634 research outputs found

    Forecasting Inflation using Economic Indicators: the Case of France

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    In order to provide short run forecasts of headline and core HICP inflation for France, we assess the forecasting performance of a large set of economic indicators, individually and jointly, as well as using dynamic factor models. We run out-of-sample forecasts implementing the Stock and Watson (1999) methodology. It turns out that, according to usual statistical criteria, the combination of several indicators -in particular those derived from surveys- provides better results than dynamic factor models, even after pre-selection of the variables included in the panel. However, factors included in VAR models exhibit more stable forecasting performance over time. Results for HICP excluding unprocessed food and energy are very encouraging. Moreover, we show that it is possible to use forecasts on this indicator to project overall inflation.Inflation ; Out-of-sample forecast ; Indicator models ; Dynamic factor models ; Phillips curve.

    A Tight Connection Between Direct and Indirect Detection of Dark Matter through Higgs Portal Couplings to a Hidden Sector

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    We present a hidden Abelian extension of the Standard Model including a complex scalar as a dark matter candidate and a light scalar acting as a long range force carrier between dark matter particles. The Sommerfeld enhanced annihilation cross-section of the dark matter explains the observed cosmic ray excesses. The light scalar field also gives rise to potentially large cross-sections of dark matter on nucleon, therefore providing an interesting way to probe this model simultaneously at direct and indirect dark matter search experiments. We constrain the parameter-space of the model by taking into account CDMS-II exclusion limit as well as PAMELA and FermiLAT data.Comment: 15 pages, 7 figures. Added discussions on tuning and inverse Compton scattering constraints. References added and updated. Matches the published versio

    HIV-1 DIS stem loop forms an obligatory bent kissing intermediate in the dimerization pathway.

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    The HIV-1 dimerization initiation sequence (DIS) is a conserved palindrome in the apical loop of a conserved hairpin motif in the 5′-untranslated region of its RNA genome. DIS hairpin plays an important role in genome dimerization by forming a ‘kissing complex’ between two complementary hairpins. Understanding the kinetics of this interaction is key to exploiting DIS as a possible human immunodeficiency virus (HIV) drug target. Here, we present a single-molecule Förster resonance energy transfer (smFRET) study of the dimerization reaction kinetics. Our data show the real-time formation and dissociation dynamics of individual kissing complexes, as well as the formation of the mature extended duplex complex that is ultimately required for virion packaging. Interestingly, the single-molecule trajectories reveal the presence of a previously unobserved bent intermediate required for extended duplex formation. The universally conserved A272 is essential for the formation of this intermediate, which is stabilized by Mg(2+), but not by K(+) cations. We propose a 3D model of a possible bent intermediate and a minimal dimerization pathway consisting of three steps with two obligatory intermediates (kissing complex and bent intermediate) and driven by Mg(2+) ions

    Flavour Matters in Leptogenesis

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    We give analytic approximations to the baryon asymmetry produced by thermal leptogenesis with hierarchical right-handed neutrinos. Our calculation includes flavour-dependent washout processes and CP violation in scattering, and neglects gauge interactions and finite temperature corrections. Our approximate formulae depend upon the three CP asymmetries in the individual lepton flavours as well as on three flavour-dependent efficiency factors. We show that the commonly used expressions for the lepton asymmetry, which depend on the total CP asymmetry and one single efficiency factor, may fail to reproduce the correct lepton asymmetry in a number of cases. We illustrate the importance of using the flavour-dependent formulae in the context of a two right-handed neutrino model.Comment: Additional typos corrected (in particular, the plots and captions now agree

    Study of flavour dependencies in leptogenesis

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    We study the impact of flavours on the efficiency factors and give analytical and numerical results of the baryon asymmetry taking into account the different charged lepton Yukawa contributions and the complete (diagonal and off-diagonal) LL to B−LB-L conversion AA matrix. With this treatment we update the lower bound on the lightest right-handed neutrino mass.Comment: 13 pages, 11 figures. typos corrected, some formulae modified. 2 figures and discussion adde

    Leptogenesis beyond the limit of hierarchical heavy neutrino masses

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    We calculate the baryon asymmetry of the Universe in thermal leptogenesis beyond the usual lightest right-handed (RH) neutrino dominated scenario (N_1DS) and in particular beyond the hierarchical limit (HL), M_1 << M_2 << M_3, for the RH neutrino mass spectrum. After providing some orientation among the large variety of models, we first revisit the central role of the N_1DS, with new insights on the dynamics of the asymmetry generation and then discuss the main routes departing from it, focusing on models beyond the HL. We study in detail two examples of `strong-strong' wash-out scenarios: one with `maximal phase' and the limit of very large M_3, studying the effects arising when delta_2=(M_2-M_1)/M_1 is small. We extend analytical methods already applied to the N_1DS showing, for example, that, in the degenerate limit (DL), the efficiency factors of the RH neutrinos become equal with the single decay parameter replaced by the sum. Both cases disprove the misconception that close RH neutrino masses necessarily lead to a final asymmetry enhancement and to a relaxation of the lower bounds on M_1 and on the initial temperature of the radiation-dominated expansion. We also explain why leptogenesis tends to favor normal hierarchy compared to inverted hierarchy for the left-handed neutrino masses.Comment: 30 pages, 8 figures; corrected typo in Eq. (67); shortened Introduction, Section 3 and Conclusions; one figure removed; added 2 references; to appear in JCA

    CP violation in scatterings, three body processes and the Boltzmann equations for leptogenesis

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    We obtain the Boltzmann equations for leptogenesis including decay and scattering processes with two and three body initial or final states. We present an explicit computation of the CP violating scattering asymmetries. We analyze their possible impact in leptogenesis, and we discuss the validity of their approximate expressions in terms of the decay asymmetry. In scenarios in which the initial heavy neutrino density vanishes, the inclusion of CP asymmetries in scatterings can enforce a cancellation between the lepton asymmetry generated at early times and the asymmetry produced at later times. We argue that a sizeable amount of washout is crucial for spoiling this cancellation, and we show that in the regimes in which the washouts are particularly weak, the inclusion of CP violation in scatterings yields a reduction in the final value of the lepton asymmetry. In the strong washout regimes the inclusion of CP violation in scatterings still leads to a significant enhancement of the lepton asymmetry at high temperatures; however, due to the independence from the early conditions that is characteristic of these regimes, the final value of the lepton asymmetry remains approximately unchanged.Comment: 24 pages, 6 figures. One appendix added. Some numerical results and corresponding figures (mainly fig. 3) corrected. Final version to be published in JHE

    Synthesis, Electrochemistry, and Excited-State Properties of Three Ru(II) Quaterpyridine Complexes

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    The complexes [Ru(qpy)LL′]2+ (qpy = 2,2′:6′,2″:6″,2‴-quaterpyridine), with 1: L = acetonitrile, L′= chloride; 2: L = L′= acetonitrile; and 3: L = L′= vinylpyridine, have been prepared from [Ru(qpy) (Cl)2]. Their absorption spectra in CH3CN exhibit broad metal-to-ligand charge transfer (MLCT) absorptions arising from overlapping 1A1 → 1MLCT transitions. Photoluminescence is not observed at room temperature, but all three are weakly emissive in 4:1 ethanol/methanol glasses at 77 K with broad, featureless emissions observed between 600 and 1000 nm consistent with MLCT phosphorescence. Cyclic voltammograms in CH3CN reveal the expected RuIII/II redox couples. In 0.1 M trifluoroacetic acid (TFA), 1 and 2 undergo aquation to give [RuII(qpy)(OH2)2]2+, as evidenced by the appearance of waves for the couples [RuIII(qpy)(OH2)2]3+/[RuII(qpy)(OH2)2]2+, [RuIV(qpy)(O)(OH2)]2+/[RuIII(qpy)(OH2)2]3+, and [RuVI(qpy)(O)2]2+/[RuIV(qpy)(O)(OH2)]2+ in cyclic voltammograms
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