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論文

Measurements of strong-interaction effects in kaonic-helium isotopes at sub-eV precision with X-ray microcalorimeters

橋本 直; 谷田 聖; 他68名*

Physical Review Letters, 128(11), p.112503_1 - 112503_6, 2022/03

We have measured the $$3d to 2p$$ transition X-rays of kaonic $$^3$$He and $$^4$$He atoms using superconducting transition-edge-sensor microcalorimeters with an energy resolution better than 6 eV (FWHM). We determined the energies to be $$6224.5 pm 0.4$$ (stat) $$pm 0.2$$ (syst) eV and $$6463.7pm 0.3$$ (stat) $$pm 0.1$$ (syst) eV, and widths to be $$2.5pm 1.0$$ (stat) $$pm 0.4$$ (syst) eV and $$1.0 pm 0.6$$ (stat) $$pm 0.3$$ (stat) eV, for kaonic $$^3$$He and $$^4$$He, respectively. These values are nearly 10 times more precise than in previous measurements. Our results exclude the large strong-interaction shifts and widths that are suggested by a coupled-channel approach, and agree with calculations based on optical-potential models.

論文

Observation of the radiative decays of $$Upsilon(1S)$$ to $$chi_{c1}$$

Katrenko, P.*; 谷田 聖; Belle Collaboration*; 他168名*

Physical Review Letters, 124(12), p.122001_1 - 122001_7, 2020/03

 被引用回数:2 パーセンタイル:51.78(Physics, Multidisciplinary)

We report the first observation of the radiative decay of the $$Upsilon(1S)$$ into a charmonium state. The statistical significance of the observed signal of $$Upsilon(1S) to gamma chi_{c1}$$ is 6.3 standard deviations including systematics. The branching fraction is calculated to be Br($$Upsilon(1S) to gamma chi_{c1}$$) = $$(4.7^{+2.4}_{-1.8} (stat) ^{+0.4}_{-0.5} (sys)) times 10^{-5}$$. We also searched for $$Upsilon(1S)$$ radiative decays into $$chi_{c0,2}$$ and $$eta_c(1S,2S)$$ and set upper limits on their branching fractions. These results are obtained from a 24.9 fb$$^{-1}$$ data sample collected with the Belle detector at the KEKB asymmetric-energy $$e^+e^-$$ collider at a center-of-mass energy equal to the $$Upsilon(2S)$$ mass using $$Upsilon(1S)$$ tagging by the $$Upsilon(2S) to Upsilon(1S) pi^+pi^-$$ transitions.

論文

Observation of $$Upsilon(4S)to eta' Upsilon(1S)$$

Guido, E.*; 谷田 聖; Belle Collaboration*; 他168名*

Physical Review Letters, 121(6), p.062001_1 - 062001_7, 2018/08

AA2018-0596.pdf:0.37MB

 被引用回数:5 パーセンタイル:47.76(Physics, Multidisciplinary)

We report the first observation of the hadronic transition $$Upsilon(4S)toeta'Upsilon(1S)$$, using 496 fb$$^{-1}$$ data collected at the $$Upsilon(4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. We reconstruct the $$eta'$$ meson through its decays to $$rho^0gamma$$ and to $$pi^+pi^-eta$$, with $$etatogammagamma$$. We measure: $${cal B}(Upsilon(4S)toeta'Upsilon(1S))=(3.43pm 0.88 {rm(stat.)} pm 0.21 {rm(syst.)})times10^{-5}$$, with a significance of 5.7$$sigma$$.

論文

Measurement of emission angle anisotropy via long-range angular correlations with high-$$p_T$$ hadrons in $$d$$$$+$$Au and $$p$$$$+$$$$p$$ collisions at $$sqrt{s_{_{NN}}}=200$$ GeV

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468名*

Physical Review C, 98(1), p.014912_1 - 014912_16, 2018/07

 被引用回数:5 パーセンタイル:49.58(Physics, Nuclear)

We present measurements of two-particle angular correlations between high-transverse-momentum ($$2<p_T<11$$ GeV/$$c$$) $$pi^0$$ observed at midrapidity ($$|eta|<0.35$$) and particles produced either at forward ($$3.1<eta<3.9$$) or backward ($$-3.7<eta<-3.1$$) rapidity in $$d$$$$+$$Au and $$p$$$$+$$$$p$$ collisions at $$sqrt{s_{_{NN}}}=200$$ GeV. The azimuthal angle correlations for particle pairs with this large rapidity gap in the Au-going direction exhibit a ridge-like structure that persists up to $$p_T{approx}6$$ GeV/$$c$$ and which strongly depends on collision centrality, which is a similar characteristic to the hydrodynamical particle flow in A+A collisions. The ridge-like structure is absent in the $$d$$-going direction as well as in $$p$$$$+$$$$p$$ collisions, in the transverse-momentum range studied. The results indicate that the ridge-like structure is shifted in the Au-going direction toward more central collisions, similar to the charged-particle pseudorapidity distributions.

論文

Search for pentaquark $$Theta^+$$ in hadronic reaction at J-PARC

成木 恵*; 杉村 仁志; 今井 憲一; 市川 裕大; 細見 健二; 他68名*

Few-Body Systems, 54(7-10), p.955 - 960, 2013/08

 被引用回数:2 パーセンタイル:22.1(Physics, Multidisciplinary)

J-PARCにおいてペンタクォーク探索実験を行った。測定方法として($$K^-,pi^-$$)方法が用いられ、これまでのSPring-8で行われた光生成反応とは違う反応である。ハドロン反応のほうがより直接的な反応のため、より有意なデータが提供できた。結果として、ペンタクォークは確認できず、生成断面積として、0.26$$mu$$b/srの上限値を与えた。このことにより、SPring-8との違いが考察され、生成反応の違いにより断面積も違うという結果が分かった。

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