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論文

Search for $$B^0$$ meson decays into $$Lambda$$ and missing energy with a hadronic tagging method at Belle

Hadjivasiliou, C.*; 谷田 聖; Belle Collaboration*; 他166名*

Physical Review D, 105(5), p.L051101_1 - L051101_8, 2022/03

https://doi.org/10.1103/PhysRevD.105.L051101

We present a search for the decays of $$B^0$$ mesons into a final state containing a $$Lambda$$ baryon and missing energy. These results are obtained from a 711 fb$$^{-1}$$ data sample that contains $$772 times 10^6$$ $$B{kern 0.18em}overline{kern -0.18em B}$$ pairs and was collected near the $$Upsilon(4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider. We use events in which one $$B$$ meson is fully reconstructed in a hadronic decay mode and require the remainder of the event to consist of only a single $$Lambda$$. No evidence for these decays is found and we set $$90%$$ confidence level upper limits on the branching fractions in the range $$2.1$$-$$3.8times 10^{-5}$$. This measurement provides the world's most restrictive limits, with implications for baryogenesis and dark matter production.

論文

Nuclear structure of Te isotopes beyond neutron magic number $$N$$ = 82

Moon, B.*; Jungclaus, A.*; Na$"i$dja, H.*; Gargano, A.*; Lozeva, R.*; Moon, C.-B.*; Orlandi, R.; 他66名*

Physical Review C, 103(3), p.034320_1 - 034320_15, 2021/03

https://doi.org/10.1103/PhysRevC.103.034320
 被引用回数：8 パーセンタイル：72.09(Physics, Nuclear)

At RIKEN RIBF facility, the beta decay of $$^{137}$$Sb and $$^{138}$$Sb were studied and several new excited states were assigned to the level schemes of $$^{137}$$Te and $$^{138}$$Te. The structure of these Te isotopes deduced from the level scheme is compared with state-of-the-art shell-model calculations using different effective interactions. The comparison with calculations permits to determine the spectroscopic factors and deformation of these isotopes close to doubly magic $$^{132}$$Sn.

論文

Observation of a $$bar{K}NN$$ bound state in the $$^{3}$$He $$(K^-, Lambda p)n$$ reaction

山我 拓巳*; 橋本 直; 谷田 聖; 他66名*

Physical Review C, 102(4), p.044002_1 - 044002_14, 2020/10

https://doi.org/10.1103/PhysRevC.102.044002
 被引用回数：18 パーセンタイル：87.01(Physics, Nuclear)

We have performed an exclusive measurement of the $$K^{-}+! ~^{3}{rm He} to Lambda pn$$ reaction at an incident kaon momentum of $$1 {rm GeV}/c$$. In the $$Lambda p$$ invariant mass spectrum, a clear peak was observed below the mass threshold of $$bar{K}+N+N$$, as a signal of the kaonic nuclear bound state, $$bar{K}NN$$. The binding energy, decay width, and $$S$$-wave Gaussian reaction form-factor of this state were observed to be $$B_{K} = 42pm3({rm stat.})^{+3}_{-4}({rm syst.}) {rm MeV}$$, $$Gamma_{K} = 100pm7({rm stat.})^{+19}_{-9}({rm syst.}) {rm MeV}$$, and $$Q_{K} = 383pm11({rm stat.})^{+4}_{-1}({rm syst.}) {rm MeV}/c$$, respectively. The total production cross-section of $$bar{K}NN$$, determined by its $$Lambda p$$ decay mode, was $$sigma^{tot}_{K} cdot BR_{Lambda p} = 9.3pm0.8({rm stat.})^{+1.4}_{-1.0}({rm syst.}) mu{rm b}$$. We estimated the branching ratio of the $$bar{K}NN$$ state to the $$Lambda p$$ and $$Sigma^{0}p$$ decay modes as $$BR_{Lambda p}/BR_{Sigma ^{0}p} sim 1.7$$, by assuming that the physical processes leading to the $$Sigma N!N$$ final states are analogous to those of $$Lambda pn$$.

論文

$$K^-pp$$ bound system at J-PARC

佐久間 史典*; 橋本 直; 谷田 聖; 他66名*

AIP Conference Proceedings 2249, p.020005_1 - 020005_10, 2020/07

https://doi.org/10.1063/5.0008808
 被引用回数：1 パーセンタイル：63.97(Physics, Applied)

The $$bar{K}NN$$ bound system, symbolically denoted as "$$K^-pp$$", is the simplest $$bar{K}$$-nuclear bound system which has been widely discussed as a consequence of the strongly attractive $$bar{K}N$$ interaction in $$I = 0$$ channels. Many theoretical works have pointed out the existence of the "$$K^-pp$$" bound system, but the calculated properties such as the binding energy and the width spread out due to the uncertainty of the $$bar{K}N$$ interaction below the $$bar{K}+N$$ mass threshold. Experimentally, there are several reports on observation of a "$$K^-pp$$" candidate with the binding energy of around 100 MeV, however, no definitive evidence was available so far. At J-PARC, we conducted a experimental search for the "$$K^-pp$$" bound system using $$K^- + ^3$$He reaction at 1.0 GeV/$$c$$ where the "$$K^-pp$$" is expected to be directly produced via the $$(K^-, n)$$ reaction. We finally observed a bound state below the $$K^- +p+p$$ mass threshold in the $$Lambda pn$$ final state, which can be interpreted as the "$$K^- pp$$" bound state. The possible existence of the "$$K^- pp$$" state is discussed from both aspects of production and decay.

論文

$$bar{K}$$-nuclear bound state at J-PARC

佐久間 史典*; 橋本 直; 谷田 聖; 他66名*

JPS Conference Proceedings (Internet), 32, p.010088_1 - 010088_8, 2020/07

https://doi.org/10.7566/JPSCP.32.010088

$$bar{K}$$-nuclear bound states have been widely discussed as a consequence of the strongly attractive $$bar{K}N$$ interaction in $$I = 0$$ channels. Especially, the simplest $$bar{K}$$-nuclear bound state of $$bar{K}NN$$ (denoted as "$$K^-pp$$") has attracted the strong interest both of theoretical and experimental studies. We observed a bound state below the $$K^- + p + p$$ mass threshold with in-flight $$K^-$$ induced reactions on $$^3$$He target, which can be interpreted as the "$$K^-pp$$" bound state. The possible existence of the "$$K^-pp$$" state is discussed from both aspects of production and decay: "$$K^-pp$$" and $$Lambda(1405)p$$ productions, and non-mesonic $$Lambda p$$ and mesonic $$(pi Sigma)^0p$$ decays, respectively.

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

https://doi.org/10.7566/JPSCP.26.023008

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 (Internet), 2019(10), p.178_1 - 178_27, 2019/10

https://doi.org/10.1007/JHEP10(2019)178
 被引用回数：0 パーセンタイル：0.00(Physics, Particles & Fields)

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

https://doi.org/10.1103/PhysRevLett.123.022301
 被引用回数：33 パーセンタイル：85.95(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 $$alpha approx$$ 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 $$p_T$$ ($$>$$5 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

https://doi.org/10.1103/PhysRevLett.117.142001
 被引用回数：8 パーセンタイル：50.68(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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