμ)/Γ(D+→K¯0μ+νμ)=0.963±0.044 and Γ(D+→K¯0μ+νμ)/Γ(D+→K¯0e+νe)=0.988±0.033.
分类: 物理学 >> 核物理学 提交时间: 2016-08-24
摘要: Using a data set of 2.93 fb−1 taken at a center-of-mass energy of s√ = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process e+e−→J/ψγ→μ+μ−γ and determine the product of the branching fraction and the electronic width Bμμ⋅Γee=(333.4±2.5stat±4.4sys)~eV. Using the earlier-published BESIII result for Bμμ = (5.973 ± 0.007stat ± 0.037sys)\%, we derive the J/ψ electronic width Γee~= (5.58 ± 0.05stat ± 0.08sys) keV.
分类: 物理学 >> 核物理学 提交时间: 2016-08-19
摘要: We present the first search for the rare decay of η′ into K±π∓ in J/ψ→ϕη′, using a sample of 1.3×109 J/ψ events collected with the BESIII detector. No significant signal is observed, and the upper limit at the 90\% confidence level for the ratio B(η′→K±π∓)B(η′→γπ+π−) is determined to be 1.3×10−4. In addition, we report the measurement of the branching fraction of J/ψ→ϕη′ to be (5.10±0.03(stat.)±0.32(syst.))×10−4, which agrees with previous results from BESII.
分类: 物理学 >> 核物理学 提交时间: 2016-08-19
摘要: We study the decays of the charmonium resonances J/ψ and ψ(3686) to the final states Ξ−Ξ¯+, Σ(1385)∓Σ¯(1385)± based on a single baryon tag method using data samples of (223.7±1.4)×106 J/ψ and (106.4±0.9)×106 ψ(3686) events collected with the BESIII detector at the BEPCII collider. The decay ψ(3686)→Σ(1385)∓Σ¯(1385)± is observed for the first time, and the measurements of the other processes, including the branching fractions and angular distributions, are in good agreement with and much more precise than the previously published results. Additionally, the ratios B(ψ(3686)→Ξ−Ξ¯+)B(J/ψ→Ξ−Ξ¯+), B(ψ(3686)→Σ(1385)−Σ¯(1385)+)B(J/ψ→Σ(1385)−Σ¯(1385)+) and B(ψ(3686)→Σ(1385)+Σ¯(1385)−)B(J/ψ→Σ(1385)+Σ¯(1385)−) are determined.
分类: 物理学 >> 核物理学 提交时间: 2016-08-17
摘要: Based on a sample of (1310.6±10.5)×106 J/ψ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay J/ψ→γϕϕ is performed in order to study the intermediate states. Results of the partial wave analysis show that the structures are predominantly 0−+ states. The existence of the η(2225) is confirmed, and its resonance parameters are measured. Two additional pseudoscalar states, the η(2100) with a mass of 2050+30−24+75−26~MeV/c2 and a width of 250+36−30+181−164~MeV/c2 and the X(2500) with a mass of 2470+15−19+101−23~MeV/c2 and a width of 230+64−35+56−33~MeV/c2, are observed. In addition to these three pseudoscalar states, the scalar state f0(2100), and three tensor states, the f2(2010), f2(2300) and f2(2340), are observed in the process J/ψ→γϕϕ. The product branching fractions B(J/ψ→γX)×B(X→ϕϕ) are reported.