scispace - formally typeset
Search or ask a question
Author

Y. Oyama

Bio: Y. Oyama is an academic researcher from KEK. The author has contributed to research in topics: Super-Kamiokande & Neutrino. The author has an hindex of 13, co-authored 15 publications receiving 3948 citations.

Papers
More filters
Journal ArticleDOI
Y. Fukuda1, M. Ishitsuka1, Yoshitaka Itow1, Takaaki Kajita1, J. Kameda1, K. Kaneyuki1, K. Kobayashi1, Yusuke Koshio1, M. Miura1, S. Moriyama1, Masayuki Nakahata1, S. Nakayama1, A. Okada1, N. Sakurai1, Masato Shiozawa1, Yoshihiro Suzuki1, H. Takeuchi1, Y. Takeuchi1, T. Toshito1, Y. Totsuka1, Shoichi Yamada1, Shantanu Desai2, M. Earl2, E. Kearns2, M. D. Messier2, Kate Scholberg2, Kate Scholberg3, J. L. Stone2, L. R. Sulak2, C. W. Walter2, M. Goldhaber4, T. Barszczak5, David William Casper5, W. Gajewski5, W. R. Kropp5, S. Mine5, D. W. Liu5, L. R. Price5, M. B. Smy5, Henry W. Sobel5, M. R. Vagins5, Todd Haines5, D. Kielczewska5, K. S. Ganezer6, W. E. Keig6, R. W. Ellsworth7, S. Tasaka8, A. Kibayashi, John G. Learned, S. Matsuno, D. Takemori, Y. Hayato, T. Ishii, Takashi Kobayashi, Koji Nakamura, Y. Obayashi, Y. Oyama, A. Sakai, Makoto Sakuda, M. Kohama9, Atsumu Suzuki9, T. Inagaki10, Tsuyoshi Nakaya10, K. Nishikawa10, E. Blaufuss11, S. Dazeley11, R. Svoboda11, J. A. Goodman12, G. Guillian12, G. W. Sullivan12, D. Turcan12, Alec Habig13, J. Hill14, C. K. Jung14, K. Martens15, K. Martens14, Magdalena Malek14, C. Mauger14, C. McGrew14, E. Sharkey14, B. Viren14, C. Yanagisawa14, C. Mitsuda16, K. Miyano16, C. Saji16, T. Shibata16, Y. Kajiyama17, Y. Nagashima17, K. Nitta17, M. Takita17, Minoru Yoshida17, Heekyong Kim18, Soo-Bong Kim18, J. Yoo18, H. Okazawa, T. Ishizuka19, M. Etoh20, Y. Gando20, Takehisa Hasegawa20, Kunio Inoue20, K. Ishihara20, Tomoyuki Maruyama20, J. Shirai20, A. Suzuki20, Masatoshi Koshiba1, Y. Hatakeyama21, Y. Ichikawa21, M. Koike21, Kyoshi Nishijima21, H. Fujiyasu22, Hirokazu Ishino22, M. Morii22, Y. Watanabe22, U. Golebiewska23, S. C. Boyd24, A. L. Stachyra24, R. J. Wilkes24, B. Lee 
TL;DR: Solar neutrino measurements from 1258 days of data from the Super-Kamiokande detector are presented and the recoil electron energy spectrum is consistent with no spectral distortion.
Abstract: Solar neutrino measurements from 1258days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0{endash}20.0MeV. The measured solar neutrino flux is 2.32{+-}0.03(stat){sup +0.08}{sub {minus}0.07}(syst){times}10{sup 6} cm{sup {minus}2}s{sup {minus}1} , which is 45.1{+-}0.5(stat ){sup +1.6}{sub {minus}1.4}(syst) % of that predicted by the BP2000 SSM. The day vs night flux asymmetry ({Phi}{sub n}{minus}{Phi}{sub d})/ {Phi}{sub average} is 0.033{+-}0.022(stat){sup +0.013}{sub {minus}0.012}(syst) . The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L.upper limit of 40{times}10{sup 3} cm{sup {minus}2}s{sup {minus}1} , which is 4.3times the BP2000 SSM prediction.

878 citations

Journal ArticleDOI
S. Fukuda1, Y. Fukuda1, T. Hayakawa1, E. Ichihara1  +183 moreInstitutions (28)
TL;DR: Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons as discussed by the authors, which collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency.
Abstract: Super-Kamiokande is the world's largest water Cherenkov detector, with net mass 50,000 tons. During the period April, 1996 to July, 2001, Super-Kamiokande I collected 1678 live-days of data, observing neutrinos from the Sun, Earth's atmosphere, and the K2K long-baseline neutrino beam with high efficiency. These data provided crucial information for our current understanding of neutrino oscillations, as well as setting stringent limits on nucleon decay. In this paper, we describe the detector in detail, including its site, configuration, data acquisition equipment, online and offline software, and calibration systems which were used during Super-Kamiokande I.

708 citations

Journal ArticleDOI
S. Fukuda1, Y. Fukuda1, M. Ishitsuka1, Yoshitaka Itow1, Takaaki Kajita1, J. Kameda1, K. Kaneyuki1, K. Kobayashi1, Yusuke Koshio1, M. Miura1, S. Moriyama1, Masayuki Nakahata1, S. Nakayama1, Toshio Namba1, A. Okada1, N. Sakurai1, Masato Shiozawa1, Yoshihiro Suzuki1, H. Takeuchi1, Y. Takeuchi1, Y. Totsuka1, Shoichi Yamada1, Shantanu Desai2, M. Earl2, E. Kearns2, M. D. Messier2, J. L. Stone2, L. R. Sulak2, C. W. Walter2, M. Goldhaber3, T. Barszczak4, David William Casper4, W. Gajewski4, W. R. Kropp4, S. Mine4, D. W. Liu4, M. B. Smy4, Henry W. Sobel4, M. R. Vagins4, A. M. Gago5, K. S. Ganezer5, W. E. Keig5, R. W. Ellsworth6, S. Tasaka7, A. Kibayashi8, John G. Learned8, S. Matsuno8, D. Takemori8, Y. Hayato9, T. Ishii9, Takashi Kobayashi9, T. Maruyama9, Koji Nakamura9, Y. Obayashi9, Y. Obayashi1, Y. Oyama9, Makoto Sakuda9, Minoru Yoshida9, M. Kohama10, T. Iwashita10, Atsumu Suzuki10, A. K. Ichikawa9, A. K. Ichikawa11, T. Inagaki11, I. Kato11, Tsuyoshi Nakaya11, K. Nishikawa11, Todd Haines4, Todd Haines12, S. Dazeley13, S. Hatakeyama13, R. Svoboda13, E. Blaufuss14, M. L. Chen14, J. A. Goodman14, G. Guillian14, G. W. Sullivan14, D. Turč14, Kate Scholberg15, Alec Habig16, M. Ackermann17, J. Hill17, C. K. Jung17, Magdalena Malek17, K. Martens17, C. Mauger17, C. McGrew17, E. Sharkey17, B. Viren3, B. Viren17, C. Yanagisawa17, T. Toshito18, C. Mitsuda19, K. Miyano19, C. Saji19, T. Shibata19, Y. Kajiyama20, Y. Nagashima20, K. Nitta20, M. Takita20, Hyosun Kim21, S. B. Kim21, J. Yoo21, H. Okazawa, T. Ishizuka22, M. Etoh23, Y. Gando23, Takehisa Hasegawa23, Kunio Inoue23, K. Ishihara23, J. Shirai23, A. Suzuki23, Masatoshi Koshiba1, Y. Hatakeyama24, Y. Ichikawa24, M. Koike24, Kyoshi Nishijima24, Hirokazu Ishino25, Mikio Morii25, R. Nishimura25, Y. Watanabe25, D. Kielczewska4, D. Kielczewska26, H. G. Berns27, S. C. Boyd27, A. L. Stachyra27, R. J. Wilkes27 
TL;DR: In this paper, a number of different fits to solar neutrino mixing and mass square difference were performed using 1496 days of Super-Kamiokande-I's solar NE data.

680 citations

Journal ArticleDOI
S. Fukuda1, Y. Fukuda1, M. Ishitsuka1, Yoshitaka Itow1, Takaaki Kajita1, J. Kameda1, K. Kaneyuki1, K. Kobayashi1, Yusuke Koshio1, M. Miura1, S. Moriyama1, Masayuki Nakahata1, S. Nakayama1, Y. Obayashi1, A. Okada1, Ko Okumura1, N. Sakurai1, Masato Shiozawa1, Yoshihiro Suzuki1, H. Takeuchi1, Y. Takeuchi1, T. Toshito1, Y. Totsuka1, Shoichi Yamada1, M. Earl2, Alec Habig2, Alec Habig3, E. Kearns2, M. D. Messier2, Kate Scholberg2, J. L. Stone2, L. R. Sulak2, C. W. Walter2, M. Goldhaber4, T. Barszczak5, David William Casper5, W. Gajewski5, W. R. Kropp5, S. Mine5, L. R. Price5, M. B. Smy5, Henry W. Sobel5, M. R. Vagins5, K. S. Ganezer6, W. E. Keig6, R. W. Ellsworth7, S. Tasaka8, A. Kibayashi9, John G. Learned9, S. Matsuno9, D. Takemori9, Y. Hayato, T. Ishii, Takashi Kobayashi, Koji Nakamura, Y. Oyama, A. Sakai, Makoto Sakuda, Osamu Sasaki, M. Kohama10, Atsumu Suzuki10, T. Inagaki11, K. Nishikawa11, Todd Haines12, Todd Haines5, E. Blaufuss13, B. K. Kim13, R. Sanford13, R. Svoboda13, M. L. Chen14, J. A. Goodman14, G. Guillian14, G. W. Sullivan14, J. Hill15, C. K. Jung15, K. Martens15, Magdalena Malek15, C. Mauger15, C. McGrew15, E. Sharkey15, B. Viren15, C. Yanagisawa15, M. Kirisawa16, S. Inaba16, C. Mitsuda16, K. Miyano16, H. Okazawa16, C. Saji16, M. Takahashi16, M. Takahata16, Y. Nagashima17, K. Nitta17, M. Takita17, Minoru Yoshida17, Soo-Bong Kim18, T. Ishizuka19, M. Etoh20, Y. Gando20, Takehisa Hasegawa20, Kunio Inoue20, K. Ishihara20, T. Maruyama20, J. Shirai20, A. Suzuki20, Masatoshi Koshiba1, Y. Hatakeyama21, Y. Ichikawa21, M. Koike21, Kyoshi Nishijima21, H. Fujiyasu22, Hirokazu Ishino22, M. Morii22, Y. Watanabe22, U. Golebiewska23, D. Kielczewska5, D. Kielczewska23, S. C. Boyd24, A. L. Stachyra24, R. J. Wilkes24, K. K. Young24 
TL;DR: Using data recorded in 1100 live days of the Super-Kamiokande detector, three complementary data samples are used to study the difference in zenith angle distribution due to neutral currents and matter effects and find no evidence favoring sterile neutrinos, and reject the hypothesis at the 99% confidence level.
Abstract: The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau neutrinos or sterile neutrinos, as both hypotheses fit the data. Using data recorded in 1100 live days of the Super-Kamiokande detector, we use three complementary data samples to study the difference in zenith angle distribution due to neutral currents and matter effects. We find no evidence favoring sterile neutrinos, and reject the hypothesis at the $99%$ confidence level. On the other hand, we find that oscillation between muon and tau neutrinos suffices to explain all the results in hand.

568 citations

Journal ArticleDOI
S. Fukuda1, Y. Fukuda1, M. Ishitsuka1, Yoshitaka Itow1, Takaaki Kajita1, J. Kameda1, K. Kaneyuki1, K. Kobayashi1, Yusuke Koshio1, M. Miura1, S. Moriyama1, Masayuki Nakahata1, S. Nakayama1, A. Okada1, N. Sakurai1, Masato Shiozawa1, Yoshihiro Suzuki1, H. Takeuchi1, Y. Takeuchi1, T. Toshito1, Y. Totsuka1, Shoichi Yamada1, Shantanu Desai2, M. Earl2, E. Kearns2, M. D. Messier2, Kate Scholberg3, Kate Scholberg2, J. L. Stone2, L. R. Sulak2, C. W. Walter2, M. Goldhaber4, T. Barszczak5, David William Casper5, W. Gajewski5, W. R. Kropp5, S. Mine5, D. W. Liu5, L. R. Price5, M. B. Smy5, Henry W. Sobel5, M. R. Vagins5, K. S. Ganezer6, W. E. Keig6, R. W. Ellsworth7, S. Tasaka8, A. Kibayashi, John G. Learned, S. Matsuno, D. Takemori, Y. Hayato, T. Ishii, Takashi Kobayashi, Koji Nakamura, Y. Obayashi, Y. Oyama, A. Sakai, Makoto Sakuda, M. Kohama9, Atsumu Suzuki9, T. Inagaki10, Tsuyoshi Nakaya10, K. Nishikawa10, Todd Haines11, Todd Haines5, E. Blaufuss12, E. Blaufuss13, S. Dazeley13, K. B. Lee14, K. B. Lee13, R. Svoboda13, J. A. Goodman12, G. Guillian12, G. W. Sullivan12, D. Turcan12, Alec Habig15, J. Hill16, C. K. Jung16, K. Martens17, K. Martens16, Magdalena Malek16, C. Mauger16, C. McGrew16, E. Sharkey16, B. Viren16, C. Yanagisawa16, C. Mitsuda18, K. Miyano18, C. Saji18, T. Shibata18, Y. Kajiyama19, Y. Nagashima19, K. Nitta19, M. Takita19, Minoru Yoshida19, Heekyong Kim20, Soo-Bong Kim20, J. Yoo20, H. Okazawa, T. Ishizuka21, M. Etoh22, Y. Gando22, Takehisa Hasegawa22, Kunio Inoue22, K. Ishihara22, Tomoyuki Maruyama22, J. Shirai22, A. Suzuki22, Masatoshi Koshiba1, Y. Hatakeyama23, Y. Ichikawa23, M. Koike23, Kyoshi Nishijima23, H. Fujiyasu24, Hirokazu Ishino24, M. Morii24, Y. Watanabe24, U. Golebiewska25, D. Kielczewska5, D. Kielczewska25, S. C. Boyd26, A. L. Stachyra26, R. J. Wilkes26, K. K. Young26 
TL;DR: The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way, and two allowed regions at large mixing are found.
Abstract: We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found

515 citations


Cited by
More filters
Journal ArticleDOI
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

Journal ArticleDOI
Nabila Aghanim1, Yashar Akrami2, Yashar Akrami3, Yashar Akrami4  +229 moreInstitutions (70)
TL;DR: In this article, the authors present cosmological parameter results from the full-mission Planck measurements of the cosmic microwave background (CMB) anisotropies, combining information from the temperature and polarization maps and the lensing reconstruction.
Abstract: We present cosmological parameter results from the final full-mission Planck measurements of the cosmic microwave background (CMB) anisotropies, combining information from the temperature and polarization maps and the lensing reconstruction Compared to the 2015 results, improved measurements of large-scale polarization allow the reionization optical depth to be measured with higher precision, leading to significant gains in the precision of other correlated parameters Improved modelling of the small-scale polarization leads to more robust constraints on manyparameters,withresidualmodellinguncertaintiesestimatedtoaffectthemonlyatthe05σlevelWefindgoodconsistencywiththestandard spatially-flat6-parameter ΛCDMcosmologyhavingapower-lawspectrumofadiabaticscalarperturbations(denoted“base ΛCDM”inthispaper), from polarization, temperature, and lensing, separately and in combination A combined analysis gives dark matter density Ωch2 = 0120±0001, baryon density Ωbh2 = 00224±00001, scalar spectral index ns = 0965±0004, and optical depth τ = 0054±0007 (in this abstract we quote 68% confidence regions on measured parameters and 95% on upper limits) The angular acoustic scale is measured to 003% precision, with 100θ∗ = 10411±00003Theseresultsareonlyweaklydependentonthecosmologicalmodelandremainstable,withsomewhatincreasederrors, in many commonly considered extensions Assuming the base-ΛCDM cosmology, the inferred (model-dependent) late-Universe parameters are: HubbleconstantH0 = (674±05)kms−1Mpc−1;matterdensityparameterΩm = 0315±0007;andmatterfluctuationamplitudeσ8 = 0811±0006 We find no compelling evidence for extensions to the base-ΛCDM model Combining with baryon acoustic oscillation (BAO) measurements (and consideringsingle-parameterextensions)weconstraintheeffectiveextrarelativisticdegreesoffreedomtobe Neff = 299±017,inagreementwith the Standard Model prediction Neff = 3046, and find that the neutrino mass is tightly constrained toPmν < 012 eV The CMB spectra continue to prefer higher lensing amplitudesthan predicted in base ΛCDM at over 2σ, which pulls some parameters that affect thelensing amplitude away from the ΛCDM model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) BAOdataThejointconstraintwithBAOmeasurementsonspatialcurvatureisconsistentwithaflatuniverse, ΩK = 0001±0002Alsocombining with Type Ia supernovae (SNe), the dark-energy equation of state parameter is measured to be w0 = −103±003, consistent with a cosmological constant We find no evidence for deviations from a purely power-law primordial spectrum, and combining with data from BAO, BICEP2, and Keck Array data, we place a limit on the tensor-to-scalar ratio r0002 < 006 Standard big-bang nucleosynthesis predictions for the helium and deuterium abundances for the base-ΛCDM cosmology are in excellent agreement with observations The Planck base-ΛCDM results are in good agreement with BAO, SNe, and some galaxy lensing observations, but in slight tension with the Dark Energy Survey’s combined-probe results including galaxy clustering (which prefers lower fluctuation amplitudes or matter density parameters), and in significant, 36σ, tension with local measurements of the Hubble constant (which prefer a higher value) Simple model extensions that can partially resolve these tensions are not favoured by the Planck data

4,688 citations

Journal ArticleDOI
Nabila Aghanim1, Yashar Akrami2, Yashar Akrami3, Yashar Akrami4  +229 moreInstitutions (70)
TL;DR: In this paper, the cosmological parameter results from the final full-mission Planck measurements of the CMB anisotropies were presented, with good consistency with the standard spatially-flat 6-parameter CDM cosmology having a power-law spectrum of adiabatic scalar perturbations from polarization, temperature, and lensing separately and in combination.
Abstract: We present cosmological parameter results from the final full-mission Planck measurements of the CMB anisotropies. We find good consistency with the standard spatially-flat 6-parameter $\Lambda$CDM cosmology having a power-law spectrum of adiabatic scalar perturbations (denoted "base $\Lambda$CDM" in this paper), from polarization, temperature, and lensing, separately and in combination. A combined analysis gives dark matter density $\Omega_c h^2 = 0.120\pm 0.001$, baryon density $\Omega_b h^2 = 0.0224\pm 0.0001$, scalar spectral index $n_s = 0.965\pm 0.004$, and optical depth $\tau = 0.054\pm 0.007$ (in this abstract we quote $68\,\%$ confidence regions on measured parameters and $95\,\%$ on upper limits). The angular acoustic scale is measured to $0.03\,\%$ precision, with $100\theta_*=1.0411\pm 0.0003$. These results are only weakly dependent on the cosmological model and remain stable, with somewhat increased errors, in many commonly considered extensions. Assuming the base-$\Lambda$CDM cosmology, the inferred late-Universe parameters are: Hubble constant $H_0 = (67.4\pm 0.5)$km/s/Mpc; matter density parameter $\Omega_m = 0.315\pm 0.007$; and matter fluctuation amplitude $\sigma_8 = 0.811\pm 0.006$. We find no compelling evidence for extensions to the base-$\Lambda$CDM model. Combining with BAO we constrain the effective extra relativistic degrees of freedom to be $N_{\rm eff} = 2.99\pm 0.17$, and the neutrino mass is tightly constrained to $\sum m_ u< 0.12$eV. The CMB spectra continue to prefer higher lensing amplitudes than predicted in base -$\Lambda$CDM at over $2\,\sigma$, which pulls some parameters that affect the lensing amplitude away from the base-$\Lambda$CDM model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) BAO data. (Abridged)

3,077 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigate the sequence of assumptions and corrections that together affect the cosmic star formation history (SFH) normalization to test their accuracy, both in this redshift range and beyond.
Abstract: Strong constraints on the cosmic star formation history (SFH) have recently been established using ultraviolet and far-infrared measurements, refining the results of numerous measurements over the past decade. The data show a compellingly consistent picture of the SFH out to redshift z ≈ 6, with especially tight constraints for z 1. We fit these data with simple analytical forms and derive conservative uncertainties. Since the z 1 SFH data are quite precise, we investigate the sequence of assumptions and corrections that together affect the SFH normalization to test their accuracy, both in this redshift range and beyond. As lower limits on this normalization, we consider the evolution in stellar and metal mass densities, and supernova rate density, finding it unlikely that the SFH normalization is much lower than indicated by our direct fit. As a corresponding upper limit on the SFH normalization, we consider the Super-Kamiokande limit on the electron antineutrino (e) flux from past core-collapse supernovae, which applies primarily to z 1. We find consistency with the SFH only if the neutrino temperatures from supernova events are relatively modest. Constraints on the assumed initial mass function (IMF) also become apparent. The traditional Salpeter IMF, assumed for convenience by many authors, is known to be a poor representation at low stellar masses (1 M☉), and we show that recently favored IMFs are also constrained. In particular, somewhat shallow, or top-heavy, IMFs may be preferred, although they cannot be too top-heavy. To resolve the outstanding issues, improved data are called for on the supernova rate density evolution, the ranges of stellar masses leading to core-collapse and type Ia supernovae, and the antineutrino and neutrino backgrounds from core-collapse supernovae.

1,901 citations

Journal ArticleDOI
TL;DR: In this article, the authors give simple mass-matrices leading to tri-bimaximal mixing, and discuss its relation to the Fritzsch-Xing democratic ansatz.

1,347 citations