Measuring the CP-violating phase by a long base-line neutrino experiment with Hyper-Kamiokande

We study the sensitivity of a long-base-line (LBL) experiment with neutrino beams from the High Intensity Proton Accelerator (HIPA), that delivers 10^{21} POT per year, and a proposed 1Mt water-Cherenkov detector, Hyper-Kamiokande (HK) 295km away from the HIPA, to the CP phase (delta_{M N S}) of the three-flavor lepton mixing matrix. We examine a combination of the nu_mu narrow-band beam (NBB) at two different energies, vev{p_pi}=2, 3GeV, and the bar{nu}_mu NBB at vev{p_pi}=2GeV. By allocating one year each for the two nu_mu beams and four years for the bar{nu}_mu beam, we can efficiently measure the nu_mu to nu_e and bar{nu}_mu to bar{nu}_e transition probabilities, as well as the nu_mu and bar{nu}_mu survival probabilities. CP violation in the lepton sector can be established at 4sigma (3sigma) level if the MSW large-mixing-angle scenario of the solar-neutrino deficit is realized, |\dmns| or |delta{M N S}-180^{circ}| > 30^{circ}, and if 4|U_{e3}|^2 (1-|U_{e3}|^2) equiv sin^2 2 theta_{CHOOZ} > 0.03 (0.01). The phase delta_{M N S} is more difficult to constrain by this experiment if there is little CP violation, delta_{M N S} sim 0^{circ} or 180^{circ}, which can be distinguished at 1sigma level if sin^2 2 theta_{CHOOZ} >~ 0.01.Comment: 16 pages, 4 figures, 2 tables, we add 1 figure, some refrences, and minor corrections. PLB published versio

Are lepton flavor mixings in the democratic mass matrix stable against quantum corrections?

We investigate whether the lepton flavor mixing angles in the so-called democratic type of mass matrix are stable against quantum corrections or not in the minimal supersymmetric standard model with dimension five operator which induces neutrino mass matrix. By taking simple breaking patterns of $S_3{}_L \times S_3{}_R$ or $O(3)_L \times O(3)_R$ flavor symmetries and the scale where democratic textures are induced as $O(10^{13})$ GeV, we find that the stability of the lepton flavor mixing angles in the democratic type of mass matrix against quantum corrections depends on the solar neutrino solutions. The maximal flavor mixing of the vacuum oscillation solution is spoiled by the quantum corrections in the experimental allowed region of $\tan \beta$. The large angle MSW solution is spoiled by the quantum corrections in the region of $\tan \beta > 10$. The condition of $\tan \beta \leq 10$ is needed in order to obtain the suitable mass squared difference of the small angle MSW solution. These strong constraints must be regarded for the model building of the democratic type of mass matrixComment: 12pages,LaTe

Novel vortex lattice transition in d-wave superconductors

We study the vortex state in a magnetic field parallel to the $c$ axis in the framework of the extended Ginzburg Landau equation. We find the vortex acquires a fourfold modulation proportional to $\cos(4\phi)$ where $\phi$ is the angle ${\bf r}$ makes with the $a$-axis. This term gives rise to an attractive interaction between two vortices when they are aligned parallel to $(1,1,0)$ or $(1,-1,0)$. We predict the first order vortex lattice transition at $B=H_{cr}\sim \kappa^{-1} H_{c2}(t)$ from triangular into the square lattice tilted by $45^\circ$ from the $a$ axis. This gives the critical field $H_{cr}$ a few Tesla for YBCO and Bi2212 monocrystals at low temperatures ($T\leq 10 K$).Comment: 6 pages, 4 figure

Detecting z > 10 objects through carbon, nitrogen and oxygen emission lines

By redshift of 10, star formation in the first objects should have produced considerable amounts of Carbon, Nitrogen and Oxygen. The submillimeter lines of C, N and O redshift into the millimeter and centimeter bands (0.5 mm -- 1.2 cm), where they may be detectable. High spectral resolution observations could potentially detect inhomogeneities in C, N and O emission, and see the first objects forming at high redshift. We calculate expected intensity fluctuations and discuss frequency and angular resolution required to detect them. For CII emission, we estimate the intensity using two independent methods: the line emission coefficient argument and the luminosity density argument. We find they are in good agreement. At 1+z \sim 10, the typical protogalaxy has a velocity dispersion of 30 km s^{-1} and angular size of 1 arcsecond. If CII is the dominant coolant, then we estimate a characteristic line strength of \sim 0.1 K km s^{-1}. We also discuss other atomic lines and estimate their signal. Observations with angular resolution of 10^{-3} can detect moderately nonlinear fluctuations of amplitude 2 \cdot 10^{-5} times the microwave background. If the intensity fluctuations are detected, they will probe matter density inhomogeneity, chemical evolution and ionization history at high redshifts.Comment: 15 pages, 1 postscript figures included; Uses aaspp4.sty (AASTeX v4.0); Submitted to The Astrophysical Journa

A question of hierarchy: matter effects with atmospheric neutrinos and anti-neutrinos

It is by now established that neutrinos mix, have (different) non-zero masses, and therefore oscillate. The oscillation parameters themselves, however, are not all well-known. An open problem is that of the neutrino mass hierarchy. We study the possibility of determining the neutrino mass hierarchy with atmospheric neutrinos using an iron calorimeter detector capable of charge identification such as the proposed MONOLITH and ICAL/INO detectors. We find that such detectors are sensitive to the sign of the mass-squared difference, \delta_{32} = m_3^2 - m_2^2, provided the as-yet unknown mixing angle between the first and third generations, \theta_{13}, is greater than 6 degrees (\sin^2 2\theta_{13} > 0.04). A result with a significance greater than 90% CL requires large exposures (more than 500 kton-years) as well as good energy and angular resolution of the detected muons (better than 15%), especially for small \theta_{13}. Hence obtaining definitive results with such a detector is difficult, unless \theta_{13} turns out to be large. In contrast, such detectors can establish a clear oscillation pattern in atmospheric neutrinos in about 150 kton-years, therefore determining the absolute value of \delta_{32} and \sin^2 2 \theta_{23} to within 10%.Comment: 36 pages revtex with 14 eps figures; new section on statistical significance when detector resolution is include

Charge current in ferromagnet - triplet superconductor junctions

We calculate the tunneling conductance spectra of a ferromagnetic metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor, we assume one special $p$-wave order parameter, having line nodes, and two two dimensional $f$-wave order parameters with line nodes, breaking the time reversal symmetry. Also we examine nodeless pairing potentials. The evolution of the spectra with the exchange potential depends solely on the topology of the gap. The weak Andreev reflection within the ferromagnet results in the suppression of the tunneling conductance and eliminates the resonances due to the anisotropy of the pairing potential. The tunneling spectra splits asymmetrically with respect to $E=0$ under the influence of an external magnetic field. The results can be used to distinguish between the possible candidate pairing states of the superconductor Sr$_2$RuO$_4$.Comment: 15 pages with 8 figure

Superconductivity in Geometrically Frustrated Pyrochlore RbOs2O6

We report the basic thermodynamic properties of the new geometrically frustrated beta-pyrochlore bulk superconductor RbOs2O6 with a critical temperature Tc = 6.4 K. Specific heat measurements are performed in magnetic fields up to 12 T. The electronic density of states at the Fermi level in the normal state results in gamma = (33.7 \pm 0.2) mJ/mol_f.u./K^2. In the superconducting state, the specific heat follows conventional BCS-type behavior down to 1 K, i.e. over three orders of magnitude in specific heat data. The upper critical field slope at Tc is 1.2 T/K, corresponding to a Maki-parameter alpha = 0.64 \pm 0.1. From the upper critical field mu0 Hc2 \approx 6 T at 0 K, we estimate a Ginzburg-Landau coherence length xi \approx 7.4 nm. RbOs2O6 is the second reported metallic AB2O6 type pyrochlore compound after KOs2O6, and one of only three pyrochlore superconductors in addition to Cd2Re2O7 and KOs2O6

Neutrinoless Double Beta Decay and Future Neutrino Oscillation Precision Experiments

We discuss to what extent future precision measurements of neutrino mixing observables will influence the information we can draw from a measurement of (or an improved limit on) neutrinoless double beta decay. Whereas the Delta m^2 corresponding to solar and atmospheric neutrino oscillations are expected to be known with good precision, the parameter theta_{12} will govern large part of the uncertainty. We focus in particular on the possibility of distinguishing the neutrino mass hierarchies and on setting a limit on the neutrino mass. We give the largest allowed values of the neutrino masses which allow to distinguish the normal from the inverted hierarchy. All aspects are discussed as a function of the uncertainty stemming from the involved nuclear matrix elements. The implications of a vanishing, or extremely small, effective mass are also investigated. By giving a large list of possible neutrino mass matrices and their predictions for the observables, we finally explore how a measurement of (or an improved limit on) neutrinoless double beta decay can help to identify the neutrino mass matrix if more precise values of the relevant parameters are known.Comment: 35 pages, 12 figures. Comments and references added. To appear in PR

Relation between the neutrino and quark mixing angles and grand unification

We argue that there exists simple relation between the quark and lepton mixings which supports the idea of grand unification and probes the underlying robust bi-maximal fermion mixing structure of still unknown flavor physics. In this framework the quark mixing matrix is a parameter matrix describing the deviation of neutrino mixing from exactly bi-maximal, predicting theta_{sol}+theta_C=pi/4, where theta_C is the Cabibbo angle, theta_{atm}+theta_{23}^{CKM}=pi/4 and theta_{13}^{MNS} ~ theta_{13}^{CKM} ~ O(lambda^3), in a perfect agreement with experimental data. Both non-Abelian and Abelian flavor symmetries are needed for such a prediction to be realistic. An example flavor model capable to explain this flavor mixing pattern, and to induce the measured quark and lepton masses, is outlined.Comment: references added, title changed in journa

X-Ray and Gamma-Ray Emission from the PSR 1259-63 / Be Star System

PSR 1259-63 is a radio pulsar orbiting a Be star in a highly eccentric orbit. Soft and hard X-rays are observed from this binary system. We apply the shock powered emission model to this system. The collision of the pulsar and Be star winds forms a shock, which accelerates electrons and positrons to the relativistic energies. We derive the energy distribution of relativistic electrons and positrons as a function of the distance from the shock in the pulsar nebula. We calculate the X-rays and $\gamma$-rays emitted from the relativistic electrons and positrons in the nebula at various orbital phases, taking into account the Klein-Nishina effect fully. The shock powered emission model can explain the observed X-ray properties approximately. We obtain from the comparison with observations that a fraction of $\sim 0.1$ of the pulsar spin-down luminosity should be transformed into the relativistic electrons and positrons. We find that the magnetization parameter of the pulsar wind, the ratio of the Poynting flux to the kinetic energy flux, is $\sim 0.1$ immediately upstream of the termination shock of the pulsar wind, and may decrease with distance from the pulsar. We predict the flux of 10 MeV - 100 GeV $\gamma$-rays which may be nearly equal to the detection threshold in the future projects.Comment: 18 pages, 9 figures, accepted for publication in PAS