Fluorescence in ultraviolet active binaries: the case of FF Aquarii

The eclipsing binary FF Aquarii (FF Aqr) consists of a small hot star of uncertain type and a red giant. An Hα feature varies from absorption during eclipse to maximum emission during hot star transit. We have obtained simultaneous differential photometry in BVRI bands and Hα spectroscopy in 1998 that covered an entire orbit with some overlap. A binary star model was used with our light-curve, radial velocity and Hα data to refine stellar and orbital parameters. A new ephemeris indicates that the period has increased or is longer than previously thought. A physically simple algorithm is developed that generates properly blended spectral line profiles of binaries with arbitrary combinations of surface emission and absorption line regions. Although there is no radiative transfer, the algorithm can accommodate modest geometrical intricacy. For now, all line broadening in the model is rotational. The algorithm has now been incorporated within the general Wilson-Devinney binary star model, and we used it to model FF Aqr\u27s photospheric iron profile. It also is used to generate templates that illustrate problems with FF Aqr\u27s strongly time-dependent Hα emission profiles, which appear to be blends of features from the photosphere and from above the photosphere. The dominant broadening mechanism should be rotation for individual line components. Absorption profiles were generated by the model and fit to the observations to yield a red star radius ~6.9 Rsolar, which then requires i~ 76°. Our light-curve models have five spots with temperatures ~1000 K cooler than the surrounding photosphere. Hα emission was modelled on the red star surface, centred at the substellar point to simulate a fluorescent chromosphere. Additional emission is seen outside our modelled profiles. The origins of this excess emission may be corotating prominences, winds, or coronal mass ejections, all of which could affect the orbit period

Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos II. P-wave and next-to-next-to-leading order S-wave coefficients

This paper is a continuation of an earlier work (arXiv:1210.7928) which computed analytically the tree-level annihilation rates of a collection of non-relativistic neutralino and chargino two-particle states in the general MSSM. Here we extend the results by providing the next-to-next-to-leading order corrections to the rates in the non-relativistic expansion in momenta and mass differences, which include leading P-wave effects, in analytic form. The results are a necessary input for the calculation of the Sommerfeld-enhanced dark matter annihilation rates including short-distance corrections at next-to-next-to-leading order in the non-relativistic expansion in the general MSSM with neutralino LSP.Comment: LaTeX, 16 pages (+ 36 pages Appendix), 4 figures; v2 - new appendix with analytic results for the P-wave and rest of v^2 corrections to annihilation rates in the wino limit added, matches published versio

Solar Proton Transport within an ICRU Sphere Surrounded by a Complex Shield: Combinatorial Geometry

Citation: Wilson JW, Slaba TC, Badavi FF, Reddell BD, and Bahadori AA 2015 Solar Proton Transport within an ICRU Sphere Surrounded by a Complex Shield: Combinatorial Geometry NASA/TP-2015-218980 NASA Langley Research Center: Hampton, VA http://ntrs.nasa.gov/search.jsp?R=20160001628The 3DHZETRN code, with improved neutron and light ion (Z (is) less than 2) transport procedures, was recently developed and compared to Monte Carlo (MC) simulations using simplified spherical geometries. It was shown that 3DHZETRN agrees with the MC codes to the extent they agree with each other. In the present report, the 3DHZETRN code is extended to enable analysis in general combinatorial geometry. A more complex shielding structure with internal parts surrounding a tissue sphere is considered and compared against MC simulations. It is shown that even in the more complex geometry, 3DHZETRN agrees well with the MC codes and maintains a high degree of computational efficiency

Non-relativistic pair annihilation of nearly mass degenerate neutralinos and charginos I. General framework and S-wave annihilation

We compute analytically the tree-level annihilation rates of a collection of non-relativistic neutralino and chargino two-particle states in the general MSSM, including the previously unknown off-diagonal rates. The results are prerequisites to the calculation of the Sommerfeld enhancement in the MSSM, which will be presented in subsequent work. They can also be used to obtain concise analytic expressions for MSSM dark matter pair annihilation in the present Universe for a large number of exclusive two-particle final states.Comment: LATeX, 24 pages (+ 25 pages Appendix), 11 figures; v2 - replaced incorrect version of Fig. 4 and fixed typos listed in the JHEP erratu

A stress-controlled mechanism for the intensity of very large magnitude explosive eruptions

Large magnitude explosive eruptions are the result of the rapid and large-scale transport of silicic magma stored in the Earth's crust, but the mechanics of erupting teratonnes of silicic magma remain poorly understood. Here, we demonstrate that the combined effect of local crustal extension and magma chamber overpressure can sustain linear dyke-fed explosive eruptions with mass fluxes in excess of 10^10 kg/s from shallow-seated (4–6 km depth) chambers during moderate extensional stresses. Early eruption column collapse is facilitated with eruption duration of the order of few days with an intensity of at least one order of magnitude greater than the largest eruptions in the 20th century. The conditions explored in this study are one way in which high mass eruption rates can be achieved to feed large explosive eruptions. Our results corroborate geological and volcanological evidences from volcano-tectonic complexes such as the Sierra Madre Occidental (Mexico) and the Taupo Volcanic Zone (New Zealand)

On the anomalies in the latest LHCb data

Depending on the assumptions on the power corrections to the exclusive b -> s l+ l- decays, the latest data of the LHCb collaboration - based on the 3 fb^-1 data set and on two different experimental analysis methods - still shows some tensions with the SM predictions. We present a detailed analysis of the theoretical inputs and various global fits to all the available b -> s l+ l- data. This constitutes the first global analysis of the new data of the LHCb collaboration based on the hypothesis that these tensions can be at least partially explained by new physics contributions. In our model-independent analysis we present one-, two-, four-, and also five-dimensional global fits in the space of Wilson coefficients to all available b -> s l+ l- data. We also compare the two different experimental LHCb analyses of the angular observables in B -> K* mu+ mu-. We explicitly analyse the dependence of our results on the assumptions about power corrections, but also on the errors present in the form factor calculations. Moreover, based on our new global fits we present predictions for ratios of observables which may show a sign of lepton non-universality. Their measurements would crosscheck the LHCb result on the ratio R_K = BR(B+ -> K+ mu+ mu-) / BR(B+ -> K+ e+ e-) in the low-q^2 region which deviates from the SM prediction by 2.6 sigma.Comment: 41 pages, 24 figures. v2: references and comment on 1006.4945 [hep-ph] adde