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論文

Measurement of the branching fraction of $$Lambda_c^+ to p omega$$ decay at Belle

Li, S. X.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 104(7), p.072008_1 - 072008_8, 2021/10

 被引用回数:3 パーセンタイル:28.43(Astronomy & Astrophysics)

Using 980.6 $$rm fb^{-1}$$ of data collected with the Belle detector operating at the KEKB asymmetric-energy $$e^+e^-$$ collider, we present a measurement of the branching fraction of the singly Cabibbo-suppressed decay $$Lambda_c^+ to p omega$$. A clear $$Lambda_c^+$$ signal is observed for $$Lambda_c^+ to p omega$$ with a statistical significance of 9.1 standard deviations, and we measure the ratio of branching fractions $${cal B}(Lambda_c^+ to p omega)/{cal B}(Lambda_c^+ to p K^- pi^+) = (1.32 pm 0.12 (rm stat) pm 0.10 (rm syst))times 10^{-2}$$, from which we infer the branching fraction $${cal B}(Lambda_c^+ to p omega) = (8.27 pm 0.75 (rm stat) pm 0.62 (rm syst) pm 0.42 (rm ref))times 10^{-4}$$. The first quoted uncertainty is statistical, the second systematic, and the third from the reference mode $$Lambda_c^+ to p K^- pi^+$$.

論文

Measurement of the resonant and nonresonant branching ratios in $$Xi_{c}^{0} rightarrow Xi^{0} K^+ K^-$$

McNeil, J. T.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 103(11), p.112002_1 - 112002_11, 2021/06

 被引用回数:3 パーセンタイル:19.82(Astronomy & Astrophysics)

Using the entire data sample of $$980$$ $$rm fb^{-1}$$ integrated luminosity collected with the Belle detector at the KEKB asymmetric-energy $$e^{+}e^{-}$$ collider, we present an amplitude analysis measuring the branching fractions of the Cabibbo-allowed, $$W$$-exchange resonant decay $$Xi_{c}^{0} rightarrow Xi^{0} phi (to K^+ K^-)$$ with a polarized $$phi$$ and the non-resonant decay via a direct process $$Xi_{c}^{0} rightarrow Xi^{0} K^+ K^-$$. We present these measurements, relative to the normalization mode $$Xi^{-}pi^{+}$$, and find branching ratios $$frac{mathcal{B}(Xi_{c}^{0} rightarrow Xi^{0} phi (rightarrow K^{+}K^{-}))}{mathcal{B}(Xi_{c}^{0} rightarrow Xi^{-} pi^{+})}$$ = $${rm 0.036 pm 0.004 (stat.) pm 0.002 (syst.)}$$ and $$frac{mathcal{B}(Xi_{c}^{0} rightarrow Xi^{0} K^{+} K^{-})}{mathcal{B}(Xi_{c}^{0} rightarrow Xi^{-} pi^{+})}$$ = $$ 0.039 pm 0.004 ({rm stat.}) pm 0.002 {rm (syst.)}$$ which suggest that only minor cusping peaks occur in the combinatorial background of $$Omega^{*-} to Xi^{0}K^{-}$$ due to these $$Xi_{c}^{0}$$ decays.

論文

Potential PeVatron supernova remnant G106.3+2.7 seen in the highest-energy gamma rays

雨森 道紘*; 土屋 晴文; Tibet AS$$_{gamma}$$ Collaboration*; 他93名*

Nature Astronomy (Internet), 5(5), p.460 - 464, 2021/05

 被引用回数:66 パーセンタイル:98.88(Astronomy & Astrophysics)

Cosmic rays (protons and other atomic nuclei) are believed to gain energies of petaelectronvolts (PeV) and beyond at astrophysical particle accelerators called "PeVatrons" inside our Galaxy. Although a characteristic feature of a PeVatron is expected to be a hard gamma-ray energy spectrum that extends beyond 100 teraelectronvolts (TeV) without a cut-off, none of the currently known sources exhibit such a spectrum owing to the low maximum energy of accelerated cosmic rays or owing to insufficient detector sensitivity around 100 TeV. Here, we report the observation of gamma-ray emission from the supernova remnant G106.3+2.7 above 10 TeV. This work provides flux data points up to and above 100 TeV and indicates that the very-high-energy gamma-ray emission above 10 TeV is well correlated with a molecular cloud rather than with the pulsar PSR J2229+6114. Regarding the gamma-ray emission mechanism of G106.3+2.7, this morphological feature appears to favour a hadronic origin via the $$pi$$$$^{0}$$ decay caused by accelerated relativistic protons over a leptonic origin via the inverse Compton scattering by relativistic electrons. Furthermore, we point out that an X-ray flux upper limit on the synchrotron spectrum would provide important information to firmly establish the hadronic scenario as the mechanism of particle acceleration at the source.

論文

First detection of sub-PeV diffuse gamma rays from the galactic disk; Evidence for ubiquitous galactic cosmic rays beyond PeV energies

雨森 道紘*; 土屋 晴文; Tibet AS$$_{gamma}$$ Collaboration*; 他93名*

Physical Review Letters, 126(14), p.141101_1 - 141101_7, 2021/04

 被引用回数:119 パーセンタイル:99.56(Physics, Multidisciplinary)

We report, for the first time, the long-awaited detection of diffuse gamma rays with energies between 100 TeV and 1 PeV in the Galactic disk. Particularly, all gamma rays above 398 TeV are observed apart from known TeV gamma-ray sources and compatible with expectations from the hadronic emission scenario in which gamma rays originate from the decay of $$pi0$$'s produced through the interaction of protons with the interstellar medium in the Galaxy. This is strong evidence that cosmic rays are accelerated beyond PeV energies in our Galaxy and spread over the Galactic disk.

論文

Search for $$Omega(2012)to KXi(1530) to KpiXi$$ at Belle

Jia, S.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 100(3), p.032006_1 - 032006_11, 2019/08

 被引用回数:21 パーセンタイル:73.66(Astronomy & Astrophysics)

Using data samples of $$e^+e^-$$ collisions collected at the $$Upsilon(1S)$$, $$Upsilon(2S)$$, and $$Upsilon(3S)$$ resonances with the Belle detector, we search for the three-body decay of the $$Omega(2012)$$ baryon to $$KpiXi$$. This decay is predicted to dominate for models describing the $$Omega(2012)$$ as a $$KXi(1530)$$ molecule. No significant $$Omega(2012)$$ signals are observed in the studied channels, and 90% credibility level upper limits on the ratios of the branching fractions relative to $$K Xi$$ decay modes are obtained.

論文

Nonperturbative-transverse-momentum broadening in dihadron angular correlations in $$sqrt{s_{NN}}=200$$ GeV proton-nucleus collisions

Aidala, C.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他293名*

Physical Review C, 99(4), p.044912_1 - 044912_10, 2019/04

AA2019-0570.pdf:0.56MB

 被引用回数:5 パーセンタイル:47.22(Physics, Nuclear)

The PHENIX collaboration has measured high-$$p_T$$ dihadron correlations in $$p$$$$+$$$$p$$, $$p$$$$+$$Al, and $$p$$$$+$$Au collisions at $$sqrt{s_{_{NN}}}=200$$ GeV. The correlations arise from inter- and intra-jet correlations and thus have sensitivity to nonperturbative effects in both the initial and final states. The distributions of $$p_{rm out}$$, the transverse momentum component of the associated hadron perpendicular to the trigger hadron, are sensitive to initial and final state transverse momenta. These distributions are measured multi-differentially as a function of $$x_E$$, the longitudinal momentum fraction of the associated hadron with respect to the trigger hadron. The near-side $$p_{rm out}$$ widths, sensitive to fragmentation transverse momentum, show no significant broadening between $$p$$$$+$$Au, $$p$$$$+$$Al, and $$p$$$$+$$$$p$$. The away-side nonperturbative $$p_{rm out}$$ widths are found to be broadened in $$p$$$$+$$Au when compared to $$p$$$$+$$$$p$$; however, there is no significant broadening in $$p$$$$+$$Al compared to $$p$$$$+$$$$p$$ collisions. The data also suggest that the away-side $$p_{rm out}$$ broadening is a function of $$N_{rm coll}$$, the number of binary nucleon-nucleon collisions, in the interaction. The potential implications of these results with regard to initial and final state transverse momentum broadening and energy loss of partons in a nucleus, among other nuclear effects, are discussed.

論文

Search for light tetraquark states in $$Upsilon(1S)$$ and $$Upsilon(2S)$$ decays

Jia, S.*; 谷田 聖; Belle Collaboration*; 他193名*

Physical Review D, 96(11), p.112002_1 - 112002_14, 2017/12

AA2018-0579.pdf:1.79MB

 被引用回数:2 パーセンタイル:13.58(Astronomy & Astrophysics)

We search for the $$J^{PC}=0^{--}$$ and $$1^{+-}$$ light tetraquark states with masses up to 2.46~GeV/$$c^2$$ in $$Upsilon(1S)$$ and $$Upsilon(2S)$$ decays with data samples of $$(102pm 2)$$ million and $$(158pm 4)$$ million events, respectively, collected with the Belle detector. No significant signals are observed in any of the studied production modes, and 90% credibility level (C.L.) upper limits on their branching fractions in $$Upsilon(1S)$$ and $$Upsilon(2S)$$ decays are obtained. The inclusive branching fractions of the $$Upsilon(1S)$$ and $$Upsilon(2S)$$ decays into final states with $$f_1(1285)$$ are measured to be $${cal B}(Upsilon(1S)to f_1(1285)+anything)=(46pm28({rm stat.})pm13({rm syst.}))times 10^{-4}$$ and $${cal B}(Upsilon(2S)to f_1(1285)+anything)=(22pm15({rm stat.})pm6.3({rm syst.}))times 10^{-4}$$. The measured $$chi_{b2} to J/psi + anything$$ branching fraction is measured to be $$(1.50pm0.34({rm stat.})pm0.22({rm syst.}))times 10^{-3}$$, and 90% C.L. upper limits for the $$chi_{b0,b1} to J/psi + anything$$ branching fractions are found to be $$2.3times 10^{-3}$$ and $$1.1times 10^{-3}$$, respectively. For $${cal B}(chi_{b1} to omega + anything)$$, the branching fraction is measured to be $$(4.9pm1.3({rm stat.})pm0.6({rm syst.}))times 10^{-2}$$. All results reported here are the first measurements for these modes.

論文

Systematic study of charged-pion and kaon femtoscopy in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; 長谷川 勝一; 今井 憲一; 佐甲 博之; 佐藤 進; 谷田 聖; PHENIX Collaboration*; 他493名*

Physical Review C, 92(3), p.034914_1 - 034914_21, 2015/09

AA2015-0712.pdf:1.48MB

 被引用回数:24 パーセンタイル:81.36(Physics, Nuclear)

We present a systematic study of charged-pion and kaon interferometry in Au + Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV. The kaon mean source radii are found to be larger than pion radii in the outward and longitudinal directions for the same transverse mass; this difference increases for more central collisions. The azimuthal angle dependence of the radii was measured with respect to the second-order event plane and similar oscillations of the source radii were found for pions and kaons. Hydrodynamic models qualitatively describe the similar oscillations of the mean source radii for pions and kaons, but they do not fully describe the transverse-mass dependence of the oscillations.

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