4,251 research outputs found
Five-leg photon-neutrino interactions
In a first part, we justify the feasibility of substituting a photon leg by a
neutrino current in the Euler-Heisenberg Lagrangian to obtain an effective
Lagrangian for the process and its crossed
reactions.
We establish the link between these processes and the four-photon scattering
in both the Standard Model and the effective theory. As an application, we
compute in this effective theory the processes
and and show how to use the
results as a check. We settle the question of the
disagreement between two computations in the literature concerning the reaction
. In the second part, we present results of
the direct computation of the photon-neutrino five-leg processes in the
Standard Model, discuss possible astrophysical implications of our results, and
provide simple fits to the exact expressions.Comment: 6 pages, axodraw, ltwol2e, 5 figures, contributed paper to the 29th
International Conference on High Energy Physics (Vancouver
Inelastic photon-neutrino interactions using an effective Lagrangian
We justify the feasibility of substituting a photon leg by a neutrino current
in the Euler-Heisenberg Lagrangian to obtain an effective Lagrangian for the
process and its crossed reactions. We establish
the link between these processes and the four-photon scattering in both the
Standard Model and the effective theory. As an application, we compute the
processes and
, give their polarized cross sections, and
show how to use the results as a check. We settle
the question about the disagreement between two computations in the literature
concerning the reaction .Comment: 14 pages, RevTeX, axodraw, 3 figures, comment adde
Cuba’s Transition to a Free-Market Democracy: A Survey of Required Changes to Laws and Legal Institutions
SOS rule formats for convex and abstract probabilistic bisimulations
Probabilistic transition system specifications (PTSSs) in the format provide structural operational semantics for
Segala-type systems that exhibit both probabilistic and nondeterministic
behavior and guarantee that bisimilarity is a congruence for all operator
defined in such format. Starting from the
format, we obtain restricted formats that guarantee that three coarser
bisimulation equivalences are congruences. We focus on (i) Segala's variant of
bisimulation that considers combined transitions, which we call here "convex
bisimulation"; (ii) the bisimulation equivalence resulting from considering
Park & Milner's bisimulation on the usual stripped probabilistic transition
system (translated into a labelled transition system), which we call here
"probability obliterated bisimulation"; and (iii) a "probability abstracted
bisimulation", which, like bisimulation, preserves the structure of the
distributions but instead, it ignores the probability values. In addition, we
compare these bisimulation equivalences and provide a logic characterization
for each of them.Comment: In Proceedings EXPRESS/SOS 2015, arXiv:1508.0634
Gamma-ray absorption in the microquasar SS433
We discuss the gamma-ray absorption in the inner region of the microquasar
SS433. Our investigation includes several contributions to the opacity of this
system. They result from the ambient fields generated by the primary star,
possibly an A-type supergiant, and a very extended disk around the black hole.
Besides the sharp and dramatic absorption effect that occurs every time the
star crosses the emission zone, we find in the UV photon field from the
extended disk an important source of absorption for very high energy
gamma-rays. This results in periodic gamma-ray observational signatures.Comment: 8 pages, 9 figures, to appear in Astropart.Phy
Explicit Formulas for Relaxed Disarrangement Densities Arising from Structured Deformations
Structured deformations provide a multiscale geometry that captures the
contributions at the macrolevel of both smooth geometrical changes and
non-smooth geometrical changes (disarrangements) at submacroscopic levels. For
each (first-order) structured deformation of a continuous body, the
tensor field is known to be a measure of deformations without
disarrangements, and is known to be a measure of deformations
due to disarrangements. The tensor fields and together deliver not only
standard notions of plastic deformation, but and its curl deliver the
Burgers vector field associated with closed curves in the body and the
dislocation density field used in describing geometrical changes in bodies with
defects. Recently, Owen and Paroni [13] evaluated explicitly some relaxed
energy densities arising in Choksi and Fonseca's energetics of structured
deformations [4] and thereby showed: (1) , the positive part of
, is a volume density of disarrangements due to submacroscopic
separations, (2) , the negative part of , is a volume density
of disarrangements due to submacroscopic switches and interpenetrations, and
(3) , the absolute value of , is a volume density of all three of
these non-tangential disarrangements: separations, switches, and
interpenetrations. The main contribution of the present research is to show
that a different approach to the energetics of structured deformations, that
due to Ba\'ia, Matias, and Santos [1], confirms the roles of ,
, and established by Owen and Paroni. In doing so, we give
an alternative, shorter proof of Owen and Paroni's results, and we establish
additional explicit formulas for other measures of disarrangements.Comment: 17 pages; http://cvgmt.sns.it/paper/2776
Lensing reconstruction of cluster-mass cross-correlation with cosmic microwave background polarization
We extend our maximum likelihood method for reconstructing the cluster-mass
cross-correlation from cosmic microwave background (CMB) temperature
anisotropies and develop new estimators that utilize six different quadratic
combinations of CMB temperature and polarization fields. Our maximum likelihood
estimators are constructed with delensed CMB temperature and polarization
fields by using an assumed model of the convergence field and they can be
iteratively applied to a set of clusters, approaching to the optimal condition
for the lensing reconstruction as the assumed initial model is refined. Using
smoothed particle hydrodynamics simulations, we create a catalog of realistic
clusters obtainable from the current Sunyaev-Zel'dovich (SZ) surveys, and we
demonstrate the ability of the maximum likelihood estimators to reconstruct the
cluster-mass cross-correlation from the massive clusters. The iTT temperature
estimator provides a signal-to-noise ratio of a factor 3 larger than the iEB
polarization estimator, unless the detector noise for measuring polarization
anisotropies is controlled under 3 microK.Comment: 10 pages, 6 figures, accepted for publication in Physical Review
CMB Polarization Experiments
We discuss the analysis of polarization experiments with particular emphasis
on those that measure the Stokes parameters on a ring on the sky. We discuss
the ability of these experiments to separate the and contributions to
the polarization signal. The experiment being developed at Wisconsin university
is studied in detail, it will be sensitive to both Stokes parameters and will
concentrate on large scale polarization, scanning a degree ring. We will
also consider another example, an experiment that measures one of the Stokes
parameters in a ring. We find that the small ring experiment will be able
to detect cosmological polarization for some models consistent with the current
temperature anisotropy data, for reasonable integration times. In most
cosmological models large scale polarization is too small to be detected by the
Wisconsin experiment, but because both and are measured, separate
constraints can be set on and polarization.Comment: 27 pages with 12 included figure
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