On the amplitudes for the CP-conserving K±(KS)→π±(π0)ℓ+ℓ−K^\pm(K_S)\to\pi^\pm(\pi^0)\ell^+\ell^- rare decay modes

The amplitudes for the rare decay modes $K^\pm\to\pi^\pm\ell^+\ell^-$ and $K_S\to\pi^0\ell^+\ell^-$ are studied with the aim of obtaining predictions for them, such as to enable the possibility to search for violations of lepton-flavour universality in the kaon sector. The issue is first addressed from the perspective of the low-energy expansion, and a two-loop representation of the corresponding form factors is constructed, leaving as unknown quantities their values and slopes at vanishing momentum transfer. In a second step a phenomenological determination of the latter is proposed. It consists of the contribution of the resonant two-pion state in the $P$ wave, and of the leading short-distance contribution determined by the operator-product expansion. The interpolation between the two energy regimes is described by an infinite tower of zero-width resonances matching the QCD short-distance behaviour. Finally, perspectives for future improvements in the theoretical understanding of these amplitudes are discussed.Comment: 49 pages, 11 figures, matches the published versio

Assuming Regge trajectories in holographic QCD: from OPE to Chiral Perturbation Theory

The soft wall model in holographic QCD has Regge trajectories but wrong operator product expansion (OPE) for the two-point vectorial QCD Green function. We modify the dilaton potential to comply OPE. We study also the axial two-point function using the same modified dilaton field and an additional scalar field to address chiral symmetry breaking. OPE is recovered adding a boundary term and low energy chiral parameters, $F_\pi$ and $L_{10}$, are well described analytically by the model in terms of Regge spacing and QCD condensates. The model nicely supports and extends previous theoretical analyses advocating Digamma function to study QCD two-point functions in different momentum regions.Comment: Major changes to improve the presentation of the paper but main results unchanged. Added appendix on Regge progressio

Standard Model and New Physics contributions to KLK_L and KSK_S into four leptons

We study the $K_L$ and $K_S$ decays into four leptons ($e\bar{e}e\bar{e}, \, \mu\bar{\mu}\mu\bar{\mu},\, e\bar{e}\mu\bar{\mu}$) where we use a form factor motivated by vector meson dominance, and show the dependence of the branching ratios and spectra from the slopes. A precise determination of short distance contribution to $K_L\to \mu\mu$ is affected by our ignorance on the sign of the amplitude $\mathcal{A}(K_L\to \gamma\gamma)$ but we show a possibility to measure the sign of this amplitude by studying $K_L$ and $K_S$ decays in four leptons. We also investigate the effect of New Physics contributions for these decays.Comment: Improvements of the text and references adde

Spin-1 resonance contributions to the weak Chiral Lagrangian: the vector field formulation

We use the Vector formulation to evaluate vector and axial-vector exchange contributions to the O(p^4) weak Chiral Lagrangian. We recover in this framework the bulk of the contributions found previously by Ecker et al. in the antisymmetric formulation of vectors and axial-vectors, but new interesting features arise: i) most of our results are independent of Factorization and ii) novel contributions to non-leptonic kaon decays, proper of this formulation and phenomenologically interesting, are found. The phenomenological implications for K -> pi pi (pi) and radiative (anomalous and non-anomalous) non-leptonic kaon decays are thus investigated and found particularly relevant.Comment: 34 pages, plain LaTeX file, uses rotating.sty also include

Rare Kaon Decays Revisited

We present an updated discussion of K\ra\pi \bar{l} l decays in a combined framework of chiral perturbation theory and Large--$N_c$ QCD, which assumes the dominance of a minimal narrow resonance structure in the invariant mass dependence of the $\bar{l} l$ pair. The proposed picture reproduces very well, both the experimental K^+\ra\pi^+ e^+ e^- decay rate and the invariant $e^+ e^-$ mass spectrum. The predicted Br(K_S\ra\pi^0 e^+ e^-) is, within errors, consistent with the recently reported result from the NA48 collaboration. Predictions for the K\ra\pi \mu^{+}\mu^{-} modes are also obtained. We find that the resulting interference between the {\it direct} and {\it indirect} CP--violation amplitudes in K_L\ra\pi^0 e^+ e^- is constructive

Evans Syndrome Presented with Marginal Zone Lymphoma and Duodenal Neuroendocrine Tumor in an Elderly Woman

Summary Evans syndrome (ES) is an autoimmune disorder characterized by simultaneous or sequential development of autoimmune hemolytic anemia, immune thrombocytopenia, and/or neutropenia. ES can be classified as a primary (idiopathic) or secondary (associated with an underlying disease) syndrome. We report a case of ES in an elderly patient in the presence of multiple trigger factors such as recent influenza vaccine, marginal zone lymphoma, and neuroendocrine tumor G1. Whether this association is casual or causal remains a matter of speculation. It is however necessary to have a thorough work-up in a newly diagnosed ES and a more accurate search of miscellaneous factors especially in elderly patients

Role of permanent atrial fibrillation (AF) on long-term mortality in community-dwelling elderly people with and without chronic heart failure (CHF)

Permanent AF is characterized by an increased mortality in elderly subjects with CHF. Moreover, AF increased the risk of mortality also in elderly subjects without CHF. Thus, we examined long-term mortality in community-dwelling elderly people with and without CHF. A total of 1332 subjects aged 65 and older were selected from the electoral rolls of Campania, a region of southern Italy. The relationship between AF and mortality during a 12-year follow-up in 125 subjects with CHF and in 1.143 subjects without CHF were studied. Elderly subjects showed a higher mortality in those with respect to those without AF (72.1% vs. 51.8%; p < 0.01). Similarly, elderly subjects without CHF showed a higher mortality in those with respect to those without AF (61.8% vs. 49.8%; p < 0.05). In contrast, elderly subjects with CHF showed a similar mortality in those with respect to those without AF (74.7% vs. 82.4%; p = 0.234). Multivariate analysis shows that AF was predictive of mortality in all elderly subjects (Hazard Risk = HR = 1.39, 95% confidence interval (CI) = 1.25-2.82; p < 0.001). When the analysis was conducted considering the presence and the absence of CHF, AF was strongly predictive of mortality in elderly subjects without CHF (HR = 1.95, 95% CI = 1.25-4.51; p < 0.001) but not in those with CHF (HR = 1.12, 95% CI = 0.97-3.69; p = 0.321). We concluded that AF is able to predict long-term mortality in elderly subjects. Moreover, AF is strongly predictive of long-term mortality in the absence but not in the presence of CHF. (C) 2011 Elsevier Ireland Ltd. All rights reserved