10,756 research outputs found
Chaos, Determinacy and Fractals in Active-Sterile Neutrino Oscillations in the Early Universe
The possibility of light sterile neutrinos allows for the resonant production
of lepton number in the early universe through matter-affected neutrino mixing.
For a given a mixing of the active and sterile neutrino states it has been
found that the lepton number generation process is chaotic and strongly
oscillatory. We undertake a new study of this process' sensitivity to initial
conditions through the quantum rate equations. We confirm the chaoticity of the
process in this solution, and moreover find that the resultant lepton number
and the sign of the asymmetry produces a fractal in the parameter space of
mass, mixing angle and initial baryon number. This has implications for future
searches for sterile neutrinos, where arbitrary high sensitivity could not be
determinate in forecasting the lepton number of the universe.Comment: 6 pages, 3 figure
Bright gap solitons of atoms with repulsive interaction
We report on the first experimental observation of bright matter-wave
solitons for 87Rb atoms with repulsive atom-atom interaction. This counter
intuitive situation arises inside a weak periodic potential, where anomalous
dispersion can be realized at the Brillouin zone boundary. If the coherent
atomic wavepacket is prepared at the corresponding band edge a bright soliton
is formed inside the gap. The strength of our system is the precise control of
preparation and real time manipulation, allowing the systematic investigation
of gap solitons.Comment: 4 pages, 4 figure
Variational approach for walking solitons in birefringent fibres
We use the variational method to obtain approximate analytical expressions
for the stationary pulselike solutions in birefringent fibers when differences
in both phase velocities and group velocities between the two components and
rapidly oscillating terms are taken into account. After checking the validity
of the approximation we study how the soliton pulse shape depends on its
velocity and nonlinear propagation constant. By numerically solving the
propagation equation we have found that most of these stationary solutions are
stable.Comment: LaTeX2e, uses graphicx package, 23 pages with 8 figure
Study of Co-seismic Planetary Conditions for Earthquake Prediction
The periodicities in the occurrence of earthquakes, as indicated by the cosmic conditions, have been traced by analysing the planetary data at the time of occurrence of more than 1100 earthquakes of magnitude, M 27.0, which occurred during the period 1896 to 1965. Correlation between the transits of planets in the sensitive areas and at sensitive longitudes in the zodiac and the seismicity of California and adjoining area has been shown. Based on the analysis, a method for forecasting earthquakes is also proposed
Achievable Qubit Rates for Quantum Information Wires
Suppose Alice and Bob have access to two separated regions, respectively, of
a system of electrons moving in the presence of a regular one-dimensional
lattice of binding atoms. We consider the problem of communicating as much
quantum information, as measured by the qubit rate, through this quantum
information wire as possible. We describe a protocol whereby Alice and Bob can
achieve a qubit rate for these systems which is proportional to N^(-1/3) qubits
per unit time, where N is the number of lattice sites. Our protocol also
functions equally in the presence of interactions modelled via the t-J and
Hubbard models
Information content of the weak-charge form factor
Parity-violating electron scattering provides a model-independent
determination of the nuclear weak-charge form factor that has widespread
implications across such diverse areas as fundamental symmetries, nuclear
structure, heavy-ion collisions, and neutron-star structure. We assess the
impact of precise measurements of the weak-charge form factor of Ca
and Pb on a variety of nuclear observables, such as the neutron skin
and the electric-dipole polarizability. We use the nuclear Density Functional
Theory with several accurately calibrated non-relativistic and relativistic
energy density functionals. To assess the degree of correlation between nuclear
observables and to explore systematic and statistical uncertainties on
theoretical predictions, we employ the chi-square statistical covariance
technique. We find a strong correlation between the weak-charge form factor and
the neutron radius, that allows for an accurate determination of the neutron
skin of neutron-rich nuclei. We determine the optimal range of the momentum
transfer that maximizes the information content of the measured weak-charge
form factor and quantify the uncertainties associated with the strange quark
contribution. Moreover, we confirm the role of the electric-dipole
polarizability as a strong isovector indicator. Accurate measurements of the
weak-charge form factor of Ca and Pb will have a profound
impact on many aspects of nuclear theory and hadronic measurements of neutron
skins of exotic nuclei at radioactive-beam facilities.Comment: 10 pages, 4 figure
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