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The discovery of Ξcc++has inspired new interest in studying doubly heavy baryons.In this study,the weak decays of a doubly charmed baryon Bccto a light baryon B and a charm meson D*(either a pseudoscalar or a vector one)are calculated.Following our previous work,we calculate the short distance contributions under the factorization hypothesis,whereas the long distance contributions are modeled as the final state interactions,which are calculated with the one particle exchange model.We find that the Bcc→BD*decays'branching ratios are obviously larger,as they receive contributions of more polarization states.Among the decays that we investigate,the following have the largest branching fractions:BR(Ξcc++→∑+D*+)∈[0.46%,3.33%]estimated with τΞcc++=256 fs;BR(Ξcc+→AD*+)∈[0.38%,2.63%]and BR(Ξcc+→∑0D*+)∈[0.45%,3.16%]with τΞcc++=45 fs;and BR(Ωcc+→Ξ0D+)∈[0.27%,1.03%),BR(Ωcc+→∑0D*+)∈[0.07%,0.44%],and BR(Ωcc+→∑0D*+)∈[0.06%,0.45%] with τ_(Ωcc)+=75 fs.By comparing the decay widths of pure color commensurate channels with those of pure bow-tie ones we find that the bow-tie mechanism plays an important role in charm decays. 相似文献
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(Sr,Ba)SiO3:Eu3+是以SrCO3、BaCO3、H2SiO3、Li2CO3、Eu2(C2O4)3为原料,经高温烧结而成。合成发光材料过程中,用正交试验法进行实验条件的探索。得到了发光材料的最佳组成为:(Sr0.8Ba0.2)0.95Eu0.025Li0.025SiO3或Si0.95Eu0.025Li0.025SiO3。最佳实验条件为:灼烧温度1150℃,灼烧时间3小时。通过X-射线粉末衍射谱、激光荧光光谱、发光光谱和激发光谱研究了发光材料的结构和发光特性。 相似文献
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(Sr,Ba)SiO_3:Eu~(3+)是以SrCO_3、BaCO_3、H_2SiO_3、Li_2CO_3、Eu_2(C_2O_4)_3为原料,经高温烧结而成。合成发光材料过程中,用正交试验法进行实验条件的探索。得到了发光材料的最佳组成为:(Sr_(0.8)Ba_(0.2))_(0.95)Eu_(0.025)Li_(0.025)SiO_3或Si_(0.95)Eu_(0.025)Li_(0.025)SiO_3。最佳实验条件为:灼烧温度1150℃,灼烧时间3小时。通过X-射线粉末衍射谱、激光荧光光谱、发光光谱和激发光谱研究了发光材料的结构和发光特性。 相似文献
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Grant等人[1]在研究由水解K*CN制取标记甲酸盐的过程中发现,以杂质形式存在于K*CN中的碳酸盐与甲酸盐之间进行14C的交换,并提出了可能的反应历程.我们在工作中发现碳酸钠和乙酸钠、丙酸钠、硬脂酸钠之间不发生14C交换反应,并验证了甲酸钠和碳酸氢钠之间的交换反应。我们还探讨了交换反应历程,活化能和反应速度常数。 相似文献
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