6,339 research outputs found
Proposal to look for an up/down asymmetry in atmospheric neutrinos beyond Multi-GeV region with existing experimental data
We discuss a possible test of neutrino oscillation hypothesis by proposing
the combined analysis of high energy atmospheric neutrino induced muon events
that have been detected around horizontal direction in the Kolar Gold Field
(KGF) underground site and below the horizontal direction by many large
detectors such as Super-Kamiokande and MACRO. Up/down asymmetry obtained using
contained events recorded by detectors at Kamioka site probes low energy region
of atmospheric neutrino whereas, the suggested method probes high energy
neutrinos. It mainly depends on the observations and it is free of
uncertainties in neutrino flux, interaction cross section etc. In this paper we
demonstrate that the method is sensitive to a region of oscillation parameter
space that explains all the features of atmospheric neutrino data in the
Super-Kamiokande detector; the limiting factor being the statistical strength
of the KGF observations. This method provides the only way to study the up/down
asymmetry beyond Multi-GeV region which is yet to be measured experimentally.Comment: revtex, 6 pages with 3 eps figures. Error introduced by the different
low-energy thresholds assessed, conclusion unchange
Origin of Drastic Change of Fermi Surface and Transport Anomalies in CeRhIn5 under Pressure
The mechanism of drastic change of Fermi surfaces as well as transport
anomalies near P=Pc=2.35 GPa in CeRhIn5 is explained theoretically. The key
mechanism is pointed out to be the interplay of magnetic order and Ce-valence
fluctuations. We show that the antiferromagnetic state with "small" Fermi
surfaces changes to the paramagnetic state with "large" Fermi surfaces with
huge enhancement of effective mass of electrons with keeping finite c-f
hybridization. This explains the drastic change of the de Haas-van Alphen
signals. Furthermore, it is also consistent with the emergence of T-linear
resistivity simultaneous with the residual resistivity peak at P=Pc in CeRhIn5.Comment: 5 pages, 3 figures, submitted to Journal of Physical Society of Japa
Theory of Quasi-Universal Ratio of Seebeck Coefficient to Specific Heat in Zero-Temperature Limit in Correlated Metals
It is shown that the quasi-universal ratio of
the Seebeck coefficient to the specific heat in the limit of T=0 observed in a
series of strongly correlated metals can be understood on the basis of the
Fermi liquid theory description. In deriving this result, it is crucial that a
relevant scattering arises from impurities, but not from the mutual scattering
of quasiparticles. The systematics of the sign of is shown to reflect the
sign of the logarithmic derivative of the density of states and the inverse
mass tensor of the quasiparticles, explaining the systematics of experiments.
In particular, the positive sign of for Ce-based and -based heavy
fermions, and the negative sign for Yb-based and -based heavy fermions,
are explained. The case of non-Fermi liquid near the quantum critical point
(QCP) is briefly mentioned, showing that the ratio decreases considerably
toward antiferromagnetic QCP while it remains essentially unchanged for the
ferromagnetic QCP or QCP due to a local criticality.Comment: 12 pages, 1 figur
High-pressure study on the superconducting pyrochlore oxide Cd2Re2O7
Superconducting and structural phase transitions in a pyrochlore oxide
Cd2Re2O7 are studied under high pressure by x-ray diffraction and electrical
resistivity measurements. A rich P-T phase diagram is obtained, which contains
at least two phases with the ideal and slightly distorted pyrochlore
structures. It is found that the transition between them is suppressed with
increasing pressure and finally disappears at a critical pressure Pc = 3.5 GPa.
Remarkable enhancements in the residual resistivity as well as the coefficient
A of the AT 2 term in the resistivity are found around the critical pressure.
Superconductivity is detected only for the phase with the structural
distortion. It is suggested that the charge fluctuations of Re ions play a
crucial role in determining the electronic properties of Cd2Re2O7.Comment: 5 pages, 5 figures, submitted to J. Phys. Soc. Jp
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