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論文

Proof-of-principle experiment for testing strong-field quantum electrodynamics with exotic atoms; High precision X-ray spectroscopy of muonic neon

奥村 拓馬*; 橋本 直; 他40名*

Physical Review Letters, 130(17), p.173001_1 - 173001_7, 2023/04

https://doi.org/10.1103/PhysRevLett.130.173001
 被引用回数：1 パーセンタイル：83.24(Physics, Multidisciplinary)

To test bound-state quantum electrodynamics (BSQED) in the strong-field regime, we have performed high-precision X-ray spectroscopy of the 5$$g$$-4$$f$$ and 5$$f$$-4$$d$$ transitions (BSQED contribution of 2.4 eV and 5.2 eV, respectively) of muonic neon atoms in the low-pressure gas phase without bound electrons. Muonic atoms have been recently proposed as an alternative to few-electron high-Z ions for BSQED tests by focusing on circular Rydberg states where nuclear contributions are negligibly small. We determined the $$5g_{9/2}$$-$$4f_{7/2}$$ transition energy to be 6297.08 $$pm$$ 0.04 (stat.) $$pm$$ 0.13 (syst.) eV using superconducting transition-edge sensor microcalorimeters (5.2-5.5 eV FWHM resolution), which agrees well with the most advanced BSQED theoretical prediction of 6297.26 eV.

論文

Laser-assisted decay spectroscopy for the ground states of $$^{180,182}$$Au

Harding, R. D.*; Andreyev, A. N.; Barzakh, A. E.*; Atanasov, D.*; Cubiss, J. G.*; Van Duppen, P.*; 他40名*

Physical Review C, 102(2), p.024312_1 - 024312_16, 2020/08

https://doi.org/10.1103/PhysRevC.102.024312
 被引用回数：10 パーセンタイル：73.66(Physics, Nuclear)

A detailed nuclear spectroscopy study of $$^{180}$$Au was performed. An $$alpha$$-decay branching ratio of $$0.58(10)$$% and a half-life of $$7.2(5)$$s have been derived. The first measurement of the hyper fine structure for atomic transitions has been also performed, from which the magnetic dipole moment has been extracted. A spin assignment of $$(1^+)$$ is proposed for the ground state of $$^{180}$$Au, with a $$(pi3/2^-$$[532]$$timesnu5/2^-$$[512]$$)$$ configuration.

論文

Measurement of $$cos{2beta}$$ in $$B^{0} to D^{(*)} h^{0}$$ with $$D to K_{S}^{0} pi^{+} pi^{-}$$ decays by a combined time-dependent Dalitz plot analysis of $$B_{A}B_{AR}$$ and Belle data

足立 一郎*; 谷田 聖; Belle Collaboration*; 他406名*

Physical Review D, 98(11), p.112012_1 - 112012_29, 2018/11

AA2018-0713.pdf:4.08MB

https://doi.org/10.1103/PhysRevD.98.112012
 被引用回数：16 パーセンタイル：63.66(Astronomy & Astrophysics)

We report measurements of $$sin{2beta}$$ and $$cos{2beta}$$ from a time-dependent Dalitz plot analysis of $$B^{0} to D^{(*)} h^{0}$$ with $$D to K_{S}^{0} pi^{+} pi^{-}$$ decays, where the light unflavored and neutral hadron $$h^{0}$$ is a $$pi^{0}$$, $$eta$$, or $$omega$$ meson. The analysis is performed with a combination of the final data sets of the BABAR and Belle experiments containing $$471 times 10^{6}$$ and $$772 times 10^{6}$$ $$Bbar{B}$$ pairs collected at the $$Upsilonleft(4Sright)$$ resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. We measure $$sin{2beta} = 0.80 pm 0.14 ,(rm{stat.}) pm 0.06 ,(rm{syst.}) pm 0.03 ,(rm{model})$$ and $$cos{2beta} = 0.91 pm 0.22 ,(rm{stat.}) pm 0.09 ,(rm{syst.}) pm 0.07 ,(rm{model})$$. The result for the direct measurement of the angle is $$beta = left( 22.5 pm 4.4 ,(rm{stat.}) pm 1.2 ,(rm{syst.}) pm 0.6 ,(rm{model}) right)^{circ}$$. The last quoted uncertainties are due to the composition of the $$D^{0} to K_{S}^{0} pi^{+} pi^{-}$$ decay amplitude model, which is newly established by a Dalitz plot amplitude analysis of a high-statistics $$e^{+}e^{-} to cbar{c}$$ data sample as part of this analysis. We find the first evidence for $$cos2beta>0$$ at the level of $$3.7$$ standard deviations. The measurement excludes the trigonometric multifold solution $$pi/2 - beta = (68.1 pm 0.7)^{circ}$$ at the level of $$7.3$$ standard deviations and therefore resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle. The hypothesis of $$beta = 0^{circ}$$ is ruled out at the level of $$5.1$$ standard deviations, and thus $$CP$$ violation is observed in $$B^{0} to D^{(*)} h^{0}$$ decays.

論文

Search for excited state of $$Sigma$$ hypernucleus in the J-PARC E13 experiment

中川 真菜美*; 江川 弘行; 長谷川 勝一; 早川 修平; 細見 健二; Hwang, S.; 市川 裕大; 今井 憲一; 佐甲 博之; 佐藤 進; et al.

JPS Conference Proceedings (Internet), 17, p.012009_1 - 012009_4, 2017/07

https://doi.org/10.7566/JPSCP.17.012009

One of the main items of the J-PARC E13 experiment is the search for excited states of the $$^4_{Sigma}$$He hypernucleus via the $$^4$$He$$(K^-,pi^-)$$ reaction at 1.5 GeV/c. The missing-mass spectrum of the $$^4$$He$$(K^-,pi^-)X$$ reaction was obtained in an angular range from 0 to 20 degrees. We show the count-base spectrum of the missing-mass in the angular range from 2 to 14 degrees. The ground state of $$^4_{Lambda}$$He and $$^4_{Sigma}$$He were clearly observed in the missing-mass spectrum. We also show three missing-mass spectra divided by the reaction angle.

論文

High statistics $$Sigma p$$ scattering experiment using high intensity pion beams at J-PARC

三輪 浩司*; 長谷川 勝一; 早川 修平; 細見 健二; 今井 憲一; 近藤 恭弘; 成木 恵; 佐甲 博之; 佐藤 進; 杉村 仁志; et al.

JPS Conference Proceedings (Internet), 17, p.041002_1 - 041002_6, 2017/07

https://doi.org/10.7566/JPSCP.17.041002

In order to test theoretical frameworks of the Baryon-Baryon ($$BB$$) interactions and to confirm the "Pauli effect between quarks" for the first time, we have proposed an experiment (J-PARC E40) to measure low-energy hyperon-proton scattering cross sections of the $$Sigma^+ p$$, $$Sigma^- p$$ elastic scatterings and the $$Sigma^- p to Lambda n$$ inelastic scattering in the momentum range of $$400 < p ; ({rm MeV}/c) < 700$$ in the laboratory system. Experimentally, we detect two successive reactions of the $$Sigma$$ production $$(pi^{pm}p to K^+Sigma^{pm})$$ and the $$Sigma p$$ scattering ($$Sigma p to Sigma p$$) in the same liquid hydrogen target. The former is measured with two magnetic spectrometers, and the latter with a scattered proton detector (CATCH). By using a high intensity $$pi$$ beam, we estimate that more than 10000 scattering events can be identified. In this experiment, we aim to provide good quality scattering data to test the theoretical models of the $$BB$$ interaction.

論文

Dielectron production in Au + Au 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440名*

Physical Review C, 93(1), p.014904_1 - 014904_34, 2016/01

AA2015-0856.pdf:3.7MB

https://doi.org/10.1103/PhysRevC.93.014904
 被引用回数：48 パーセンタイル：95(Physics, Nuclear)

We present measurements of $$e^+e^-$$ production at midrapidity in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass ($$m_{ee} < 5$$ GeV/$$c^2$$) and pair transverse momentum ($$p_T<5$$ GeV/$$c$$) for minimum bias and for five centrality classes. The $$e^+e^-$$ yield is compared to the expectations from known sources. In the low-mass region ($$m_{ee}=$$0.30-0.76 GeV/$$c^2$$) there is an enhancement that increases with centrality and is distributed over the entire pair $$p_T$$ range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to $$2.3 pm 0.4({rm stat}) pm 0.4({rm syst}) pm 0.2({rm model})$$ or to $$1.7 pm 0.3({rm stat}) pm 0.3({rm syst}) pm 0.2({rm model})$$ for minimum bias collisions when the open heavy-flavor contribution is calculated with pythia or mc@nlo, respectively. The inclusive mass and $$p_T$$ distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the $$rho$$ meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region ($$m_{ee}=$$1.2-2.8 GeV/$$c^2$$), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

論文

Inclusive cross section and double-helicity asymmetry for $$pi^0$$ production at midrapidity in $$p+p$$ collisions at $$sqrt{s}=510$$ 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406名*

Physical Review D, 93(1), p.011501_1 - 011501_8, 2016/01

https://doi.org/10.1103/PhysRevD.93.011501
 被引用回数：37 パーセンタイル：83.53(Astronomy & Astrophysics)

PHENIX measurements are presented for the cross section and double-helicity asymmetry ($$A_{LL}$$) in inclusive $$pi^0$$ production at midrapidity from $$p+p$$ collisions at $$sqrt{s}=510$$ GeV from data taken in 2012 and 2013 at the Relativistic Heavy Ion Collider. The next-to-leading-order perturbative-quantum-chromodynamics theory calculation is in excellent agreement with the presented cross section results. The calculation utilized parton-to-pion fragmentation functions from the recent DSS14 global analysis, which prefer a smaller gluon-to-pion fragmentation function. The $$pi^0; A_{LL}$$ results follow an increasingly positive asymmetry trend with $$p_T$$ and $$sqrt{s}$$ with respect to the predictions and are in excellent agreement with the latest global analysis results. This analysis incorporated earlier results on $$pi^0$$ and jet ALL and suggested a positive contribution of gluon polarization to the spin of the proton $$Delta G$$ for the gluon momentum fraction range $$x>0.05$$. The data presented here extend to a currently unexplored region, down to $$x sim 0.01$$, and thus provide additional constraints on the value of $$Delta G$$.

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