424 research outputs found

    The Neutron Electric Dipole Moment in the Instanton Vacuum: Quenched Versus Unquenched Simulations

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    We investigate the role played by the fermionic determinant in the evaluation of the CP-violating neutron electric dipole moment (EDM) adopting the Instanton Liquid Model. Significant differences between quenched and unquenched calculations are found. In the case of unquenched simulations the neutron EDM decreases linearly with the quark mass and is expected to vanish in the chiral limit. On the contrary, within the quenched approximation, the neutron EDM increases as the quark mass decreases and is expected to diverge as (1/m)**Nf in the chiral limit. We argue that such a qualitatively different behavior is a parameter-free, semi-classical prediction and occurs because the neutron EDM is sensitive to the topological structure of the vacuum. The present analysis suggests that quenched and unquenched lattice QCD simulations of the neutron EDM as well as of other observables governed by topology might show up important differences in the quark mass dependence, for mq < Lambda(QCD).Comment: 8 pages, 3 figures, 2 table

    Responsive Urban Models by Processing Sets of Heterogeneous Data

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    This paper presents some steps in experimentation aimed at describing urban spaces made following the series of earthquakes that affected a vast area of central Italy starting on 24 August 2016. More specifically, these spaces pertain to historical centres of limited size and case studies that can be called "problematic" (due to complex morphological and settlement conditions, because they are difficult to access, or because they have been affected by calamitous events, etc.). The main objectives were to verify the use of sets of heterogeneous data that are already largely available to define a workflow and develop procedures that would allow some of the steps to be automated as much as possible. The most general goal was to use the experimentation to define a methodology to approach the problem aimed at developing descriptive responsive models of the urban space, that is, morphological and computer-based models capable of being modified in relation to the constantly updated flow of input data

    Health and Economic Impact of Surgical Site Infections Diagnosed after Hospital Discharge

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    Although surgical site infections (SSIs) are known to cause substantial illness and costs during the index hospitalization, little information exists about the impact of infections diagnosed after discharge, which constitute the majority of SSIs. In this study, using patient questionnaire and administrative databases, we assessed the clinical outcomes and resource utilization in the 8-week postoperative period associated with SSIs recognized after discharge. SSI recognized after discharge was confirmed in 89 (1.9%) of 4,571 procedures from May 1997 to October 1998. Patients with SSI, but not controls, had a significant decline in SF-12 (Medical Outcomes Study 12-Item Short-Form Health Survey) mental health component scores after surgery (p=0.004). Patients required significantly more outpatient visits, emergency room visits, radiology services, readmissions, and home health aide services than did controls. Average total costs during the 8 weeks after discharge were US5,155forpatientswithSSIand5,155 for patients with SSI and 1,773 for controls (p<0.001)

    Next-to-leading order strong interaction corrections to the Delta F=2 effective Hamiltonian in the MSSM

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    We compute the next-to-leading order strong interaction corrections to gluino-mediated Delta F=2 box diagrams in the Minimal Supersymmetric Standard Model. These corrections are given by two loop diagrams which we have calculated in three different regularization schemes in the mass insertion approximation. We obtain the next-to-leading order Wilson coefficients of the Delta F=2 effective Hamiltonian relevant for neutral meson mixings. We find that the matching scale uncertainty is largely reduced at the next-to-leading order, typically from about 10-15% to few percent.Comment: 26 pages, 8 figure

    The neutron electric dipole form factor in the perturbative chiral quark model

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    We calculate the electric dipole form factor of the neutron in a perturbative chiral quark model, parameterizing CP-violation of generic origin by means of effective electric dipole moments of the constituent quarks and their CP-violating couplings to the chiral fields. We discuss the relation of these effective parameters to more fundamental ones such as the intrinsic electric and chromoelectric dipole moments of quarks and the Weinberg parameter. From the existing experimental upper limits on the neutron EDM we derive constraints on these CP-violating parameters.Comment: 20 pages, 3 figure

    The inhibition of the highly expressed miR-221 and miR-222 impairs the growth of prostate carcinoma xenografts in mice

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    MiR-221 and miR-222 are two highly homologous microRNAs whose upregulation has been recently described in several types of human tumors, for some of which their oncogenic role was explained by the discovery of their target p27, a key cell cycle regulator. We previously showed this regulatory relationship in prostate carcinoma cell lines in vitro, underlying the role of miR-221/222 as inducers of proliferation and tumorigenicity

    On the Standard Model prediction for BR(B{s,d} to mu+ mu-)

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    The decay Bs to mu+ mu- is one of the milestones of the flavor program at the LHC. We reappraise its Standard Model prediction. First, by analyzing the theoretical rate in the light of its main parametric dependence, we highlight the importance of a complete evaluation of higher-order electroweak corrections, at present known only in the large-mt limit, and leaving sizable dependence on the definition of electroweak parameters. Using insights from a complete calculation of such corrections for K to pi bar{nu} nu decays, we find a scheme in which NLO electroweak corrections are likely to be negligible. Second, we address the issue of the correspondence between the initial and the final state detected by the experiments, and those used in the theoretical prediction. Particular attention is devoted to the effect of the soft radiation, that has not been discussed for this mode in the previous literature, and that can lead to O(10%) corrections to the decay rate. The "non-radiative" branching ratio (that is equivalent to the branching ratio fully inclusive of bremsstrahlung radiation) is estimated to be (3.23 +/- 0.27) x 10^{-9} for the flavor eigenstate, with the main uncertainty resulting from the value of f_{Bs}, followed by the uncertainty due to higher order electroweak corrections. Applying the same strategy to Bd to mu+ mu-, we find for its non-radiative branching ratio (1.07 +/- 0.10) x 10^{-10}.Comment: 15 pages. v3: very minor changes to match the journal version (EPJC

    Viability of MSSM scenarios at very large tan(beta)

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    We investigate the MSSM with very large tan(beta) > 50, where the fermion masses are strongly affected by loop-induced couplings to the "wrong" Higgs, imposing perturbative Yukawa couplings and constraints from flavour physics. Performing a low-energy scan of the MSSM with flavour-blind soft terms, we find that the branching ratio of B->tau nu and the anomalous magnetic moment of the muon are the strongest constraints at very large tan(beta) and identify the viable regions in parameter space. Furthermore we determine the scale at which the perturbativity of the Yukawa sector breaks down, depending on the low-energy MSSM parameters. Next, we analyse the very large tan(beta) regime of General Gauge Mediation (GGM) with a low mediation scale. We investigate the requirements on the parameter space and discuss the implied flavour phenomenology. We point out that the possibility of a vanishing Bmu term at a mediation scale M = 100 TeV is challenged by the experimental data on B->tau nu and the anomalous magnetic moment of the muon.Comment: 29 pages, 7 figures. v2: discussion in sections 1 and 4 expanded, conclusions unchanged. Matches version published in JHE

    The Impact of Flavour Changing Neutral Gauge Bosons on B->X_s gamma

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    The branching ratio of the rare decay B->X_s gamma provides potentially strong constraints on models beyond the Standard Model. Considering a general scenario with new heavy neutral gauge bosons, present in particular in Z' and gauge flavour models, we point out two new contributions to the B->X_s gamma decay. The first one originates from one-loop diagrams mediated by gauge bosons and heavy exotic quarks with electric charge -1/3. The second contribution stems from the QCD mixing of neutral current-current operators generated by heavy neutral gauge bosons and the dipole operators responsible for the B->X_s gamma decay. The latter mixing is calculated here for the first time. We discuss general sum rules which have to be satisfied in any model of this type. We emphasise that the neutral gauge bosons in question could also significantly affect other fermion radiative decays as well as non-leptonic two-body B decays, epsilon'/epsilon, anomalous (g-2)_mu and electric dipole moments.Comment: 31 pages, 5 figures; version published on JHEP; added magic QCD numbers for flavour-violating Z gauge boson contribution to B -> X_s gamm
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