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論文

Formation and evolution of carbonaceous asteroid Ryugu; Direct evidence from returned samples

中村 智樹*; 大澤 崇人; 他219名*

Science, 379(6634), p.eabn8671_1 - eabn8671_14, 2023/02

https://doi.org/10.1126/science.abn8671
 被引用回数：98 パーセンタイル：99.99(Multidisciplinary Sciences)

1から8mmのリュウグウ粒子16個の鉱物学的,岩石学的、および物理的特性は、それらがCIコンドライトに最も類似していることを示している。磁硫鉄鉱中のCO$$_{2}$$含有水の存在は、母天体が太陽系星雲のH$$_{2}$$OおよびCO$$_{2}$$のスノーラインを越えた領域で形成したことを示しており、ここでは、リュウグウの鉱物学に基づくと、小さなコンドリュールやCa, Alを含む非常に限られた量の高温物質がある。流体-岩石反応は、低温,高pH、および水/岩石の質量比が1未満の還元条件で発生し、リュウグウのサンプルで最も変化の少ない断片として残っているかんらん石-輝石に富む岩相を、リュウグウサンプルの主要な岩相であるフィロケイ酸塩-炭酸塩に富むものに変えた。リュウグウの母体の流体から磁鉄鉱が結晶化したとき、原始太陽系星雲はまだ存在していた可能性がある。

論文

Search for $$B^{0} to tau^pm ell^mp$$ ($$ell=e,mu$$) with a hadronic tagging method at Belle

Atmacan, H.*; 谷田 聖; Belle Collaboration*; 他219名*

Physical Review D, 104(9), p.L091105_1 - L091105_9, 2021/11

https://doi.org/10.1103/PhysRevD.104.L091105
 被引用回数：3 パーセンタイル：20.63(Astronomy & Astrophysics)

We present a search for the lepton-flavor-violating decays $$B^{0} to tau^pm ell^mp$$, where $$ell=(e,,mu)$$, using the full data sample of $$772 times 10^6$$ $$B overline{B}$$ pairs recorded by 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. The $$tau^pm$$ lepton is reconstructed indirectly using the momentum of the reconstructed $$B$$ and that of the $$ell^mp$$ from the signal decay. We find no evidence for $$B^{0} to tau^pm ell^mp$$ decays and set upper limits on their branching fractions at 90% confidence level of $$cal B$$($$B^{0} to tau^pm mu^{mp}$$)$$ < 1.5 times 10^{-5}$$ and $$cal B$$($$B^{0} to tau^pm e^{mp}$$)$$ < 1.6 times 10^{-5}$$.

論文

Search for the dark photon in $$B^0 to A^{prime} A^{prime}$$, $$A^{prime} to e^+ e^-$$, $$mu^+ mu^-$$, and $$pi^+ pi^-$$ decays at Belle

Park, S.-H.*; 谷田 聖; Belle Collaboration*; 他217名*

Journal of High Energy Physics (Internet), 2021(4), p.191_1 - 191_15, 2021/04

https://doi.org/10.1007/JHEP04(2021)191
 被引用回数：0 パーセンタイル：0.01(Physics, Particles & Fields)

We present a search for the dark photon $$A^{prime}$$ in the $$B^0 to A^{prime} A^{prime}$$ decays, where $$A^{prime}$$ subsequently decays to $$e^+e^-$$, $$mu^+ mu^-$$, and $$pi^+ pi^-$$. The search is performed by analyzing $$772 times 10^6$$ $$Boverline{B}$$ events collected by the Belle detector at the KEKB $$e^+ e^-$$ energy-asymmetric collider at the $$Upsilon (4S)$$ resonance. No signal is found in the dark photon mass range $$0.01~mathrm{GeV}/c^2 le m_{A^{prime}} le 2.62~mathrm{GeV}/c^2$$, and we set upper limits of the branching fraction of $$B^0 to A^{prime} A^{prime}$$ at the 90% confidence level. The products of branching fractions, $$mathcal{B}(B^0 to A^{prime} A^{prime}) times mathcal{B}(A^{prime} to e^+ e^-)^2$$ and $$mathcal{B}(B^0 to A^{prime} A^{prime}) times mathcal{B}(A^{prime} to mu^+ mu^-)^2$$, have limits of the order of $$10^{-8}$$ depending on the $$A^{prime}$$ mass. Furthermore, considering $$A^{prime}$$ decay rate to each pair of charged particles, the upper limits of $$mathcal{B}(B^0 to A^{prime} A^{prime})$$ are of the order of $$10^{-8}$$-$$10^{-5}$$. From the upper limits of $$mathcal{B}(B^0 to A^{prime} A^{prime})$$, we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of $$10^{-2}$$-$$10^{-1}$$ at $$m_{h'} simeq m_{B^0} pm 40~mathrm{MeV}/c^2$$ and $$10^{-1}$$-$$1$$ at $$m_{h'} simeq m_{B^0} pm 3~mathrm{GeV}/c^2$$.

論文

Test of lepton flavor universality and search for lepton flavor violation in $$B to K ellell$$ decays

Choudhury, S.*; 谷田 聖; Belle Collaboration*; 他221名*

Journal of High Energy Physics (Internet), 2021(3), p.105_1 - 105_19, 2021/03

https://doi.org/10.1007/JHEP03(2021)105
 被引用回数：28 パーセンタイル：92.09(Physics, Particles & Fields)

We present measurements of the branching fractions for the decays $$Bto K mu^{+}mu^{-}$$ and $$Bto K e^{+}e^{-}$$, and their ratio ($$R_{K}$$), using a data sample of 711 $${rm fb^{-1}}$$ that contains $$772 times 10^{6}$$ $$Bbar{B}$$ events. The data were collected at the $$Upsilon(4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. The ratio $$R_{K}$$ is measured in five bins of dilepton invariant-mass-squared ($$q^{2}$$): $$q^{2} in (0.1, 4.0), (4.0, 8.12), (1.0, 6.0)$$, $$(10.2, 12.8)$$ and ($$ > 14.18) ;{rm GeV^{2}}/c^{4}$$, along with the whole $$q^2$$ region. The $$R_{K}$$ value for $$q^{2} in (1.0, 6.0) ;{rm GeV^{2}}/c^{4}$$ is $$1.03^{+0.28}_{-0.24} pm 0.01$$. The first and second uncertainties listed are statistical and systematic, respectively. All results for $$R_{K}$$ are consistent with Standard Model predictions. We also measure $$C!P$$-averaged isospin asymmetries in the same $$q^{2}$$ bins. The results are consistent with a null asymmetry, with the largest difference of 2.6 standard deviations occurring for the $$q^{2}in(1.0,6.0) ;{rm GeV^{2}}/c^{4}$$ bin in the mode with muon final states. The measured differential branching fractions, $${dcal B}/{dq^{2}}$$, are consistent with theoretical predictions for charged $$B$$ decays, while the corresponding values are below the expectations for neutral $$B$$ decays. We have also searched for lepton-flavor-violating $$B rightarrow Kmu^{pm}e^{mp}$$ decays and set $$90%$$ confidence-level upper limits on the branching fraction in the range of $$10^{-8}$$ for $$B^{+} rightarrow K^{+}mu^{pm}e^{mp}$$, and $$B^{0} rightarrow K^{0}mu^{pm}e^{mp}$$ modes.

論文

First evidence for cos 2$$beta >$$ 0 and resolution of the Cabibbo-Kobayashi-Maskawa Quark-Mixing Unitarity Triangle ambiguity

足立 一郎*; 谷田 聖; Belle Collaboration*; 他421名*

Physical Review Letters, 121(26), p.261801_1 - 261801_11, 2018/12

AA2018-0657.pdf:0.85MB

https://doi.org/10.1103/PhysRevLett.121.261801
 被引用回数：9 パーセンタイル：57.38(Physics, Multidisciplinary)

We present first evidence that the cosine of the $$CP$$-violating weak phase $$2beta$$ is positive, and hence exclude trigonometric multifold solutions of the CKM Unitarity Triangle using a time-dependent Dalitz plot analysis of $$B^{0} to D^{(*)} h^{0}$$ with $$D to K_{S}^{0} pi^{+} pi^{-}$$ decays, where $$h^{0} in {pi^{0}, eta, omega }$$ denotes a light unflavored and neutral hadron. The measurement is performed combining the final data sets of the BaBar and Belle experiments collected at the $$Upsilon(4S)$$ resonance at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain $$( 471 pm 3 )times 10^6, Bbar{B}$$ pairs recorded by the BaBar detector and $$(772 pm 11)times 10^6, Bbar{B}$$ pairs recorded by the Belle detector. The results of the measurement are $$sin{2beta} = 0.80 pm 0.14 ,(rm{stat.}) pm 0.06 ,(rm{syst.}) pm 0.03 ,(rm{model})$$ 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 $$beta$$ of the CKM Unitarity Triangle is $$beta = left( 22.5 pm 4.4 ,(rm{stat.}) pm 1.2 ,(rm{syst.}) pm 0.6 ,(rm{model}) right)^{circ}$$. The quoted model uncertainties are due to the composition of the $$D^{0} to K_{S}^{0} pi^{+} pi^{-}$$ decay amplitude model, which is newly established by performing a Dalitz plot amplitude analysis using a high-statistics $$e^{+}e^{-} to cbar{c}$$ data sample. CP violation is observed in $$B^{0} to D^{(*)} h^{0}$$ decays at the level of $$5.1$$ standard deviations. The significance for $$cos{2beta} > 0$$ is $$3.7$$ standard deviations. The trigonometric multifold solution $$pi/2 - beta = (68.1 pm 0.7)^{circ}$$ is excluded at the level of $$7.3$$ standard deviations. The measurement resolves an ambiguity in the determination of the apex of the CKM Unitarity Triangle.

論文

Search for the lepton-flavor-violating decay $$B^{0}to K^{ast 0} mu^{pm} e^{mp}$$

Sandilya, S.*; 谷田 聖; Belle Collaboration*; 他211名*

Physical Review D, 98(7), p.071101_1 - 071101_8, 2018/10

AA2018-0631.pdf:0.47MB

https://doi.org/10.1103/PhysRevD.98.071101
 被引用回数：5 パーセンタイル：28.36(Astronomy & Astrophysics)

We have searched for the lepton-flavor-violating decay $$B^{0}to K^{ast 0} mu^{pm} e^{mp}$$ using a data sample of 711 fb$$^{-1}$$ that contains $$772 times 10^{6}$$ $$Bbar{B}$$ pairs. The data were collected near the $$Upsilon (4S)$$ resonance with the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider. No signals were observed, and we set 90% confidence level upper limits on the branching fractions of $${cal B}(B^{0}to K^{ast 0} mu^{+} e^{-}) < 1.2times 10^{-7}$$, $${cal B}(B^{0}to K^{ast 0} mu^{-} e^{+}) < 1.6times 10^{-7}$$, and, for both decays combined, $${cal B}(B^{0}to K^{ast 0} mu^{pm} e^{mp}) < 1.8times 10^{-7}$$. These are the most stringent limits on these decays to date.

論文

RHIC forward experiment to study $$sqrt{s}$$ dependence of forward particle production

さこ 隆志*; 谷田 聖; 他21名*

EPJ Web of Conferences, 145, p.10005_1 - 10005_4, 2017/06

BB2017-0841.pdf:0.4MB

https://doi.org/10.1051/epjconf/201614510005

The Relativistic Heavy Ion Collider forward experiment is ready to take data in the RHIC Run2017 $$sqrt{s} = 510$$ GeV $$p$$-$$p$$ collisions using the LHCf Arm1 detector. New accelerator data are valuable to verify the Feynman scaling of $$pi^0$$ production and to study the evolution of the break of scaling in neutron production. Using the transversely polarized proton beam, asymmetric production of forward neutrons is precisely measured. That is useful to understand the fundamental meson exchange in the proton-proton collisions.

論文

Measurement of long-range angular correlation and quadrupole anisotropy of pions and (anti)protons in central d+Au collisions at $$sqrt{s_{NN}} = 200$$ GeV

Adare, A.*; 今井 憲一; 谷田 聖; PHENIX Collaboration*; 他421名*

Physical Review Letters, 114(19), p.192301_1 - 192301_8, 2015/05

AA2015-0709.pdf:0.4MB

https://doi.org/10.1103/PhysRevLett.114.192301
 被引用回数：133 パーセンタイル：97.3(Physics, Multidisciplinary)

We present azimuthal angular correlations between charged hadrons and energy deposited in calorimeter towers in central $$d$$ + Au and minimum bias $$p+p$$ collisions at $$sqrt{s_{NN}} = 200$$ GeV. The charged hadron is measured at midrapidity $$|eta| < 0.35$$, and the energy is measured at large rapidity ($$-3.7 < eta < -3.1$$, Au-going direction). An enhanced near-side angular correlation across $$|eta| < 2.75$$ is observed in $$d$$+Au collisions. Using the event plane method applied to the Au-going energy distribution, we extract the anisotropy strength $$v_2$$ for inclusive charged hadrons at midrapidity up to $$p_T < 4.5; {rm GeV}/c$$. We also present the measurement of $$v_2$$ for identified $$pi^{pm}$$ and and (anti)protons in central $$d$$ + Au collisions, and observe a mass-ordering pattern similar to that seen in heavy-ion collisions. These results are compared with viscous hydrodynamic calculations and measurements from $$p$$ + Pb at $$sqrt{s_{NN}}$$ = 5.02 TeV. The magnitude of the mass ordering in $$d$$+Au is found to be smaller than that in $$p$$+Pb collisions, which may indicate smaller radial flow in lower energy $$d$$+Au collisions.

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