674 research outputs found

### Resolving Neutrino Mass Hierarchy and CP Degeneracy by Two Identical Detectors with Different Baselines

We explore the possibility of simultaneous determination of neutrino mass
hierarchy and the CP violating phase by using two identical detectors placed at
different baseline distances. We focus on a possible experimental setup using
neutrino beam from J-PARC facility in Japan with beam power of 4MW and megaton
(Mton)-class water Cherenkov detectors, one placed in Kamioka and the other at
somewhere in Korea. We demonstrate, under reasonable assumptions of systematic
uncertainties, that the two-detector complex with each fiducial volume of 0.27
Mton has potential of resolving neutrino mass hierarchy up to sin^2 2theta_{13}
> 0.03 (0.055) at 2\sigma (3\sigma) CL for any values of delta and at the same
time has the sensitivity to CP violation by 4 + 4 years running of nu_e and
nu_e-bar appearance measurement. The significantly enhanced sensitivity is due
to clean detection of modulation of neutrino energy spectrum, which is enabled
by cancellation of systematic uncertainties between two identical detectors
which receive the neutrino beam with the same energy spectrum in the absence of
oscillations.Comment: 23 pages, 10 figures, version published in PR

### Large-N Collective Field Theory Applied to Anyons in Magnetic Fields

We present a large-$N$ collective field formalism for anyons in external
magnetic fields interacting with arbitrary two-body potential. We discuss how
the Landau level is reproduced in our framework. We apply it to the soluble
model for anyons proposed by Girvin et al., and obtain the dispersion relation
of collective modes for arbitrary statistical parameters.Comment: 10 pages(Plain TeX) TMUP-HEL-930

### Neutrino Properties, Cosmology

Review of neutrino properties; double beta decay; very high energy neutrinos;
leptogenesisComment: 10 pages, 3 figures; conference tal

### Neutrino Velocity and Neutrino Oscillations

We study distances of propagation and the group velocities of the muon
neutrinos in the presence of mixing and oscillations assuming that Lorentz
invariance holds. Oscillations lead to distortion of the $\nu_\mu$ wave packet
which, in turn, changes the group velocity and the distance $\nu_\mu$ travels.
We find that the change of the distance, $d_{osc}$, is proportional to the
length of the wave packet, $\sigma_x$, and the oscillation phase, $\phi_p$,
acquired by neutrinos in the $\pi-$ and $K-$ meson decay tunnel where neutrino
wave packet is formed: $d_{osc} \propto \sigma \phi_p$. Although the distance
$d_{osc}$ may effectively correspond to the superluminal motion, the effect is
too tiny ($\sim 10^{- 5}$ cm) to be reconciled with the OPERA result. We
analyze various possibilities to increase $d_{osc}$ and discuss experimental
setups in which $d_{osc}$ (corresponding to the superluminal motion) can reach
an observable value $\sim 1$ m.Comment: LaTeX, 24 pages, 1 eps figure, matches to the published versio

### Non-Central Heavy-Ion Collisions are the Place to Look for DCC

We give two reasons why we believe that non-central ultrarelativistic heavy
ion collisions are the place to look for the disoriented chiral condensates
(DCC). First, we argue that the most probable quench scenario for the formation
of DCC requires non-central collisions. Second, we show by numerical
simulations that strong electromagnetic fields of heavy ions can exert a
surprisingly large effect on the DCC domain formation through the chiral
anomaly. The effect again requires non-central collisions. Interestingly, the
result of simulations is consistent with the formation of correlated two
domains of the chiral condensate, which are aligned in space, perpendicular to
the scattering plane, but misaligned in isospin space.Comment: 4 pages (Latex), 3 embedded ps figures, espcrc1 style, talk given at
Quark Matter 97, December 97, Tsukuba, Japa

### Probing supernova physics with neutrino oscillations

We point out that solar neutrino oscillations with large mixing angle as
evidenced in current solar neutrino data have a strong impact on strategies for
diagnosing collapse-driven supernova (SN) through neutrino observations. Such
oscillations induce a significant deformation of the energy spectra of
neutrinos, thereby allowing us to obtain otherwise inaccessible features of SN
neutrino spectra. We demonstrate that one can determine temperatures and
luminosities of non-electron flavor neutrinos by observing bar{nu}_{e} from
galactic SN in massive water Cherenkov detectors by the charged current
reactions on protons.Comment: 6 pages. Typos corrected and references added. Version to be
published in Physics Letters

### Large-Theta(13) Perturbation Theory of Neutrino Oscillation for Long-Baseline Experiments

The Cervera et al. formula, the best known approximate formula of neutrino
oscillation probability for long-baseline experiments, can be regarded as a
second-order perturbative formula with small expansion parameter epsilon \equiv
Delta m^2_{21} / Delta m^2_{31} \simeq 0.03 under the assumption s_{13} \simeq
epsilon. If theta_{13} is large, as suggested by a candidate nu_{e} event at
T2K as well as the recent global analyses, higher order corrections of s_{13}
to the formula would be needed for better accuracy. We compute the corrections
systematically by formulating a perturbative framework by taking theta_{13} as
s_{13} \sim \sqrt{epsilon} \simeq 0.18, which guarantees its validity in a wide
range of theta_{13} below the Chooz limit. We show on general ground that the
correction terms must be of order epsilon^2. Yet, they nicely fill the mismatch
between the approximate and the exact formulas at low energies and relatively
long baselines. General theorems are derived which serve for better
understanding of delta-dependence of the oscillation probability. Some
interesting implications of the large theta_{13} hypothesis are discussed.Comment: Fig.2 added, 23 pages. Matches to the published versio

### Parameter Degeneracies in Neutrino Oscillation Measurement of Leptonic CP and T Violation

The measurement of the mixing angle \theta_{13}, sign of \Delta m^2_{13} and
the CP or T violating phase \delta is fraught with ambiguities in neutrino
oscillation. In this paper we give an analytic treatment of the paramater
degeneracies associated with measuring the \nu_\mu -> \nu_e probability and its
CP and/or T conjugates. For CP violation, we give explicit solutions to allow
us to obtain the regions where there exist two-fold and four-fold degeneracies.
We calculate the fractional differences, \Delta \theta / \bar{\theta}, between
the allowed solutions which may be used to compare with the expected
sensitivities of the experiments. For T violation we show that there is always
a complete degeneracy between solutions with positive and negative \Delta
m^2_{13} which arises due to a symmetry and cannot be removed by observing one
neutrino oscillation probability and its T conjugate. Thus, there is always a
four fold parameter degeneracy apart from exceptional points. Explicit
solutions are also given and the fractional differences are computed. The
bi-probability CP/T trajectory diagrams are extensively used to illuminate the
nature of the degeneracies.Comment: 35 pages, Latex, 11 postscript figures, minor correction

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