1,138 research outputs found

    The effect of primordial temperature fluctuations on the QCD transition

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    We analyze a new mechanism for the cosmological QCD first-order phase transition: inhomogeneous nucleation. The primordial temperature fluctuations are larger than the tiny temperature interval, in which bubbles would form in the standard picture of homogeneous nucleation. Thus the bubbles nucleate at cold spots. We find the typical distance between bubble centers to be a few meters. This exceeds the estimates from homogeneous nucleation by two orders of magnitude. The resulting baryon inhomogeneities may affect primordial nucleosynthesis.Comment: 6 pages, 1 figure. To appear in the Proceedings of Strong and Electroweak Matter 2000 (SEWM2000), Marseilles, France, 14-17 June 200

    The QCD phase transition in the inhomogeneous Universe

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    We investigate a new mechanism for the cosmological QCD phase transition: inhomogeneous nucleation. The primordial temperature fluctuations, measured to be ÎŽT/T∌10−5\delta T/T \sim 10^{-5}, are larger than the tiny temperature interval, in which bubbles would form in the standard picture of homogeneous nucleation. Thus the bubbles nucleate at cold spots. We find the typical distance between bubble centers to be a few meters. This exceeds the estimates from homogeneous nucleation by two orders of magnitude. The resulting baryon inhomogeneities may affect primordial nucleosynthesis.Comment: Version to appear in Phys. Rev. Lett., 4 pages, 1 figure. Difference to heterogeneous nucleation emphasized, amplitude of temperature fluctuations analyzed in more detail, new length scale l_heat introduced, more complicated geometry of baryon number discussed shortly (relevant for low values of l_heat

    Cosmological Phase Transitions

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    Physical processes related to cosmological first-order phase transitions are discussed and reviewed in this introductory part of dissertation. I first describe cosmological phase transitions on a general level, concentrating on bubble nucleation, phase change, and related phenomena. I point out that especially the onset of a cosmological phase transition shows a universal behavior. Then I discuss the electroweak and quark-hadron phase transitions from a more phenomenological point of view, and present a partially quantitative description of the different events that is believed to have taken place during these two cosmological transitions.Comment: introductory part of Ph.D. dissertation, 53 LaTeX pages + 10 figures not included. (Figs are available via airmail, or as a 430 kB PostScript file via anonymous ftp at fltxc.helsinki.fi (128.214.3.11), directory /pub, file phdfigs.ps .) HU-TFT-IR-93-

    John T. Loughran--An Appreciation: The Man

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    Prothrombin complex concentrates or recombinant factor VIIa are more effective than fresh-frozen plasma at lowering INR in patients with liver disease

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    A critical appraisal and clinical application of Kwon JO, MacLaren R. Comparison of fresh-frozen plasma, four-factor prothrombin complex concentrates, and recombinant factor VIIa to facilitate procedures in critically ill patients with coagulopathy from liver disease: a retrospective cohort study. Pharmacotherapy. 2016;36(10):1047-1054. doi: 10.1002/phar.182

    B_s meson excited states from the lattice

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    This is a follow-up to our earlier work [Phys. Rev. D 65, 014512 (2002); Eur. Phys. J. C 28, 79 (2003); Phys. Rev. D 69, 094505 (2004)] for the energies and the charge (vector) and matter (scalar) distributions for S-wave states in a heavy-light meson, where the heavy quark is static and the light quark has a mass about that of the strange quark. We study the radial distributions of higher angular momentum states, namely P- and D-wave states. In nature the closest equivalent of this heavy-light system is the B_s meson. The calculation is carried out with dynamical fermions on a 16^3 times 32 lattice with a lattice spacing of about 0.10 fm generated with the non-perturbatively improved clover action. It is shown that several features of the energies and radial distributions are in qualitative agreement with what one expects from a simple one-body Dirac equation interpretation.Comment: 6 pages, poster presented at Lattice 2005 (Heavy quarks
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