5,012 research outputs found

    The Changing Role of Global Financial Brands in the Underwriting of Foreign Government Debt (1815-2010)

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    This paper covers the long-term evolution of the primary market for foreign government debt. We discuss the role of financial intermediaries as underwriters and distributors of securities, providers of information, and lending of last resort services since the early 19th century, and the evolution of this role. We underscore the role of the prestige of global financial brands in sustaining early foreign debt markets and its weakening in the modern era.Sovereign debt, primary bond market, reputation, underwriting, certification, information asymmetries, investment banking, credit rating agencies, IMF

    Application of the operator product expansion to the short distance behavior of nuclear potentials

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    We investigate the short distance behavior of nucleon-nucleon (NN) potentials defined through Bethe-Salpeter wave functions, by perturbatively calculating anomalous dimensions of 6-quark operators in QCD. Thanks to the asymptotic freedom of QCD, 1-loop computations give certain exact results for the potentials in the zero distance limit. In particular the functional form of the S-state central NN potential at short distance rr is predicted to be a little weaker than r−2r^{-2}. On the other hand, due to the intriguing character of the anomalous dimension spectrum, perturbative considerations alone can not determine whether this potential is repulsive or attractive at short distances. A crude estimation suggests that the force at short distance is repulsive, as found numerically in lattice QCD. A similar behavior is found for the tensor potential.Comment: 40 pages, no figure

    Associations of maternal angiogenic factors during pregnancy with childhood carotid intima-media thickness and blood pressure

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    BACKGROUND AND AIMS: Reduced maternal placental growth factor (PlGF) and higher soluble fms-like tyrosine kinase (sFlt-1) concentrations in pregnancy may have persistent effects on offspring vasculature. We hypothesized that suboptimal maternal angiogenic factors in pregnancy may adversely affect fetal vascular development, leading to an increased risk of adverse atheriosclerotic adaptations and higher blood pressure in offspring. METHODS: In a population-based prospective cohort among 4565 women and their offspring, we examined the associations of maternal serum PlGF and sFlt-1 concentrations in the first half of pregnancy with offspring vascular development. We measured childhood blood pressure and obtained childhood carotid intima media thickness and carotid distensibility through ultrasonography at 9 years. RESULTS: After adjustment for maternal sociodemographic and lifestyle characteristics, no associations were present of maternal first and second trimester angiogenic factors with childhood blood pressure, carotid intima media thickness (IMT) or distensibility in the total population. In preterm born children only, higher maternal second trimester PlGF concentrations, but not sFlt-1 concentrations, were associated with a lower childhood diastolic blood pressure (difference: -0.16 SDS (95% CI -0.30, –0.03) per SDS increase in maternal second trimester PlGF concentration). No associations among children born small-for-gestational age were present. CONCLUSIONS: In a low-risk population, maternal angiogenic factors in the first half of pregnancy are not associated with childhood blood pressure, carotid IMT or carotid distensibility after considering maternal socio-demographic and lifestyle factors. Only in children born preterm, lower maternal second trimester PlGF concentrations are associated with higher childhood diastolic blood pressure, but not with other vascular outcomes

    Supergravity Radiative Effects on Soft Terms and the Ό\mu Term

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    We compute quadratically divergent supergravity one-loop effects on soft supersymmetry-breaking parameters and the Ό\mu term in generic hidden sector supergravity models. These effects can significantly modify the matching condition for soft parameters at the Planck scale and also provide several new sources of the Ό\mu term which are naturally of order the weak scale. We also discuss some phenomenological implications of these effects, particularly the violation of the scalar mass universality which may lead to dangerous FCNC phenomena, and apply the results to superstring effective supergravity models.Comment: 12 pages, REVTEX. One reference is adde

    IFS impact in Mexico : 25 years of support to scientists

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    CP violation in 5D Split Fermions Scenario

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    We give a new configuration of split fermion positions in one extra dimension with two different Yukawa coupling strengths for up-type, huh_u, and down-type, hdh_d, quarks at huhd=36.0\frac{h_u}{h_d}=36.0. The new configurations can give enough CP violating (CPV) phase for accommodating all currently observed CPV processes. Therefore, a 5D standard model with split fermions is viable. In addition to the standard CKM phase, new CPV sources involving Kaluza-Klein(KK) gauge bosons coupling which arise from the fact that unitary rotation which transforms weak eigenstates into their mass eigenstates only holds for the zero modes which are the SM fields and not for the KK excitations. We have examined the physics of kaon, neutron, and B/DB/D mesons and found the most stringent bound on the size RR of the extra dimension comes from âˆŁÏ”K∣|\epsilon_K|. Moreover, it depends sensitively on the width, σ\sigma, of the Gaussian wavefunction in the extra dimension used to describe of the fermions. When σ/Râ‰Ș1\sigma/R \ll 1, the constraint will be lifted due to GIM suppression on the flavor changing neutral current(FCNC) and CPV couplings.Comment: 24 pages, 8 figure

    Semileptonic Hyperon Decays and CKM Unitarity

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    Using a technique that is not subject to first-order SU(3) symmetry breaking effects, we determine the VusV_{us} element of the CKM matrix from data on semileptonic hyperon decays. We obtain VusV_{us} =0.2250(27). This value is of similar precision to the one derived from Kl3K_{l3}, but higher and in better agreement with the unitarity requirement, ∣Vud∣2+∣Vus∣2+∣Vub∣2=1|V_{ud}|^2+|V_{us}|^2+|V_{ub}|^2=1.Comment: 3 pages, 1 tabl
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