331 research outputs found

    500 TeV gamma rays from Hercules X-1

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    A signal (chance probability = .0002) with the 1.24 s period of Hercules X-1 has been observed using the Utah Fly's Eye. The signal's relatively long period and high shower energy conflict with some popular models of particle acceleration by pulsars. Optical and X-ray data suggest a picture in which energetic particles produce multi-TeV gamma rays by collisions with Hercules X-1's accretion disk

    Pion Production from Baked-Alaska Disoriented Chiral Condensate

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    We study the various stages of the evolution of chiral condensates disoriented via the ``baked-alaska'' mechanism, in which the condensates are described as the products of external sources localized on the light cone. Our analysis is based on the classical equations of motion of either the linear or the nonlinear sigma model. We use the associated framework of coherent states and, especially, their source functions to make the connection to the distribution functions for the produced particles. We also compare our classical approach with a mean-field calculation which includes a certain class of quantum corrections.Comment: replaced to correct misspelling of author's nam

    Supersymmetric Electroweak Corrections to the Higgs Boson Decays into Chargino or Neutralino Pair

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    We investigate the supersymmetric electroweak corrections to the decay widths of the CP-odd and the heavy CP-even Higgs bosons into chargino or neutralino pair in the framework of the Minimal Supersymmetric Standard Model. The corrections involve the contributions of the order O(αewmt(b)3/mW3)O(\alpha_{ew} m_{t(b)}^3/m_W^3), O(αewmt(b)2/mW2)O(\alpha_{ew} m_{t(b)}^2/m_W^2) and O(αewmt(b)/mW)O(\alpha_{ew} m_{t(b)}/m_W). The detailed calculations of the electroweak corrections to the following decay processes: A0/H0→χ~1+χ~1−A^0/H^0 \to \tilde{\chi}^+_1 \tilde{\chi}^-_1 and A0/H0→χ~20χ~20A^0/H^0 \to \tilde{\chi}^0_2 \tilde{\chi}^0_2 are presented in this paper. We find that these relative corrections maybe rather large quantitatively, and can exceed 10% in some regions of parameter space. The corrections to the decay A0/H0→χ~10χ~20A^0/H^0 \to \tilde{\chi}^0_1 \tilde{\chi}^0_2 can be obtained analogously, but our results show that they are very small and can be neglected.Comment: 25 pages, 9 figures,accepted by Physical Review

    The SUSY EW-like corrections to top pair production in photon-photon collisions

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    We studied the one-loop contributions of the gaugino-Higgsino-sector to the process of top-pair production via γγ\gamma \gamma fusion at NLC in frame of the Minimal Supersymmetric Model(MSSM). We find that the corrections to γγ→ttˉ\gamma \gamma \to t\bar{t} and e+e−→γγ→ttˉe^+ e^- \to \gamma \gamma \to t\bar{t} are found to be significant and can approach to a few percent and one percent, respectively. Furthermore, the dependences of the corrections on the supersymmetric parameters are also investigated. The corrections are not sensitive to MSU(2)M_{SU(2)} (or âˆŁÎŒâˆŁ|\mu|) when MSU(2) >>Â âˆŁÎŒâˆŁM_{SU(2)}~>>~|\mu| (or âˆŁÎŒâˆŁÂ >> MSU(2)|\mu|~>>~M_{SU(2)}) and are weakly dependent on the tan⁥ÎČ\tan{\beta} with MQM_Q (or âˆŁÎŒâˆŁ|\mu|) being large enough. But they are sensitive to the c.m.s. energy of the incoming photons.Comment: LaTex, 33 pages, 8 Eps figuer

    Hadronic observables from SIS to SPS energies - anything strange with strangeness ?

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    We calculate p,π±,K±p, \pi^\pm, K^\pm and Λ\Lambda(+ÎŁ0\Sigma^0) rapidity distributions and compare to experimental data from SIS to SPS energies within the UrQMD and HSD transport approaches that are both based on string, quark, diquark (q,qˉ,qq,qˉqˉq, \bar{q}, qq, \bar{q}\bar{q}) and hadronic degrees of freedom. The two transport models do not include any explicit phase transition to a quark-gluon plasma (QGP). It is found that both approaches agree rather well with each other and with the experimental rapidity distributions for protons, Λ\Lambda's, π±\pi^\pm and K±K^\pm. Inspite of this apparent agreement both transport models fail to reproduce the maximum in the excitation function for the ratio K+/π+K^+/\pi^+ found experimentally between 11 and 40 A⋅\cdotGeV. A comparison to the various experimental data shows that this 'failure' is dominantly due to an insufficient description of pion rapidity distributions rather than missing 'strangeness'. The modest differences in the transport model results -- on the other hand -- can be attributed to different implementations of string formation and fragmentation, that are not sufficiently controlled by experimental data for the 'elementary' reactions in vacuum.Comment: 46 pages, including 15 eps figures, to be published in Phys. Rev.

    Electroweak Corrections to the Charged Higgs Boson Decay into Chargino and Neutralino

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    The electroweak corrections to the partial widths of the H+→χ~i+χ~j0(i=1,j=1,2)H^+ \to \tilde{\chi}^+_i \tilde{\chi}_j^0 (i=1,j=1,2) decays including one-loop diagrams of the third generation quarks and squarks, are investigated within the Supersymmetric Standard Model. The relative corrections can reach the values about 10%, therefore they should be taken into account for the precise experimental measurement at future colliders.Comment: 21 pages, 6 eps figures, 1 Latex fil

    Going Solo: findings from a survey of women ageing without a partner and who do not have children

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    Greater longevity in the UK population has led to the increasing diversity of women experiencing ageing in a multitude of ways. Internationally gender inequalities within ageing are still relatively invisible within both government policy and everyday life for particular groups of women. This paper explores the concept of women growing older ‘solo’ by which we mean women who find themselves non partnered and ageing without children as they move into later life. We report on the findings from a mixed-methods survey of 76 solo women in the UK aged 50 years and over, used to provide a broader overview of the issues and challenges they face as they move into later life. Qualitative data from the survey captured respondents’ perspectives about the links between their relationships status and wellbeing in later life and highlighted specific cumulative disadvantages emerging for some women as a result of their solo lifestyles. We discuss two key themes were identified; ‘solo-loneliness’ and ‘meaningful futures’ in conjunction with the relevant literature and make suggestions for future research within gender and ageing studies that could enhance more positive approaches to solo lifestyles

    Listening to the voices of women suffering perinatal psychological distress

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    This article suggests that transactional analysis can be an effective treatment approach for women suffering from mental health conditions and the emotional and life disturbances that may occur during the perinatal period. It offers a brief introduction to perinatal psychological distress followed by a description of the use of transactional analysis psychotherapy for this condition. The article outlines a new model for a research project that aims to ascertain women’s views on the helpfulness of the treatment and to gain a better understanding of the stigma often associated with perinatal mental health issues. The author argues for the necessity of qualitative research to assess the efficacy of transactional-analysis-based treatment and to increase our knowledge about the change process in transactional analysis psychotherapy with this client population as well as to inform future transactional analysis treatment protocols
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