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論文

Results of $$bar{K}NN$$ search via the $$(K^-, n)$$ reaction at J-PARC

山我 拓巳*; 橋本 直; 谷田 聖; 他66名*

JPS Conference Proceedings (Internet), 26, p.023008_1 - 023008_6, 2019/11

There is a long-standing argument of the existence of kaonic nucleus, which is a bound state of anti-kaon and nucleus. Theoretically, its existence is strongly supported, however its binding energy and width have not been established yet. It is strongly desired to have an experiment to investigate the simplest kaonic nucleus, so-called $$K^-pp$$ bound state. We performed an experiment to search for $$K^-pp$$ via the in-flight $$(K^-, n)$$ reaction at J-PARC. By studying $$Lambda p$$ invariant mass spectrum in the $$Lambda pn$$ final state and its dependence on momentum transfer of $$K^{-}N to bar{K}N$$, we observed a resonant state located below $$M_{K^{-}pp}$$. The mass and width of this resonant state are $$2324 pm 3(textit{stat}.)_{-3}^{+6}(textit{syst}.)$$ MeV/$$c^2$$, and $$115 pm 7(textit{stat}.)_{-20}^{+10}(textit{syst}.)$$ MeV, respectively, which can be naturally interpreted as a theoretically predicted $$K^-pp$$ bound state.

論文

First measurement of the CKM angle $$phi_3$$ with $$B^{pm}to D(K_{rm S}^0pi^+pi^-pi^0)K^{pm}$$ decays

Resmi, P. K.*; 谷田 聖; Belle Collaboration*; 他166名*

Journal of High Energy Physics, 2019(10), p.178_1 - 178_27, 2019/10

 被引用回数:0 パーセンタイル:100

We present the first model-independent measurement of the CKM unitarity triangle angle $$phi_3$$ using $$B^{pm}to D(K_{rm S}^0pi^+pi^-pi^0)K^{pm}$$ decays, where $$D$$ indicates either a $$D^{0}$$ or $$overline{D}^{0}$$ meson. Measurements of the strong-phase difference of the $$D to K_{rm S}^0pi^+pi^-pi^0$$ amplitude obtained from CLEO-c data are used as input. This analysis is based on the full Belle data set of $$772times 10^{6}$$ $$Boverline{B}$$ events collected at the $$Upsilon(4S)$$ resonance. We obtain $$phi_3 = (5.7~^{+10.2}_{-8.8} pm 3.5 pm 5.7)^{circ}$$ and the suppressed amplitude ratio $$r_{B} = 0.323 pm 0.147 pm 0.023 pm 0.051$$. Here the first uncertainty is statistical, the second is the experimental systematic, and the third is due to the precision of the strong-phase parameters measured from CLEO-c data. The 95% confidence interval on $$phi_3$$ is $$(-29.7,~109.5)^{circ}$$, which is consistent with the current world average.

論文

Beam energy and centrality dependence of direct-photon emission from ultrarelativistic heavy-ion collisions

Adare, A.*; 長谷川 勝一; 今井 憲一; 永宮 正治*; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他666名*

Physical Review Letters, 123(2), p.022301_1 - 022301_10, 2019/07

 被引用回数:3 パーセンタイル:23(Physics, Multidisciplinary)

The PHENIX collaboration presents first measurements of low-momentum ($$0.4 < p_T < 3$$ GeV/$$c$$) direct-photon yields from Au$$+$$Au collisions at $$sqrt{s_{_{NN}}}$$=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au$$+$$Au collisions at $$sqrt{s_{_{NN}}}$$=200. Analyzing the photon yield as a function of the experimental observable $$dN_{rm ch}/deta$$ reveals that the low-momentum ($$>$$1,GeV/$$c$$) direct-photon yield $$dN_{gamma}^{rm dir}/deta$$ is a smooth function of $$dN_{rm ch}/deta$$ and can be well described as proportional to $$(dN_{rm ch}/deta)^alpha$$ with $$alpha{sim}$$1.25. This new scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and Large Hadron Collider, for centrality selected samples, as well as for different, $$A$$$$+$$$$A$$ collision systems. At a given beam energy the scaling also holds for high $$p_T$$ ($$>$$,GeV/$$c$$) but when results from different collision energies are compared, an additional $$sqrt{s_{_{NN}}}$$-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

論文

Energy scan of the $$e^+e^- to h_b(nP) pi^+pi^-$$ $$(n=1,2)$$ cross sections and evidence for $$Upsilon(11020)$$ decays into charged bottomoniumlike states

Mizuk, R.*; 谷田 聖; Belle Collaboration*; 他166名*

Physical Review Letters, 117(14), p.142001_1 - 142001_7, 2016/09

AA2016-0386.pdf:0.36MB

 被引用回数:5 パーセンタイル:46.22(Physics, Multidisciplinary)

Using data collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider, we measure the energy dependence of the $$e^+e^- to h_b(nP) pi^+pi^-$$ $$(n=1,2)$$ cross sections from thresholds up to 11.02 GeV. We find clear $$Upsilon(10860)$$ and $$Upsilon(11020)$$ peaks with little or no continuum contribution. We study the resonant substructure of the $$Upsilon(11020) to h_b(nP) pi^+pi^-$$ transitions and find evidence that they proceed entirely via the intermediate isovector states $$Z_b(10610)$$ and $$Z_b(10650)$$. The relative fraction of these states is loosely constrained by the current data: The hypothesis that only $$Z_b(10610)$$ is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only $$Z_b(10650)$$ is produced is not excluded at a significant level.

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