14 research outputs found
Resonant Spin-Flavor Conversion of Supernova Neutrinos and Deformation of the Electron Antineutrino Spectrum
The neutrino spin-flavor conversion of \bar\nu_e and \nu_\mu which is induced
by the interaction of the Majorana neutrino magnetic moment and magnetic fields
in the collapse-driven supernova is investigated in detail. We calculate the
conversion probability by using the latest precollapse models of Woosley and
Weaver (1995), and also those of Nomono and Hashimoto (1988), changing the
stellar mass and metallicity in order to estimate the effect of the
astrophysical uncertainties. Contour maps of the conversion probability are
given for all the models as a function of neutrino mass squared difference and
the neutrino magnetic moment times magnetic fields. It is shown that in the
solar metallicity models some observational effects are expected with \Delta
m^2 = 10^{-5}--10^{-1} [eV^2] and \mu_\nu >~ 10^{-12} (10^9 G / B_0) [\mu_B],
where B_0 is the strength of the magnetic fields at the surface of the iron
core. We also find that although the dependence on the stellar models or
stellar mass is not so large, the metallicity of precollapse stars has
considerable effects on this conversion. Such effects may be seen in a
supernova in the Large or Small Magellanic Clouds, and should be taken into
account when one considers an upper bound on \mu_\nu from the SN1987A data.Comment: 19 pages, LaTeX, using revtex. To appear in Phys. Rev. D. 16 figures
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Transition Economies in the Middle East: the Syrian Experience
There have been no in depth studies of post Socialist transition in the Middle East. Syriaâs experience is a useful one to explore given its historically important role in the region and its distinctive characteristics. The Syrian economic transition, from the early 1990s to 2011, was in two phases: an incremental liberalisation phase and a transition to Social Market Economy phase. During both phases, Syrian policy makers showed a preference for a gradualist approach to economic transition, rather than a big-bang approach. This was facilitated by oil revenues and subsidies from the Gulf States. The Syrian experience therefore has its own distinct characteristics, as well as elements in common with the transitions in other post Socialist economies
State and ethnicity in Botswana and Mauritius: A democratic route to development?
Botswana and Mauritius stand virtually alone among developing countries in having achieved rates of economic development rivalling those of the East Asian NICs, while maintaining democratic institutions. We compare their experiences with the goal of identifying aspects of a democratic route to development that avoids the inherent authoritarianism of the East Asian model. Our study is based upon Hyden's [1992] governance model, but we suggest two important modifications to that model. A strong state seems essential to achieving economic development, and we identify means of reducing the tendency for such states to lose accountability. Secondly, the experience of these two countries suggests ways in which the ethnic and tribal divisions that are so common in LDCs can be recognised by the state so that social pluralism makes a positive contribution to effective and democratic governance.