6,931 research outputs found

    An example of resonance saturation at one loop

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    We argue that the large-Nc expansion of QCD can be used to treat a Lagrangian of resonances in a perturbative way. As an illustration of this we compute the L_10 coupling of the Chiral Lagrangian by integrating out resonance fields at one loop. Given a Lagrangian and a renormalization scheme, this is how in principle one can answer in a concrete and unambiguous manner questions such as at what scale resonance saturation takes place.Comment: 9 pages, 5 figures. Enlarged discussion, results unchanged. To be published in Phys. Rev.

    A relativistic chiral quark model for pseudoscalar emission from heavy mesons

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    The amplitudes for one-pion mediated transitions between heavy meson excited states are obtained in the framework of the relativistic chiral quark model. The effective coupling constants to pions and the decay widths of excited heavy mesons with l<=2 for non-radially excited, and the l=0 radially excited mesons are presented for both charmed and beauty mesons. We also discuss the allowed decays of strange excited heavy mesons by emission of a K-meson.Comment: 20 pages, revte

    X-ray Spectral Analysis of the Steady States of GRS 1915+105

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    We report on the X-ray spectral behavior within the steady states of GRS 1915+105. Our work is based on the full data set on the source obtained using the Proportional Counter Array on the Rossi X-ray Timing Explorer and 15 GHz radio data obtained using the Ryle Telescope. The steady observations within the X-ray data set naturally separated into two regions in the color-color diagram and we refer to them as steady-soft and steady-hard. GRS 1915+105 displays significant curvature in the coronal component in both the soft and hard data within the {\it RXTE}/PCA bandpass. A majority of the steady-soft observations displays a roughly constant inner disk radius (R_in), while the steady-hard observations display an evolving disk truncation which is correlated to the mass accretion rate through the disk. The disk flux and coronal flux are strongly correlated in steady-hard observations and very weakly correlated in the steady-soft observations. Within the steady-hard observations we observe two particular circumstances when there are correlations between the coronal X-ray flux and the radio flux with log slopes \eta~0.68 +/- 0.35 and \eta ~ 1.12 +/- 0.13. They are consistent with the upper and lower tracks of Gallo et al. (2012), respectively. A comparison of model parameters to the state definitions show that almost all steady-soft observations match the criteria of either thermal or steep power law state, while a large portion of the steady-hard observations match the hard state criteria when the disk fraction constraint is neglected.Comment: 21 pages, 15 figures, 2 tables. Accepted for publication in Ap

    Electroweak Hadronic Contributions to the muon g-2

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    We reanalyze the two-loop electroweak hadronic contributions to the muon g-2 that may be enhanced by large logarithms. The present evaluation is improved over those already existing in the literature by the implementation of the current algebra Ward identities and the inclusion of the correct short-distance QCD behaviour of the relevant hadronic Green's function.Comment: 29 pages, 6 figures, LaTeX. Typos fixe

    Luxación simultánea de las articulaciones interfalángica y metacarpofalángica del pulgar

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    La luxación volar de la articulación metacarpofalángica del pulgar es una lesión muy rara; sólo 3 casos de luxación simultánea de las articulaciones metacarpofalángica e interfalángica del pulgar han sido publicados. Presentamos un caso de luxación combinada de las dos articulaciones del pulgar en el que se realizó un tratamiento ortopédico, con resultado satisfactorio.Thumb metacarpo-phalangeal joint palmar dislocation are a very rare injuries. Only 3 reports of intherphalangeal and metacarpo-phalangeal joints dislocations in the same thumb have been Publisher. The following is a case report of simultaneous dislocation of the MCP and IF joints in a thumb treated with a closed reduction

    Non-renormalization of the full <VVA> correlator at two-loop order

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    By explicit calculation of the two-loop QCD corrections we show that for singlet axial and vector currents the full off-shell correlation function in the limit of massless fermions is proportional to the one-loop result, when calculated in the MS-bar scheme. By the same finite renormalization which is needed to make the one-loop anomaly exact to all orders, we arrive at the conclusion that two-loop corrections are absent altogether, for the complete correlator not only its anomalous part. In accordance with the one-loop nature of the correlator, one possible amplitude, which seems to be missing by accident at the one-loop level, also does not show up at the two-loop level.Comment: 6 pages, 1 figur

    Investigational systemic drugs for moderate to severe plaque psoriasis: What’s new?

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    Introduction: The therapeutic armamentarium for the treatment of psoriasis, a chronic inflammatory skin disease, is now reasonably broad and structured, with several therapeutic agents that demonstrated a successful long-term control of this condition. However, there are still unfulfilled gaps resulting from the inherent limitations of existing therapies, which have paved the way for the identification of new therapeutic strategies or the improvement of the existing ones. Areas covered: The aim of this review is to thoroughly explore new therapeutic strategies and novel drugs that are currently in the pipeline for the treatment of psoriasis, focusing primarily on agents that are currently in phase I/II of clinical development. Some of which retrace already existing therapeutic approaches, such as the IL23/Th17 pathway inhibition, while others unveil new and yet unexplored ones. Expert opinion: Since the therapeutic landscape of psoriasis is wide, it is not yet clear whether novel agents will fill the remaining gaps in the context of a broader and more diversified set of oral and biologic therapies. Nevertheless, with the development of precision medicine approaches, the development of innovative targeted drugs will still have a therapeutic rationale in psoriasis
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