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 $\gamma\nu\to\gamma\gamma \nu$ 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 $\gamma\nu\to\gamma\gamma\nu$ and $\gamma\gamma\to\gamma{\nu}\bar\nu$ and show how to use the $\gamma\gamma\to\gamma\gamma$ results as a check. We settle the question of the disagreement between two computations in the literature concerning the reaction $\gamma\gamma\to \gamma \nu\bar\nu$. 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 $\gamma\nu\to\gamma\gamma \nu$ 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 $\gamma\nu\to\gamma\gamma\nu$ and $\gamma\gamma\to\gamma{\nu}\bar\nu$, give their polarized cross sections, and show how to use the $\gamma\gamma\to\gamma\gamma$ results as a check. We settle the question about the disagreement between two computations in the literature concerning the reaction $\gamma\gamma\to \gamma \nu\bar\nu$.Comment: 14 pages, RevTeX, axodraw, 3 figures, comment adde

SOS rule formats for convex and abstract probabilistic bisimulations

Probabilistic transition system specifications (PTSSs) in the $nt \mu f\theta / nt\mu x\theta$ 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 $nt \mu f\theta / nt\mu x\theta$ 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 $(g,G)$ of a continuous body, the tensor field $G$ is known to be a measure of deformations without disarrangements, and $M:=\nabla g-G$ is known to be a measure of deformations due to disarrangements. The tensor fields $G$ and $M$ together deliver not only standard notions of plastic deformation, but $M$ 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) $(trM)^{+}$, the positive part of $trM$, is a volume density of disarrangements due to submacroscopic separations, (2) $(trM)^{-}$, the negative part of $trM$, is a volume density of disarrangements due to submacroscopic switches and interpenetrations, and (3) $|trM|$, the absolute value of $trM$, 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 $(trM)^{+}$, $(trM)^{-}$, and $|trM|$ 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 $E$ and $B$ 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 $47^o$ degree ring. We will also consider another example, an experiment that measures one of the Stokes parameters in a $1^o$ 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 $Q$ and $U$ are measured, separate constraints can be set on $E$ and $B$ polarization.Comment: 27 pages with 12 included figure