Radioactivities of 189W are produced through an 192Os(n, α)189W reaction.Gamma ray spectroscopy from chemically separated tungsten sources using HPGe detector has revealed the presence of 22 gamma rays assigned to th...Radioactivities of 189W are produced through an 192Os(n, α)189W reaction.Gamma ray spectroscopy from chemically separated tungsten sources using HPGe detector has revealed the presence of 22 gamma rays assigned to the decay of 189W. Of them, 18 gamma rays are new ones unreported until now.展开更多
We study radiative decays of T to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet b^-b operators into consideration. The cut for quark jet energy and cut for the angle between ...We study radiative decays of T to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet b^-b operators into consideration. The cut for quark jet energy and cut for the angle between two quark jets are introduced. The sensitivity to the soft and collinear singularities in the loop integrals are greatly reduced by these cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about 36°, the branching ratio for γ→ rq^- is found to be 8.2 × 10^-4 from color singlet contributions. The color octet contributions could be much larger than that of color singlet, depending on the estimate of the color octet matrix elements. This process may provide a new test for the color octet mechanism in nonrelativistic QCD.展开更多
Weak radiative hyperon decays,important to test the strong interaction and relevant in searches for beyond the standard model physics,have remained puzzling both experimentally and theoretically for a long time.The re...Weak radiative hyperon decays,important to test the strong interaction and relevant in searches for beyond the standard model physics,have remained puzzling both experimentally and theoretically for a long time.The recently updated branching fraction and first measurement of the asymmetry parameter of Λ→nγ by the BESIII Collaboration further exacerbate the issue,as none of the existing predictions can describe the data.We show in this work that the covariant baryon chiral perturbation theory,with constraints from the latest measurements of hyperon non-leptonic decays,can well describe the BESIII data.The predicted branching fraction and asymmetry parameter for Ξ→Σγ are also in agreement with the experimental data.We note that a more precise measurement of the asymmetry parameter,which is strongly constrained by chiral symmetry and related with that of Σ→pγ,is crucial to test Hara’s theorem.We further predict the branching fraction and asymmetry parameter of Σ~0→nγ,whose future measurement can serve as a highly nontrivial check on our understanding of weak radiative hyperon decays and on the covariant baryon chiral perturbation theory.展开更多
文摘Radioactivities of 189W are produced through an 192Os(n, α)189W reaction.Gamma ray spectroscopy from chemically separated tungsten sources using HPGe detector has revealed the presence of 22 gamma rays assigned to the decay of 189W. Of them, 18 gamma rays are new ones unreported until now.
基金The project supported in part by National Natural Science Foundation of China under Grant No. 10421503 and the Key Project of the Ministry of Education under Grant No. 305001, and the Research Found of Doctorial Programs of Higher Education of China. We thank E. Berger for bringing their earlier work on inelastic photoproduction of T （Ref. [12]） to our attention. We would also like to thank Ce Meng for valuable discussions.
文摘We study radiative decays of T to light quark jets in nonrelativistic QCD by taking both the color singlet and color octet b^-b operators into consideration. The cut for quark jet energy and cut for the angle between two quark jets are introduced. The sensitivity to the soft and collinear singularities in the loop integrals are greatly reduced by these cuts. With the jet energy cut of about 1 GeV, and the jet angle cut of about 36°, the branching ratio for γ→ rq^- is found to be 8.2 × 10^-4 from color singlet contributions. The color octet contributions could be much larger than that of color singlet, depending on the estimate of the color octet matrix elements. This process may provide a new test for the color octet mechanism in nonrelativistic QCD.
基金supported in part by the National Natural Science Foundation of China (11735003, 11975041, and11961141004)support from the National Natural Science Foundation of China (12147145)+2 种基金support from the National Natural Science Foundation of China (12105006)Project funded by China Postdoctoral Science Foundation (2021M700343)China Postdoctoral Science Foundation (2021M690008)
文摘Weak radiative hyperon decays,important to test the strong interaction and relevant in searches for beyond the standard model physics,have remained puzzling both experimentally and theoretically for a long time.The recently updated branching fraction and first measurement of the asymmetry parameter of Λ→nγ by the BESIII Collaboration further exacerbate the issue,as none of the existing predictions can describe the data.We show in this work that the covariant baryon chiral perturbation theory,with constraints from the latest measurements of hyperon non-leptonic decays,can well describe the BESIII data.The predicted branching fraction and asymmetry parameter for Ξ→Σγ are also in agreement with the experimental data.We note that a more precise measurement of the asymmetry parameter,which is strongly constrained by chiral symmetry and related with that of Σ→pγ,is crucial to test Hara’s theorem.We further predict the branching fraction and asymmetry parameter of Σ~0→nγ,whose future measurement can serve as a highly nontrivial check on our understanding of weak radiative hyperon decays and on the covariant baryon chiral perturbation theory.
