26,057 research outputs found

    Producing baryons from neutralinos in small H2 clumps over cosmological ages

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    Extreme scattering events in quasars suggest the existence of dark H2\rm H_2 clumps of mass 103M\rm \sim 10^{-3} M_\odot and size 10AU\rm \sim 10 AU. Such clumps are extremely dense compared to WIMPs clumps of the same mass obtained by N-body simulations. A WIMP clump gravitationally attracted by a central H2\rm H_2 clump would experience a first infall during which its density increases by 106\rm 10^6 in 1Myr\rm \sim 1 Myr. In this poster I begin to explore the phenomenology of mixed clumps made with H2\rm H_2 and WIMPs. Molecular clouds built with clumps are efficient machines to transform smooth distributions of WIMPs into concentrated networks. If WIMPs are neutralinos gravitationally attracted in clumps of such molecular clouds, they may either enrich the baryon sector over cosmological ages, or remain mixed with cold H2\rm H_2 clouds until the clumps evaporate either by collision or by stellar UV heating. A phenomenological model based on an hypothetic dark baryonic component (DBC) that was invoked in the past to explain one of the main drawbacks of CDM profiles, their overly dense cores, is briefly revisited in this context. The DBC is replaced by a mix of H2\rm H_2 and WIMPs, with a small fraction of HI produced by internal H2\rm H_2 collisions, in slightly dispersive clumpy clouds that may migrate from the halo towards inner parts of a galaxy and disk.Comment: 6 pages, 1 figure, submitted to Conference: XII International Symposium on Nuclei in the Cosmos August 5-12, 2012 Cairns, Australi

    Beyond binaries : rereading Yang Lian\u27s Norlang and Banpo

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    Chinese Religious Syncretism in Macau

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    In this paper I address the phenomenon of syncretism with respect to Chinese religions. An analysis of the syncretism that takes place between the three major Chinese religious traditions is first done in its personal and social dimensions. The social structure of Chinese religion is then used as a framework to understand how Buddhism and Daoism were made compatible with Confucianism. All this will serve as a background for the case study of Macau, where Chinese religious syncretism is very much alive. Three popular religious festivals are celebrated annually and simultaneously on the eighth day of the fourth lunar month, namely, zuilongjie (醉龍節) Feast of the Drunken Dragon, tangongdan (譚公誕) Tam Kung Festival and fodanjie (佛誕節) Feast of the Buddha

    Cronin effect and high-p_T suppression from the Color Glass Condensate

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    I give a pedagogical survey of the nuclear collective effects associated with gluon saturation and their impact on particle production in high-energy proton (or deuteron)-nucleus collisions at RHIC. At central rapidity, the theory predicts a Cronin peak due to independent multiple scattering off the valence quarks in the nucleus. At forward rapidities, the peak flattens out and disappears very fast, because of the correlations induced through quantum evolution in the nuclear gluon distribution at small x. Also, the ratio R_{pA} between the particle yield in proton-nucleus and proton-proton collisions is rapidly suppressed when increasing the rapidity, because of saturation effects which slow down the evolution of the nucleus compared to that of the proton. This behaviour could be responsible for a similar trend observed in the deuteron-nucleus collisions at RHIC.Comment: 22 pages, 10 eps figures, Invited talk at the International Workshop IX Hadron Physics and VII Relativistic Aspects of Nuclear Physics (HADRON-RANP 2004), Angra dos Reis, Brasil, March 28--April 03, 200

    Gluon Saturation at small x

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    At very high energies, the relevant component of the hadron wavefunction can be described as a Color Glass Condensate, i.e., a state of high density gluonic matter whose distribution is random, but frozen over the relevant time scales. The weight function for this distribution obeys a renormalization group equation in the form of a functional Fokker-Planck equation. Its solution leads to an effective theory which predicts gluon saturation at sufficiently high energy, or small Bjorken's xx.Comment: 8 pages, talk given at XXXI International Symposium on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. URL http://ismd31.ccnu.edu.cn

    Wisdom in Aristotle and Aquinas: From Metaphysics to Mysticism

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    This essay contains an attempt to trace the evolution of the concept of wisdom as found in the thought of Aristotle and Aquinas in terms of how the philosophical concept of wisdom as an intellectual virtue is understood and used to express the theological concept of wisdom as a gift of the Holy Spirit. The main aim is to understand how Aquinas derived the concept of wisdom from Aristotle's metaphysics and developed it in his mysticism. This research is based on a close study of Book Six of Aristotle's Nichomachean Ethics, the corresponding sections of Aquinas' Sententia libri Ethicorum and question forty-five of the second part of the second part of Aquinas' Summa Theologiae. The insights gained from the study are then used to decipher the theoretical meaning of Augustine's famous saying: "love and do what thou wilt" and to expound on the practical value of wisdom for religious leaders

    The non-linear evolution of jet quenching

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    We construct a generalization of the JIMWLK Hamiltonian, going beyond the eikonal approximation, which governs the high-energy evolution of the scattering between a dilute projectile and a dense target with an arbitrary longitudinal extent (a nucleus, or a slice of quark-gluon plasma). Different physical regimes refer to the ratio L/τL/\tau between the longitudinal size LL of the target and the lifetime τ\tau of the gluon fluctuations. When L/τ1L/\tau \ll 1, meaning that the target can be effectively treated as a shockwave, we recover the JIMWLK Hamiltonian, as expected. When L/τ1L/\tau \gg 1, meaning that the fluctuations live inside the target, the new Hamiltonian governs phenomena like the transverse momentum broadening and the radiative energy loss, which accompany the propagation of an energetic parton through a dense QCD medium. Using this Hamiltonian, we derive a non-linear equation for the dipole amplitude (a generalization of the BK equation), which describes the high-energy evolution of jet quenching. As compared to the original BK-JIMWLK evolution, the new evolution is remarkably different: the plasma saturation momentum evolves much faster with increasing energy (or decreasing Bjorken's xx) than the corresponding scale for a shockwave (nucleus). This widely opens the transverse phase-space for the evolution and implies the existence of large radiative corrections, enhanced by the double logarithm ln2(LT)\ln^2(LT), with TT the temperature of the medium. This confirms and explains from a physical perspective a recent result by Liou, Mueller, and Wu (arXiv:1304.7677). The dominant corrections are smooth enough to be absorbed into a renormalization of the jet quenching parameter q^\hat q. This renormalization is controlled by a linear equation supplemented with a saturation boundary, which emerges via controlled approximations from the generalized BK equation alluded to above.Comment: 54 pages plus 4 appendices, 6 figure
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