Author
Y. Hayato
Other affiliations: Kyoto University, KEK, Autonomous University of Madrid ...read more
Bio: Y. Hayato is an academic researcher from University of Tokyo. The author has contributed to research in topics: Neutrino & Neutrino oscillation. The author has an hindex of 58, co-authored 175 publications receiving 12874 citations. Previous affiliations of Y. Hayato include Kyoto University & KEK.
Papers published on a yearly basis
Papers
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Seoul National University1, Kobe University2, University of Washington3, University of California, Irvine4, Chonnam National University5, University of Tokyo6, Kyoto University7, Tohoku University8, Stony Brook University9, Okayama University10, Boston University11, University of Warsaw12, Korea University13, Niigata University14, Dongshin University15, Massachusetts Institute of Technology16, Tokyo University of Science17
TL;DR: The K2K experiment observed indications of neutrino oscillation after 250 km flight of υμ. as mentioned in this paper The observed number of events in the data corresponding to 4.8 x 1019 protons on target is 56, while 80.1 5.4 + 6.2 is expected.
Abstract: The K2K experiment observed indications of neutrino oscillation after 250 km flight of υμ. The observed number of events in the data corresponding to 4.8 x 1019 protons on target is 56, while 80.1 5.4 +6.2 is expected. Both the decrease of the events and observed spectrum shape distortion are consistent with neutrino oscillation. The probability that the observations are statistical fluctuation of non oscillation is less than 1%. The allowed region of oscillation parameters is consistent with the one obtained from the atmospheric neutrino observation. After the accident of Super-Kamiokande (SK) detector, the reconstruction of SK has finished in 2002 and the K2K experiment resumed in December 2002.
702 citations
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University of Tokyo1, Boston University2, Brookhaven National Laboratory3, University of California, Irvine4, California State University, Dominguez Hills5, Chonnam National University6, Duke University7, George Mason University8, Gifu University9, Indiana University10, University of Tsukuba11, Okayama University12, Kobe University13, Kyoto University14, Los Alamos National Laboratory15, Louisiana State University16, University of Maryland, College Park17, University of Minnesota18, Miyagi University of Education19, Stony Brook University20, Nagoya University21, Niigata University22, Osaka University23, Seoul National University24, Shizuoka University25, Sungkyunkwan University26, Tohoku University27, Tokai University28, Tokyo Institute of Technology29, University of Warsaw30, University of Washington31
TL;DR: In this article, a combined analysis of fully-contained, partially-contained and upward-going muon atmospheric neutrino data from a 1489 d exposure of the Super-Kamiokande detector is presented.
Abstract: We present a combined analysis of fully-contained, partially-contained and upward-going muon atmospheric neutrino data from a 1489 d exposure of the Super-Kamiokande detector. The data samples span roughly five decades in neutrino energy, from 100 MeV to 10 TeV. A detailed Monte Carlo comparison is described and presented. The data is fit to the Monte Carlo expectation, and is found to be consistent with neutrino oscillations of {nu}{sub {mu}}{r_reversible}{nu}{sub {tau}} with sin{sup 2}2{theta}>0.92 and 1.5x10{sup -3}<{delta}m{sup 2}<3.4x10{sup -3} eV{sup 2} at 90% confidence level.
701 citations
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TL;DR: In this article, measurements of {nu}{sub {mu}} disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment are presented.
Abstract: We present measurements of {nu}{sub {mu}} disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One-hundred and twelve beam-originated neutrino events are observed in the fiducial volume of Super-Kamiokande with an expectation of 158.1{sub -8.6}{sup +9.2} events without oscillation. A distortion of the energy spectrum is also seen in 58 single-ring muonlike events with reconstructed energies. The probability that the observations are explained by the expectation for no neutrino oscillation is 0.0015% (4.3{sigma}). In a two-flavor oscillation scenario, the allowed {delta}m{sup 2} region at sin{sup 2}2{theta}=1 is between 1.9 and 3.5x10{sup -3} eV{sup 2} at the 90% C.L. with a best-fit value of 2.8x10{sup -3} eV{sup 2}.
672 citations
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University of Tokyo1, Boston University2, Brookhaven National Laboratory3, University of California, Irvine4, California State University, Dominguez Hills5, Chonnam National University6, George Mason University7, Gifu University8, Indiana University9, Kobe University10, Kyoto University11, Los Alamos National Laboratory12, Louisiana State University13, University of Maryland, College Park14, Massachusetts Institute of Technology15, University of Minnesota16, Miyagi University of Education17, Stony Brook University18, Nagoya University19, Niigata University20, Osaka University21, Seoul National University22, Shizuoka University23, Sungkyunkwan University24, Tohoku University25, Tokai University26, Tokyo Institute of Technology27, University of Warsaw28, University of Washington29
TL;DR: A dip in the L/E distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation, which constrained nu(micro)<-->nu(tau) neutrinos oscillation parameters.
Abstract: Muon neutrino disappearance probability as a function of neutrino flight length $L$ over neutrino energy $E$ was studied. A dip in the $L/E$ distribution was observed in the data, as predicted from the sinusoidal flavor transition probability of neutrino oscillation. The observed $L/E$ distribution constrained ${\ensuremath{
u}}_{\ensuremath{\mu}}\ensuremath{\leftrightarrow}{\ensuremath{
u}}_{\ensuremath{\tau}}$ neutrino oscillation parameters; $1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}l\ensuremath{\Delta}{m}^{2}l3.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{e}\mathrm{V}}^{2}$ and ${sin }^{2}2\ensuremath{\theta}g0.90$ at 90% confidence level.
522 citations
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TL;DR: The Hyper-Kamiokande (Hyper-K) detector was proposed in this paper as a next generation underground water Cherenkov detector for neutrino oscillation experiments.
Abstract: We propose the Hyper-Kamiokande (Hyper-K) detector as a next generation underground water Cherenkov detector. It will serve as a far detector of a long baseline neutrino oscillation experiment envisioned for the upgraded J-PARC, and as a detector capable of observing -- far beyond the sensitivity of the Super-Kamiokande (Super-K) detector -- proton decays, atmospheric neutrinos, and neutrinos from astronomical origins. The baseline design of Hyper-K is based on the highly successful Super-K, taking full advantage of a well-proven technology. (to be continued)
449 citations
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TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.
Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
33,785 citations
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28,685 citations
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TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These
9,929 citations
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TL;DR: In this article, the Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data were used to constrain the physics of cosmic inflation via Gaussianity, adiabaticity, the power spectrum of primordial fluctuations, gravitational waves, and spatial curvature.
Abstract: The Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data provide stringent limits on deviations from the minimal, six-parameter Λ cold dark matter model. We report these limits and use them to constrain the physics of cosmic inflation via Gaussianity, adiabaticity, the power spectrum of primordial fluctuations, gravitational waves, and spatial curvature. We also constrain models of dark energy via its equation of state, parity-violating interaction, and neutrino properties, such as mass and the number of species. We detect no convincing deviations from the minimal model. The six parameters and the corresponding 68% uncertainties, derived from the WMAP data combined with the distance measurements from the Type Ia supernovae (SN) and the Baryon Acoustic Oscillations (BAO) in the distribution of galaxies, are: Ω b h 2 = 0.02267+0.00058 –0.00059, Ω c h 2 = 0.1131 ± 0.0034, ΩΛ = 0.726 ± 0.015, ns = 0.960 ± 0.013, τ = 0.084 ± 0.016, and at k = 0.002 Mpc-1. From these, we derive σ8 = 0.812 ± 0.026, H 0 = 70.5 ± 1.3 km s-1 Mpc–1, Ω b = 0.0456 ± 0.0015, Ω c = 0.228 ± 0.013, Ω m h 2 = 0.1358+0.0037 –0.0036, z reion = 10.9 ± 1.4, and t 0 = 13.72 ± 0.12 Gyr. With the WMAP data combined with BAO and SN, we find the limit on the tensor-to-scalar ratio of r 1 is disfavored even when gravitational waves are included, which constrains the models of inflation that can produce significant gravitational waves, such as chaotic or power-law inflation models, or a blue spectrum, such as hybrid inflation models. We obtain tight, simultaneous limits on the (constant) equation of state of dark energy and the spatial curvature of the universe: –0.14 < 1 + w < 0.12(95%CL) and –0.0179 < Ω k < 0.0081(95%CL). We provide a set of WMAP distance priors, to test a variety of dark energy models with spatial curvature. We test a time-dependent w with a present value constrained as –0.33 < 1 + w 0 < 0.21 (95% CL). Temperature and dark matter fluctuations are found to obey the adiabatic relation to within 8.9% and 2.1% for the axion-type and curvaton-type dark matter, respectively. The power spectra of TB and EB correlations constrain a parity-violating interaction, which rotates the polarization angle and converts E to B. The polarization angle could not be rotated more than –59 < Δα < 24 (95% CL) between the decoupling and the present epoch. We find the limit on the total mass of massive neutrinos of ∑m ν < 0.67 eV(95%CL), which is free from the uncertainty in the normalization of the large-scale structure data. The number of relativistic degrees of freedom (dof), expressed in units of the effective number of neutrino species, is constrained as N eff = 4.4 ± 1.5 (68%), consistent with the standard value of 3.04. Finally, quantitative limits on physically-motivated primordial non-Gaussianity parameters are –9 < f local NL < 111 (95% CL) and –151 < f equil NL < 253 (95% CL) for the local and equilateral models, respectively.
5,904 citations
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TL;DR: The first direct detection of gravitational waves and the first observation of a binary black hole merger were reported in this paper, with a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ.
Abstract: On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10(-21). It matches the waveform predicted by general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. The signal was observed with a matched-filter signal-to-noise ratio of 24 and a false alarm rate estimated to be less than 1 event per 203,000 years, equivalent to a significance greater than 5.1σ. The source lies at a luminosity distance of 410(-180)(+160) Mpc corresponding to a redshift z=0.09(-0.04)(+0.03). In the source frame, the initial black hole masses are 36(-4)(+5)M⊙ and 29(-4)(+4)M⊙, and the final black hole mass is 62(-4)(+4)M⊙, with 3.0(-0.5)(+0.5)M⊙c(2) radiated in gravitational waves. All uncertainties define 90% credible intervals. These observations demonstrate the existence of binary stellar-mass black hole systems. This is the first direct detection of gravitational waves and the first observation of a binary black hole merger.
4,375 citations