926 research outputs found

    Present day status and future of nature conservation in the Republic of Malawi

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    When Malawi (formerly Nyasaland) became independent in 1964 the status and future of its game reserves were in jeopardy. The former administration had adopted a policy of benign neglect towards the country's wildlife areas (Anon 1963), and the remnants of the Department of Game, Fish and Tsetse Control had been absorbed by the Forestry Department in 1963. Fortunately the Life President of Malawi, Dr H Kamuzu Banda, took a strong interest in wildlife conservation and it was only his personal intervention, and the advent of independence, that saved the former Lengwe Game Reserve from deproclamation (Hayes 1967) as planned by the colonial administration. With the Life President's encouragement and the dedicated efforts of the staff responsible for wildlife, the tide which had been running strongly against nature conservation was turned, culminating in the establishment of a separate Department of National Parks and Wildlife only a decade after independence

    Carcass composition of the giraffe Giraffa camelopardalis giraffa

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    Connections between epsilon'/epsilon and Rare Kaon Decays in Supersymmetry

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    We analyze the rare kaon decays KLπ0ννˉK_L \to \pi^0 \nu \bar \nu, K+π+ννˉK^+ \to \pi^+ \nu \bar \nu, KLπ0e+eK_L \to \pi^0 e^+ e^- and KLμ+μK_L \to \mu^+ \mu^- in conjunction with the CP violating ratio ϵ/ϵ\epsilon'/\epsilon in a general class of supersymmetric models in which ZZ- and magnetic-penguin contributions can be substantially larger than in the Standard Model. We point out that radiative effects relate the double left-right mass insertion to the single left-left one, and that the phenomenological constraints on the latter reflect into a stringent bound on the supersymmetric contribution to the ZZ penguin. Using this bound, and those coming from recent data on ϵ/ϵ\epsilon'/\epsilon we find {\rm BR}(K_L \to \pi^0 \nu \bar \nu)\lsim 1.2\cdot 10^{-10}, {\rm BR}(K^+ \to \pi^+ \nu \bar \nu)\lsim 1.7\cdot 10^{-10}, {\rm BR}(K_L \to \pi^0 e^+ e^-)_{\rm dir}\lsim 2.0\cdot 10^{-11}, assuming the usual determination of the CKM parameters and neglecting the possibility of cancellations among different supersymmetric effects in ϵ/ϵ\epsilon'/\epsilon. Larger values are possible, in principle, but rather unlikely. We stress the importance of a measurement of these three branching ratios, together with improved data and improved theory of ϵ/ϵ\epsilon'/\epsilon, in order to shed light on the realization of various supersymmetric scenarios. We reemphasize that the most natural enhancement of ϵ/ϵ\epsilon'/\epsilon, within supersymmetric models, comes from chromomagnetic penguins and show that in this case sizable enhancements of BR(KLπ0e+e)dirBR(K_L \to \pi^0 e^+ e^-)_{\rm dir} can also be expected.Comment: 40 pages, 5 figure

    Supersymmetric models with minimal flavour violation and their running

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    We revisit the formulation of the principle of minimal flavor violation (MFV) in the minimal supersymmetric extension of the standard model, both at moderate and large tan(beta), and with or without new CP-violating phases. We introduce a counting rule which keeps track of the highly hierarchical structure of the Yukawa matrices. In this manner, we are able to control systematically which terms can be discarded in the soft SUSY breaking part of the Lagrangian. We argue that for the implementation of this counting rule, it is convenient to introduce a new basis of matrices in which both the squark (and slepton) mass terms as well as the trilinear couplings can be expanded. We derive the RGE for the MFV parameters and show that the beta functions also respect the counting rule. For moderate tan(beta), we provide explicit analytic solutions of these RGE and illustrate their behaviour by analyzing the neighbourhood (also switching on new phases) of the SPS-1a benchmark point. We then show that even in the case of large tan(beta), the RGE remain valid and that the analytic solutions obtained for moderate tan(beta) still allow us to understand the most important features of the running of the parameters, as illustrated with the help of the SPS-4 benchmark point.Comment: plain latex, 38 pages and 5 figures Eq. (12) corrected and one reference added, conclusions unchanged. Published versio

    Uplifted supersymmetric Higgs region

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    We show that the parameter space of the Minimal Supersymmetric Standard Model includes a region where the down-type fermion masses are generated by the loop-induced couplings to the up-type Higgs doublet. In this region the down-type Higgs doublet does not acquire a vacuum expectation value at tree level, and has sizable couplings in the superpotential to the tau leptons and bottom quarks. Besides a light standard-like Higgs boson, the Higgs spectrum includes the nearly degenerate states of a heavy spin-0 doublet which can be produced through their couplings to the bb quark and decay predominantly into \tau^+\tau^- or \tau\nu.Comment: 14 pages; Signs in Eqns. (3.1) and (4.2) corrected, appendix include

    Bottom-Tau Unification in SUSY SU(5) GUT and Constraints from b to s gamma and Muon g-2

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    An analysis is made on bottom-tau Yukawa unification in supersymmetric (SUSY) SU(5) grand unified theory (GUT) in the framework of minimal supergravity, in which the parameter space is restricted by some experimental constraints including Br(b to s gamma) and muon g-2. The bottom-tau unification can be accommodated to the measured branching ratio Br(b to s gamma) if superparticle masses are relatively heavy and higgsino mass parameter \mu is negative. On the other hand, if we take the latest muon g-2 data to require positive SUSY contributions, then wrong-sign threshold corrections at SUSY scale upset the Yukawa unification with more than 20 percent discrepancy. It has to be compensated by superheavy threshold corrections around the GUT scale, which constrains models of flavor in SUSY GUT. A pattern of the superparticle masses preferred by the three requirements is also commented.Comment: 21pages, 6figure

    Neutralino Dark Matter, b-tau Yukawa Unification and Non-Universal Sfermion Masses

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    We study the implications of minimal non-Universal Boundary Conditions in the sfermion Soft SUSY Breaking (SSB) masses of mSUGRA. We impose asymptotic b-tau Yukawa coupling Unification and we resort to a parameterization of the deviation from Universality in the SSB motivated by the multiplet structure of SU(5) GUT. A set of cosmo-phenomenological constraints, including the recent results from WMAP, determines the allowed parameter space of the models under consideration. We highlight a new coannihilation corridor where neutralino-sbottom and neutralino-tau sneutrino-stau coannihilations significantly contribute to the reduction of the neutralino relic density.Comment: 38 pages, 27 Figures, Latex; Version accepted for publication in PR
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