1,011 research outputs found
Construction and analysis of a simplified many-body neutrino model
In dense neutrino systems, such as found in the early Universe, or near a
supernova core, neutrino flavor evolution is affected by coherent
neutrino-neutrino scattering. It has been recently suggested that many-particle
quantum entanglement effects may play an essential role in these systems,
potentially invalidating the traditional description in terms of a set of
single-particle evolution equations. We model the neutrino system by a system
of interacting spins, following an earlier work which showed that such a spin
system can in some cases be solved exactly. We extend this work by constructing
an exact analytical solution to a more general spin system, including initial
states with asymmetric spin distribution and, moreover, not necessarily aligned
along the same axis. Our solution exhibits a rich set of behaviors, including
coherent oscillations and dephasing and a transition from the classical to
quantum regimes. We argue that the classical evolution of the spin system
captures the entire coherent behavior of the neutrino system, while the quantum
effects in the spin system capture some, but not all, of the neutrino
incoherent evolution. By comparing the spin and neutrino systems, we find no
evidence for the violation of the accepted one-body description, though the
argument involves some subtleties not appreciated before. The analysis in this
paper may apply to other two-state systems beyond the neutrino field.Comment: 22 pages, 7 figure
Probing large distance higher dimensional gravity from lensing data
The modifications induced in the standard weak-lensing formula if Newtonian
gravity differs from inverse square law at large distances are studied. The
possibility of putting bounds on the mass of gravitons from lensing data is
explored. A bound on graviton mass, esitmated to be about 100 Mpc is
obtained from analysis of some recent data on gravitational lensing.Comment: 6 pages, 1 figure, added reference
Analysis of the decay
In this paper we study the angular distribution of the rare B decay , which is expected to be observed soon. We use the
standard effective Hamiltonian approach, and use the form factors that have
already been estimated for the corresponding radiative decay . The additional form factors that come into play for the dileptonic
channel are estimated using the large energy effective theory (LEET), which
enables one to relate the additional form factors to the form factors for the
radiative mode. Our results provide, just like in the case of the
resonance, an opportunity for a straightforward comparison of the basic theory
with experimental results which may be expected in the near future for this
channel.Comment: 14 pages, 5 figures; as accepted for Phys. Rev.
Non-Boltzmann behaviour in models of interacting neutrinos
We reconsider the question of the relative importance of single particle
effects and correlations in the solvable interacting neutrino models introduced
by Friedland and Lunardini and by Bell, Rawlinson and Sawyer. We show, by an
exact calculation, that the two particle correlations are not "small", and that
they dominate the time evolution in these models, in spite of indications to
the contrary from the rate of equilibration. This result holds even after the
model in generalized from the original 2 flavor case to flavors. The
failure of the Boltzmann single particle approximation in this model is
tentatively attributed to the simplicity of the model, in particular to the
assumption that all neutrinos in the initial state are in flavor eigenstates.Comment: 8 pages, 4 figure
MSW-like Enhancements without Matter
We study the effects of a scalar field, coupled only to neutrinos, on
oscillations among weak interaction current eigenstates. The effect of a real
scalar field appears as effective masses for the neutrino mass eigenstates, the
same for \nbar as for \n. Under some conditions, this can lead to a
vanishing of , giving rise to MSW-like effects. We discuss some
examples and show that it is possible to resolve the apparent discrepancy in
spectra required by r-process nucleosynthesis in the mantles of supernovae and
by Solar neutrino solutions.Comment: 9 pages, latex, 1 figur
Multichannel oscillations and relations between LSND, KARMEN and MiniBooNE, with and without CP violation
We show by examples that multichannel mixing can affect both the parameters
extracted from neutrino oscillation experiments, and that more general
conclusions derived by fitting the experimental data under the assumption that
only two channels are involved in the mixing. Implications for MiniBooNE are
noted and an example based on maximal CP violation displays profound
implications for the two data sets (muon-neutrino and muon-antineutrino) of
that experiment.Comment: 5 pages 4 figure
Introducing Novitates Paleoentomologicae: An outlet for occasional fossil insect research at the University of Kansas
This is the publisher's version, also available electronically from https://journals.ku.edu/index.php/paleoent/indexA new journal is introduced which disseminates the results of research conducted at or in association with the University of Kansas on fossil insects and their relatives. The journal spans all aspects of paleoentomological research, extending beyond systematic studies to include works on insect-bearing deposits, and their taphonomy and ecology
A fossil species of the primitive mymarid genus Borneomymar (Hymenoptera: Mymaridae) in Eocene Baltic amber
This is the publisher's version, also available electronically from https://journals.ku.edu/index.php/paleoent/article/view/4651A new fossil species of fairyfly (Hymenoptera: Chalcidoidea: Mymaridae) is described and figured from a well-preserved female in middle Eocene (Lutetian) Baltic amber as Borneomymar pankowskiorum Engel, McKellar, & Huber, new species. This species represents the fourth genus from Baltic amber whose extant species now occur only in southeastern Asia, Australia and Madagasca
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