Recent results on hadronic ϒ(1S/2S) decays at Belle

详细信息    查看全文

• 作者：S.D. Yang^a ; ^{shaodanyang@pku.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; on behalf of Belle Collaboration
• 关键词：ϒ(1S/2S)ϒ(1S/2S) decays ; charmonium-(like) productions ; light hadrons ; hadronic transitions
• 刊名：Nuclear and Particle Physics Proceedings
• 出版年：2016
• 出版时间：January-March 2016
• 年：2016
• 卷：270-272
• 期：Complete
• 页码：118-122
• 全文大小：1558 K

文摘

Using the data samples of 102×10⁶ϒ(1S)$102\times {10}^6\mathrm{\Upsilon }(1S)$ and 158×10⁶ϒ(2S)$158\times {10}^6\mathrm{\Upsilon }(2S)$ events collected at Belle, several studies on ϒ(1S/2S)$\mathrm{\Upsilon }(1S/2S)$ decays have been performed recently. Charge-parity-even charmonium(-like) states, such as χ_c0,1,2${\chi }_{c0,1,2}$, η_c${\eta }_c$, X(3872), X(3915), Y(4140), and X  (4350) (only in ϒ(2S)$\mathrm{\Upsilon }(2S)$ data), are first searched in ϒ(1S/2S)$\mathrm{\Upsilon }(1S/2S)$ radiative decays, though there are no significant signals observed. Among double-charmonium final states from ϒ(1S/2S)$\mathrm{\Upsilon }(1S/2S)$ exclusive decays, the evidence for ϒ(1S)→J/ψχ_c1$\mathrm{\Upsilon }(1S)\to J/\psi {\chi }_{c1}$ was found first with a signal significance of 4.6σ, and the branching fraction was measured to be (3.90 ± 1.21(stat.) ± 0.23(syst.)) × 10^-6. Some exclusive light hadronic decays are also searched for the first time, including the intermediate vector-tensor, axial-vector-pseudoscaler, and vector-pseudoscaler processes. Signals are observed in the ϒ(1S)→ϕK⁺K⁻$\mathrm{\Upsilon }(1S)\to \varphi K^{+}{K}^{-}$, ωπ⁺π⁻$\omega {\pi }^{+}{\pi }^{-}$, K^⁎(892)⁰K⁻π⁺$K^{⁎}{(892)}^0{K}^{-}{\pi }^{+}$, $K_S^0{K}^{+}{\pi }^{-}+c.c.$, π⁺π⁻π⁰π⁰${\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$, $K^{⁎}{(892)}^0{\bar{K}}_2^{⁎}{(1430)}^0$ and ϒ(2S)→ϕK⁺K⁻$\mathrm{\Upsilon }(2S)\to \varphi K^{+}{K}^{-}$, K^⁎(892)⁰K⁻π⁺$K^{⁎}{(892)}^0{K}^{-}{\pi }^{+}$, π⁺π⁻π⁰π⁰${\pi }^{+}{\pi }^{-}{\pi }^0{\pi }^0$ decay modes, and evidence is found for the modes of ϒ(1S)→π⁺π⁻π⁰$\mathrm{\Upsilon }(1S)\to {\pi }^{+}{\pi }^{-}{\pi }^0$, K₁(1400)⁺K⁻$K_1{(1400)}^{+}{K}^{-}$, $K^{⁎}{(892)}^0{\bar{K}}^0+c.c.$ and $\mathrm{\Upsilon }(2S)\to K_S^0{K}^{+}{\pi }^{-}+c.c.$, $K^{⁎}{(892)}^0{\bar{K}}_2^{⁎}{(1430)}^0$. In addition, the study of the hadronic transitions, ϒ(2S)→(η,π⁰)ϒ(1S)$\mathrm{\Upsilon }(2S)\to (\eta ,{\pi }^0)\mathrm{\Upsilon }(1S)$, is performed, and B(ϒ(2S)→ηϒ(1S))=(3.57±0.25(stat.)±0.21(syst.))×106−4$\mathcal{B}(\mathrm{\Upsilon }(2S)\to \eta \mathrm{\Upsilon }(1S))=(3.57\pm 0.25(\text{stat.})\pm 0.21(\text{syst.}))\times 106-4$ and B(ϒ(2S)→π⁰ϒ(1S))<4.1×10⁻⁵$\mathcal{B}(\mathrm{\Upsilon }(2S)\to {\pi }^0\mathrm{\Upsilon }(1S))<4.1\times {10}^{-5}$ (90%C.L.) are obtained.