22 research outputs found
Momentum-dependent contributions to the gravitational coupling of neutrinos in a medium
When neutrinos travel through a normal matter medium, the electron neutrinos
couple differently to gravity compared to the other neutrinos, due to the
presence of electrons in the medium and the absence of the other charged
leptons. We calculate the momentum-dependent part of the matter-induced
gravitational couplings of the neutrinos under such conditions, which arise at
order , and determine their contribution to the neutrino dispersion
relation in the presence of a gravitational potential .
These new contributions vanish for the muon and tau neutrinos. For electron
neutrinos with momentum , they are of the order of the usual Wolfenstein
term times the factor , for high energy
neutrinos. In environments where the gravitational potential is substantial,
such as those in the vicinity of Active Galactic Nuclei, they could be the
dominant term in the neutrino dispersion relation. They must also be taken into
account in the analysis of possible violations of the Equivalence Principle in
the neutrino sector, in experimental settings involving high energy neutrinos
traveling through a matter background.Comment: Minor corrections in the references; one reference adde
Some Remarks on the Neutrino Oscillation Phase in a Gravitational Field
The weak gravitational field expansion method to account for the
gravitationally induced neutrino oscillation effect is critically examined. It
is shown that the splitting of the neutrino phase into a ``kinematic'' and a
``gravitational'' phase is not always possible because the relativistic factor
modifies the particle interference phase splitting condition in a gravitational
field.Comment: 4 pages, no figure
Critical Behavior of Dimensionally Continued Black Holes
The critical behavior of black holes in even and odd dimensional spacetimes
is studied based on Ba\~nados-Teitelboim-Zanelli (BTZ) dimensionally continued
black holes. In even dimensions it is found that asymptotically flat and anti
de-Sitter Reissner-Nordstr\"om black holes present up to two second order phase
transitions. The case of asymptotically anti-de-Sitter Schwarzschild black
holes present only one critical transition and a minimum of temperature, which
occurs at the transition. Finally, it is shown that phase transitions are
absent in odd dimensions.Comment: 21 pages in Latex format, no figures, vastly improved version to
appear in Phys. Rev.
The general treatment of high/low energy particle interference phase in a gravitational field
The interference phase of the high energy mass neutrinos and the low energy
thermal neutrons in a gravitational field are studied. For the mass neutrinos,
we obtain that the phase calculated along the null is equivalent to the half
phase along the geodesic in the high energy limit, which means that the correct
relative phase of the mass neutrinos is either the null phase or the half
geodesic phase.
Further we point out the importance of the energy condition in calculating
the mass neutrino interference phase. Moreover, we apply the covariant phase to
the calculation of the thermal neutron interference phase, and obtain the
consistent result with that exploited in COW experiment.Comment: 14 pages, 1 figur
Neutrino spin-flips in curved space-time
The general relativistic effects on spin-flavor oscillations above the core
of type II supernovae are investigated. The evolution equation is derived and
the relative magnitudes of the terms in the Hamiltonian, which arise from the
weak, electromagnetic and gravitational interaction, are compared. The effects
on the resonance position and the adiabaticity are studied. Explicit
calculations are presented for non-rotating and slowly rotating stars.Comment: 16 pages, 1 figure, accepted by Phys. Rev.
Neutrino oscillations in curved spacetime: an heuristic treatment
We discuss neutrino oscillations in curved spacetime. Our heuristic approach
can accomodate matter effects and gravitational contributions to neutrino spin
precession in the presence of a magnetic field. By way of illustration, we
perform explicit calculations in the Schwarzschild geometry. In this case,
gravitational effects on neutrino oscillations are intimately related to the
redshift. We discuss how spacetime curvature could affect the resonance
position and adiabaticity of matter-enhanced neutrino flavor conversion.Comment: 7 pages, REVTeX and 1 included style file. Submitted to Phys. Rev.
Interplay of Non-Relativistic and Relativistic Effects in Neutrino Oscillations
A theoretical structure that involves neutrino mass eigenstates at non
relativistic as well as relativistic energies is presented. Using this
framework, we find that if the particle X, with mass 33.9 MeV, of the KARMEN
collaboration anomaly is identified with the third neutrino mass eigenstate,
then the present limit of 23 MeV upper bound on the tau neutrino mass implies
|U_{\tau 3}| < 0.82.Comment: Revtex 3.0, 12 page
What makes a cyanobacterial bloom disappear? A review of the abiotic and biotic cyanobacterial bloom loss factors
Cyanobacterial blooms present substantial challenges to managers and threaten ecological and public health. Although the majority of cyanobacterial bloom research and management focuses on factors that control bloom initiation, duration, toxicity, and geographical extent, relatively little research focuses on the role of loss processes in blooms and how these processes are regulated. Here, we define a loss process in terms of population dynamics as any process that removes cells from a population, thereby decelerating or reducing the development and extent of blooms. We review abiotic (e.g., hydraulic flushing and oxidative stress/UV light) and biotic factors (e.g., allelopathic compounds, infections, grazing, and resting cells/programmed cell death) known to govern bloom loss. We found that the dominant loss processes depend on several system specific factors including cyanobacterial genera-specific traits, in situ physicochemical conditions, and the microbial, phytoplankton, and consumer community composition. We also address loss processes in the context of bloom management and discuss perspectives and challenges in predicting how a changing climate may directly and indirectly affect loss processes on blooms. A deeper understanding of bloom loss processes and their underlying mechanisms may help to mitigate the negative consequences of cyanobacterial blooms and improve current management strategies