Cosmological limits on neutrino masses are softened, by more than a factor 2, if Cold Dark Matter (CDM) and Dark Energy (DE) are coupled. In turn, a neutrino mass yielding $Ω_ν$ up to $\sim0.20$ allows coupling levels $β\simeq 0.15, $ or more, already easing the coincidence problem. The coupling, in fact, displaces both $P(k)$ and $C_l$ spectra in a fashion opposite to neutrino mass. Estimates are obtained through a Fisher--matrix technique.
This talk review status and results from the two presently operating underwater/ice neutrino telescopes, NT-200 in Lake Baikal and Amanda-II at the South Pole. It also gives a description of the design and the expected performance of Icecube, the next-generation neutrino telescope at South Pole.
The r-process in a low temperature environment is explored, in which the neutron emission by photodisintegration does not play a role (cold r-process). A semi-analytic neutrino-driven wind model is utilized for this purpose. The temperature in a supersonically expanding outflow can quickly drop to a few 10^8 K, where the (n, gamma)-(gamma, n) equilibrium is never achieved during the heavy r-nuclei synthesis. In addition, the neutron capture competes with the beta-decay owing to the low matter density. Despite such non-standard physical conditions for the cold r-process, a solar-like r-process …
The primary motivation for building neutrino telescopes is to open the road for neutrino astronomy, and to offer another observational window for the study of cosmic ray origins. Other physics topics, such as the search for WIMPs, can also be developed with neutrino telescope. As of March 2008, the IceCube detector, with half of its strings deployed, is the world largest neutrino telescope taking data to date and it will reach its completion in 2011. Data taken with the growing detector are being analyzed. The results of some of these works are summarized here. AMANDA has been successfully int…
We investigate the composition and the equation of state of the kaon condensed phase in neutrino-free and neutrino-trapped star matter within the framework of the Brueckner-Hartree-Fock approach with three-body forces. We find that neutrino trapping shifts the onset density of kaon condensation to a larger baryon density, and reduces considerably the kaon abundance. As a consequence, when kaons are allowed, the equation of state of neutrino-trapped star matter becomes stiffer than the one of neutrino free matter. The effects of different three-body forces are compared and discussed. Neutrino t…
We develop a method based on the collisionless Boltzmann equation to calculate the gravitational clustering of relic neutrinos in realistic cosmological models dominated by cold dark matter (CDM) and the cosmological constant. This method can be used to estimate the phase-space distribution of any light particles in CDM halos. We find that neutrinos with masses > 0.3 eV cluster appreciably in dark matter halos above the galactic size. The resulting neutrino overdensity above the cosmic mean neutrino density increases with both the neutrino mass and the halo mass, ranging from about 10 for 0.3 …
The bulk of recent cosmological research has focused on the adiabatic cold dark matter model and its simple extensions. Here we present an accurate fitting formula that describes the matter transfer functions of all common variants, including mixed dark matter models. The result is a function of wavenumber, time, and six cosmological parameters: the massive neutrino density, number of neutrino species degenerate in mass, baryon density, Hubble constant, cosmological constant, and spatial curvature. We show how observational constraints---e.g. the shape of the power spectrum, the abundance of c…
GENIUS is a proposal for a large volume detector to search for rare events. An array of 40-400 'naked' HPGe detectors will be operated in a tank filled with ultra-pure liquid nitrogen. After a description of performed technical studies of detector operation in liquid nitrogen and of Monte Carlo simulations of expected background components, the potential of GENIUS for detecting WIMP dark matter, the neutrinoless double beta decay in 76-Ge and low-energy solar neutrinos is discussed.
We calculate the thermochemical equilibrium of the diffuse interstellar medium, including ionization by a photon flux F_{nu} from neutrino decay. The main heating mechanism considered is photoelectrons from grains and PAHs. For the studied range of F_{nu} values, there always exists two regions of stability (a warm and a cold phase) that can coexist in equilibrium if the thermal interstellar pressure is between a maximum value P_{max} and a minimum value P_{min}. High F_{nu} values (~10^4-10^5 cm^{-2} s^{-1}) can be consistent with observed interstellar pressures only if more efficient sources…
Search for ultra high-energy neutrino induced reactions, as part of a comprehensive probe of the neutrino sky and also investigation of the particle nature of the dark matter, with unique sensitivity to cold dark matter particles are described. We present a description of the design, scientific motivation and goals, performance and status of the IceCube experiment.
我们报告的结果，从高分辨率的粒子网格（PM）N体模拟的结构形成的$Ω=1$宇宙学模型与冷加热暗物质（C+HDM）的混合物具有$Ω_{\rm cold}=0.6$，$Ω_ν=0.3$，和$Ω_{\rm baryon}=0.1$。我们提出了解析拟合的C+HDM功率谱的冷和热（$ν$）组件，这为我们的非线性模拟提供了初始条件。为了对中微子速度进行充分采样，这些模拟包括了6倍于冷粒子的中微子粒子。我们的模拟箱是14，50和200~Mpc立方体（$H_0=50$ km s $^{-1}$ Mpc $^{-1}$）;我们还在50~Mpc箱中对冷暗物质（CDM）进行了比较模拟。具有线性偏置因子$b=1.5$的C+HDM与COBE数据和我们计算的星系关联都是一致的。在我们的模拟中，我们发现晕的数量是质量和红移的函数;我们对CDM和C+HDM的结果与Press-Schechter模型吻合得很好。星系质量晕的数密度比CDM小，特别是在红移$z>2$处，但星系团质量晕的数量相当。我们还发现，在星系尺度上，C+HDM中的中微子速度和平坦的功率谱导致星系成对速度与数据符合得很好，并且在相同的偏置因子下比CDM中的速度小30%左右。在几十Mpc的尺度上，C+HDM流速度比CDM大得多。因此，C+HDM看起来很有希望作为结构形成的模型。
The recent atmospheric neutrino data from Super-Kamiokande provide strong evidence of neutrino oscillations and therefore of non-zero neutrino mass. These data imply a lower limit on the hot dark matter (i.e., light neutrino) contribution to the cosmological density $Ω_ν>~ 0.001$ --- almost as much as that of all the stars in the universe --- and permit higher $Ω_ν$. The ``standard'' COBE-normalized critical-matter-density (i.e., $Ω_m=1$) Cold Dark Matter (CDM) model has too much power on small scales. But adding to CDM neutrinos with mass of about 5 eV, corresponding to $Ω_ν\approx 0.2$, resu…
As experimentalists step up their pursuit of cold dark matter particles and neutrino masses, cosmological constraints are tightening. We compute the joint constraints on 11 cosmological parameters from cosmic microwave background and large scale structure data, and find that at 95% confidence, the total (cold+hot) dark matter density is h^2 Omega_dark = 0.20 +.12 -.10 with at most 38% of it being hot (due to neutrinos). A few assumptions, including negligible neutrinos, tighten this measurement to h^2 Omega_dark = 0.13 +0.04 -0.02, i.e, 2.4e-27 kg/m^3 give or take 20%.
We calculate with Monte Carlo the goodness of fit and the confidence level of the standard allowed regions for the neutrino oscillation parameters obtained from the fit of the total rates measured in solar neutrino experiments. We show that they are significantly overestimated in the standard method. We also calculate exact allowed regions with correct frequentist coverage. We show that the exact VO, LMA and LOW regions are much larger than the standard ones and merge together giving an allowed band at large mixing angles for all Delta m^2 > 10^{-10} eV^2.
We determine the three-neutrino mixing and mass parameters that are allowed by the solar and atmospheric neutrino data when vacuum oscillations are responsible for both phenomena. The global fit does not appreciably change the allowed regions for the parameters obtained from effective two-neutrino fits. We discuss how measurements of the solar electron energy spectrum below 6.5 GeV in Super-Kamiokande and seasonal variations in the Super-Kamiokande, $^{71}$Ga, and BOREXINO experiments can distinguish the different solar vacuum solutions.
We consider supersymmetric models with right-handed neutrinos where neutrino masses are purely Dirac-type. In this model, right-handed sneutrino can be the lightest supersymmetric particle and can be a viable candidate of cold dark matter of the universe. Right-handed sneutrinos are never thermalized in the early universe because of weakness of Yukawa interaction, but are effectively produced by decays of various superparticles. We show that the present mass density of right-handed sneutrino can be consistent with the observed dark matter density.
We analyze the existing solar neutrino experiment data and show the allowed regions. The result from SNO's salt phase itself restricts quite a lot the allowed region's area. Reactor neutrinos play an important role in determining oscillation parameters. KamLAND gives decisive conclusion on the solution to the solar neutrino puzzle, in particular, the spectral distortion in the 766.3 Ty KamLAND data gives another new improvement in the constraint of solar MSW-LMA solutions. We confirm that at 99.73% C.L. the high-LMA solution is excluded.
We calculate the incoherent resonant and non-resonant scattering production of sterile neutrinos in the early universe. We find ranges of sterile neutrino masses, vacuum mixing angles, and initial lepton numbers which allow these species to constitute viable hot, warm, and cold dark matter (HDM, WDM, CDM) candidates which meet observational constraints. The constraints considered here include energy loss in core collapse supernovae, energy density limits at big bang nucleosynthesis, and those stemming from sterile neutrino decay: limits from observed cosmic microwave background anisotropies, d…
We present constraints on the mass of warm dark matter (WDM) particles derived from the Lyman-alpha flux power spectrum of 55 high- resolution HIRES spectra at 2.0 < z < 6.4. From the HIRES spectra, we obtain a lower limit of mwdm > 1.2 keV 2 sigma if the WDM consists of early decoupled thermal relics and mwdm > 5.6 keV (2 sigma) for sterile neutrinos. Adding the Sloan Digital Sky Survey Lyman-alpha flux power spectrum, we get mwdm > 4 keV and mwdm > 28 keV (2 sigma) for thermal relics and sterile neutrinos. These results improve previous constraints by a factor two.
For active and sterile neutrinos, we present the globally allowed solutions for two neutrino oscillations. We include the SNO CC measurement and all other relevant solar neutrino and reactor data. Five active neutrino oscillation solutions (LMA, LOW, SMA, VAC, and Just So2) are currently allowed at 3 sigma; three sterile neutrino solutions (Just So2, SMA, and VAC) are allowed at 3 sigma. The goodness of fit is satisfactory for all eight solutions. We also investigate the robustness of the allowed solutions by carrying out global analyses with and without: 1) imposing solar model constraints on…
We examine the solar neutrino problem in the context of the realistic three neutrino mixing scenario including the SNO charged current (CC) rate. The two independent mass squared differences $Δm^2_{21}$ and $Δm^2_{31} \approx Δm^2_{32}$ are taken to be in the solar and atmospheric ranges respectively. We incorporate the constraints on $Δ$m$^2_{31}$ as obtained by the SuperKamiokande atmospheric neutrino data and determine the allowed values of $Δm^2_{21}$, $θ_{12}$ and $θ_{13}$ from a combined analysis of solar and CHOOZ data. Our aim is to probe the changes in the values of the mass and mixin…
The first results from the KamLAND experiment have provided confirmational evidence for the Large Mixing Angle (LMA) MSW solution to the solar neutrino problem. We do a global analysis of solar and the recently announced KamLAND data (both rate and spectrum) and investigate its effect on the allowed region in the $Δm^2-\tan^2θ$ plane. The best-fit from a combined analysis which uses the KamLAND rate plus global solar data comes at $Δm^2 = 6.06 \times 10^{-5}$ eV $^2$ and $\tan^2θ=0.42$, very close to the global solar best-fit, leaving a large allowed region within the global solar LMA contour.…
We consider the minimal supersymmetric standard model (MSSM) extended by introducing three right-handed (s)neutrinos to account for neutrino masses in the oscillation experiments. Assuming that the neutrino masses are purely Dirac-type, the lightest right-handed sneutrino $\tilde ν_R$ can be the lightest superparticle (LSP), which is a good candidate of cold dark matter (CDM) of the universe. We study the possibility of realizing $\tilde ν_R$-CDM, paying a special attention to the production of $\tilde ν_R$ via decay of the next-to-lightest superparticle (NLSP) after its freeze-out time. It is…
We discuss a simple approach to solve the transport equation for high-energy neutrinos in media of any thickness. We present illustrative results obtained with some specific models for the initial spectra of muon neutrinos and antineutrinos propagating through a normal cold medium.
We determine the range of neutrino masses and cosmic radiation content allowed by the most recent CMB and large-scale structure data. In contrast to other recent works, we vary these parameters simultaneously and provide likelihood contours in the two-dimensional parameter space of N_eff}, the usual effective number of neutrino species measuring the radiation density, and \sum m_nu. The allowed range of \sum m_nu and N_eff has shrunk significantly compared to previous studies. The previous degeneracy between these parameters has disappeared, largely thanks to the baryon acoustic oscillation da…
We present an analysis of the MSW neutrino oscillation solutions of the solar neutrino problem in the framework of two-neutrino mixing in the enlarged parameter space $(Δm^2, \tan^2θ)$ with $θ\in (0,\fracπ{2})$. Recently, it was pointed out that the allowed region of parameters from a fit to the measured total rates can extend to values $θ\geq \fracπ{4}$ (the so called ``dark side'') when higher confidence levels are allowed. The purpose of this letter is to reanalize the problem including all the solar neutrino data available, to discuss the dependence on the statistical criteria in the deter…
We compare, using a three neutrino analysis, the allowed neutrino oscillation parameters and solar neutrino fluxes determined by the experimental data available Before and After Neutrino 2004. New data available after Neutrino2004 include refined KamLAND and gallium measurements. We use six different approaches to analyzing the KamLAND data. We present detailed results using all the available neutrino and anti-neutrino data for Delta m^2_{12}, tan^2 theta_{12}, sin^2 theta_{13}, and sin^2 eta (sterile fraction). Using the same complete data sets, we also present Before and After determinations…
We present a global analysis of all the available solar neutrino data treating consistently the 8B and hep neutrino fluxes as free parameters. The analysis reveals at 99.7% C.L. eight currently-allowed discrete regions in two-neutrino oscillation space, five regions corresponding to active neutrinos and three corresponding to sterile neutrinos. Most of the allowed solutions are robust with respect to changes in the analysis procedure, but the traditional vacuum solution is fragile. The globally-permitted range of the 8B neutrino flux, 0.45 to 1.95 in units of the BP2000 flux, is comparable to …
The problem of the magnitude of the S--factor of the hep process $p + {^3\mathrm{He}} \to {^4\mathrm{He}} + e^+ + ν_e$ is one of the most important unsolved problems in nuclear astrophysics. The magnitude of $S(hep)$ has also an important impact on the interpretation of the Super-Kamiokande solar neutrino results in terms of neutrino oscillations. We point out the possiblity to determine the major hadronic contribution to $S(hep)$ from the measurement of the total cross section of the process $n + {^3\mathrm{H}} \to {^4\mathrm{He}} + e^- + \barν_e$ in experiments with high intensity beams of t…
We study the stability of the results of 3-nu oscillation analysis of atmospheric and reactor neutrino data under departures of the one--dominant mass scale approximation. In order to do so we perform the analysis of atmospheric and reactor neutrino data in terms of three--neutrino oscillations where the effect of both mass differences is explicitly considered. We study the allowed parameter space resulting from this analysis as a function of the mass splitting hierarchy parameter alpha = Delta m^2/Delta M^2 which parametrizes the departure from the one--dominant mass scale approximation. We c…
It is shown that the 99% confidence limits from the analyses of the data of cosmological and neutrino experiments imply a small marginally allowed region in the space of the neutrino oscillation parameters of 3+1 four-neutrino mixing schemes. This region can be confirmed or falsified by experiments in the near future.
