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本文研究了用动量为68亿电子伏/c和80亿电子伏/c的刀π~-介子产生Ξ~-超子,得到了π~-介子的动量为68和80亿电子伏/c的Ξ~-产生的截面(当68亿电子伏/c时σ=3.6_(-2.1)~( 2.5)μδ/N,当80亿电子伏/c时σ=10.6_(-3.2)~( 4.4)μδ/N),Ξ~-的质量(M_Ξ~-=1317.0±2.2兆电子伏)和Ξ的寿命τ_0=3.5_(-1.2)~( 3.4)×10~(-10)秒。 相似文献
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过去一年里,运行在日本高能加速器研究机构的Belle实验在重子研究,尤其是在超子和粲重子研究上取得了一系列重要实验进展,包括发现了两个超子Ξ(16 20)和Ω(20 12)、一个粲重子Ξc(29 30)等新的重子,并首次测量了粲重子Ξc衰变的绝对分支比等,为完善重子谱和深入理解强相互作用性质提供了关键的实验数据。 相似文献
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Search for the doubly heavy baryons Ω_(bc)~0 and Ξ_(bc)~0 decaying to Λ_c~+π~- and Ξ_c~+π~- 下载免费PDF全文
《中国物理C(英文版)》2021,(9)
The first search for the doubly heavy Ω_(bc)~0 baryon and a search for the Ξ_(bc)~0 baryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.2 fb~(-1).The baryons are reconstructed via their decays to ∧_c~+π~-andΞ_c~+π~-.No significant excess is found for invariant masses between 6700 and 7300 MeV/c2,in a rapidity range from2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c.Upper limits are set on the ratio of the Ω_(bc)~0 andΞ_(bc)~0 production cross-section times the branching fraction to ∧_c~+π~-(Ξ_c~+π~-) relative to that of the ∧_b~0(Ξ_b~0) baryon,for different lifetime hypotheses,at 95% confidence level.The upper limits range from 0.5×10~(-4) to 2.5×10~(-4) for theΩ_(bc)~0→∧_c~+π~-(Ξ_(bc)~0→∧_c~+π~-) decay,and from 1.4×10~(-3) to 6.9×10~(-3) for the Ω_(bc)~0→Ξ_c~+π~-(Ξ_(bc)~0→Ξ_c~+π~-) decay,depending on the considered mass and lifetime of the Ω_(bc)~0(Ξ_(bc)~0) baryon. 相似文献
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J/(?)粒子谱表明这些粒子由一对费米子组成.这个新的组成成分具有粲数c,它也出现于其它强子中,构成粲介子和粲重子.最近实验找到的D(1.865)、D~*(2.005)和重子(2.260),可能都是粲粒子.本文用两个模型来研究粲粒子质量谱的规律性. 方案A[SU(4)理论] SU(4)质量关系的讨论已经很多,大多假定了质量算符取~αΤ_8+βΤ_(15)形式.但由于粲自由度的破缺很大,不能看作线性,这样做结果往往和实验符合不佳.我们仍采用资料[10]的分析方法,从层子二体作用的普遍概念出发进行研究.将层子u,d记为O;s记为●;c记为△,它们的质量(包括动能)分别为n_o、λ_o和c_o,则各种二体作用可图示如下(介子中相应量用带撇文字表示): 相似文献
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基于SU(3)对称性研究了χc0的遍举多体衰变χc0→B(-B)MM(B:重子,M:介子),通过同位旋耦合常数构造了χc0→B(-B)→B(-B)MM衰变的跃迁振幅.基于这些跃迁振幅,发现N*共振态对χc0→B(-B)ππ的贡献相对较大,这个衰变道可以在实验上用来研究N*共振态. 相似文献
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《物理》2017,(4)
利用北京谱仪BESIII实验采集的约9 fb~(-1)数据样本,BESIII测量了e~+e~-→π~+π~- J/ψ过程的产生截面,并对在该过程中观测到的Y(4260)粒子的质量和宽度做了目前世界上最精确的测量。BESIII的测量给出Y(4260)粒子的质量在4.22 GeV/c~2左右,比之前的测量偏低;宽度约44 MeV,比之前的测量窄很多。相比之前的实验,BESIII对Y(4260)粒子参数的精确测量给解释该粒子的理论模型提供了更强的约束。另外,BESIII实验在4.32 GeV/c~2附近还观测到一个新粒子信号,信号显著性为7.6σ。新粒子的质量和宽度和之前观测到的Y(4360)粒子的质量和宽度在误差范围内吻合,有可能是同一个粒子。 相似文献
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The doubly charmed baryon Ξ_(cc)~(++) was recently observed by LHCb via the decay processes ofΞ_(cc)~(++)→∧_c~+K~-π~+π~+ and Ξ_c~+π~+. These discovery channels were successfully predicted in a framework in which the short-distance contributions are calculated under the factorization hypothesis and the long-distance contributions are estimated using the rescattering mechanism for the final-state-interaction effects.In this paper,we illustrate the above framework in detail by systematic studies on the two-body baryonic decays B_(cc)→B_cP involving the doubly charmed baryons B_(cc)=(Ξ_(cc)~(++),Ξ_(cc)~+,Ω_(cc)~+),the singly charmed baryons B_c=(B_3,B_6) and the light pseudoscalar mesons P=(π,K,η_(1,8)). 相似文献
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用一个简化模型概括的低激发态重子主要衰变分支比和我们在文献[2]中给出的基本关系,得出L=1激发态重子对∑+(1385),∑+,Ξ0(1530)和Ξ0的衰变贡献,进而用γ共振能量下的实验值R1=(1530)/Ξ,R2=∑(1385)/∑和R3=∧(1520)/∑(1385)作输入,估算了L=1的各激发态重子的产生比例. 相似文献
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Based on a systematic investigation of J/ψ(ψ) → VP,where V and P stand for light vector and pseudoscalar mesons,we identify the role played by the electromagnetic(EM) transitions and intermediate meson loop transitions,which are essential ingredients for understanding the J/ψ and ψ couplings to VP.We show that on the one hand,the EM transitions have relatively larger interferences in ψ→ρπ and K*K+c.c.as explicitly shown by vector meson dominance(VMD).On the other hand,the strong decay of ψ receives relatively larger destructive interferences from the intermediate meson loop transitions.By identifying these mechanisms in an overall study of J/ψ(ψ)→VP,we provide a coherent understanding of the so-called "ρπ puzzle". 相似文献