1,152 research outputs found

    Renormalization of dimension-six operators relevant for the Higgs decays hγγ,γZh\rightarrow \gamma\gamma,\gamma Z

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    The discovery of the Higgs boson has opened a new window to test the SM through the measurements of its couplings. Of particular interest is the measured Higgs coupling to photons which arises in the SM at the one-loop level, and can then be significantly affected by new physics. We calculate the one-loop renormalization of the dimension-six operators relevant for hγγ,γZh\rightarrow \gamma\gamma, \gamma Z, which can be potentially important since it could, in principle, give log-enhanced contributions from operator mixing. We find however that there is no mixing from any current-current operator that could lead to this log-enhanced effect. We show how the right choice of operator basis can make this calculation simple. We then conclude that hγγ,γZh\rightarrow \gamma\gamma, \gamma Z can only be affected by RG mixing from operators whose Wilson coefficients are expected to be of one-loop size, among them fermion dipole-moment operators which we have also included.Comment: 21 pages. Improved version with h -> gamma Z results added and structure of anomalous-dimension matrix determined further. Conclusions unchange

    Numerical evolution of matter in dynamical axisymmetric black hole spacetimes. I. Methods and tests

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    We have developed a numerical code to study the evolution of self-gravitating matter in dynamic black hole axisymmetric spacetimes in general relativity. The matter fields are evolved with a high-resolution shock-capturing scheme that uses the characteristic information of the general relativistic hydrodynamic equations to build up a linearized Riemann solver. The spacetime is evolved with an axisymmetric ADM code designed to evolve a wormhole in full general relativity. We discuss the numerical and algorithmic issues related to the effective coupling of the hydrodynamical and spacetime pieces of the code, as well as the numerical methods and gauge conditions we use to evolve such spacetimes. The code has been put through a series of tests that verify that it functions correctly. Particularly, we develop and describe a new set of testbed calculations and techniques designed to handle dynamically sliced, self-gravitating matter flows on black holes, and subject the code to these tests. We make some studies of the spherical and axisymmetric accretion onto a dynamic black hole, the fully dynamical evolution of imploding shells of dust with a black hole, the evolution of matter in rotating spacetimes, the gravitational radiation induced by the presence of the matter fields and the behavior of apparent horizons through the evolution.Comment: 42 pages, 20 figures, submitted to Phys Rev

    Axion interpretation of the PVLAS data?

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    The PVLAS collaboration has recently reported the observation of a rotation of the polarization plane of light propagating through a transverse static magnetic field. Such an effect can arise from the production of a light, m_A ~ meV, pseudoscalar coupled to two photons with coupling strength g_{A\gamma} ~ 5x10^{-6} GeV^{-1}. Here, we review these experimental findings, discuss how astrophysical and helioscope bounds on this coupling can be evaded, and emphasize some experimental proposals to test the scenario.Comment: 4 pages, 1 figure, jpconf.cls, talk presented at the ninth International Conference on Topics in Astroparticle and Underground Physics, TAUP 2005, Zaragoza, Spain, September 10-14, 200

    New bounds on millicharged particles from cosmology

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    Particles with millicharge q and sub-eV mass can be produced in photon-photon collisions, distorting the energy spectrum of the Cosmic Microwave Background. We derive the conservative bound q < 10^-7 e (as well as model-dependent bounds two orders of magnitude stronger), incompatible with proposed interpretations of the PVLAS anomaly based on millicharged production or on millicharged-mediated axion-like couplings.Comment: 7 pages, 2 figures. Final versio

    HEMATURIA POR ROTURA DE ANEURISMA ILÍACO-URETERAL.

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    Arch Esp Urol. 2006 Apr;59(3):287-9. [Hematuria after ureteral-iliac aneurysm rupture] [Article in Spanish] Palacios A, Massó P, Osorio L, Oliveira A, Soares J, Marcelo F. Servicio de Urología, Hospital General de Santo Antonio, Porto, Portugal. [email protected] Abstract OBJECTIVE: Ureteral-iliac artery fistula is a rare condition. We perform a bibliographic review and report a case of ureter-iliac artery fistula reviewing its major differential diagnosis. METHODS: This case-study describes a patient with massive hematuria that presented a ureter-iliac artery fistula secondary to spontaneous rupture of an internal iliac artery aneurysm. RESULTS: 86 -year-old male patient with history of previous surgery for aneurysm and ureteral catheterization. CONCLUSIONS: This difficult diagnosis should be thought of in a patient with massive macroscopic hematuria and previous vascular surgery. The treatment is always surgery. PMID: 16724715 [PubMed - indexed for MEDLIN

    Self Interacting Dark Matter in the Solar System

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    Weakly coupled, almost massless, spin 0 particles have been predicted by many extensions of the standard model of particle physics. Recently, the PVLAS group observed a rotation of polarization of electromagnetic waves in vacuum in the presence of transverse magnetic field. This phenomenon is best explained by the existence of a weakly coupled light pseudoscalar particle. However, the coupling required by this experiment is much larger than the conventional astrophysical limits. Here we consider a hypothetical self-interacting pseudoscalar particle which couples weakly with visible matter. Assuming that these pseudoscalars pervade the galaxy, we show that the solar limits on the pseudoscalar-photon coupling can be evaded.Comment: 17 pages, 2 figure
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