107 research outputs found

    Present and Future K and B Meson Mixing Constraints on TeV Scale Left-Right Symmetry

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    We revisit the ΔF=2\Delta F=2 transitions in the KK and Bd,sB_{d,s} neutral meson systems in the context of the minimal Left-Right symmetric model. We take into account, in addition to up-to-date phenomenological data, the contributions related to the renormalization of the flavor-changing neutral Higgs tree-level amplitude. These contributions were neglected in recent discussions, albeit formally needed in order to obtain a gauge independent result. Their impact on the minimal LR model is crucial and twofold. First, the effects are relevant in BB meson oscillations, for both CP conserving and CP violating observables, so that for the first time these imply constraints on the LR scenario which compete with those of the KK sector (plagued by long-distance uncertainties). Second, they sizably contribute to the indirect kaon CP violation parameter ε\varepsilon. We discuss the bounds from BB and KK mesons in both cases of LR symmetry: generalized parity (P\mathcal P) and charge conjugation (C\mathcal C). In the case of P\mathcal P, the interplay between the CP-violation parameters ε\varepsilon and ε′\varepsilon' leads us to rule out the regime of very hierarchical bidoublet vacuum expectation values v2/v1<mb/mt≃0.02v_2/v_1<m_b/m_t\simeq 0.02. In general, by minimizing the scalar field contribution up to the limit of the perturbative regime and by definite values of the relevant CP phases in the charged right-handed currents, we find that a right-handed gauge boson WRW_R as light as 3 TeV is allowed at the 95% CL. This is well within the reach of direct detection at the next LHC run. If not discovered, within a decade the upgraded LHCb and Super B factories may reach an indirect sensitivity to a Left-Right scale of 8 TeV.Comment: Refs added + comment

    Resummation in QFT with Meijer G-functions

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    We employ a recent resummation method to deal with divergent series, based on the Meijer G-function, which gives access to the non-perturbative regime of any QFT from the first few known coefficients in the perturbative expansion. Using this technique, we consider in detail the ϕ4\phi^4 model where we estimate the non-perturbative β−\beta-function and prove that its asymptotic behavior correctly reproduces instantonic effects calculated using semiclassical methods. After reviewing the emergence of the renormalons in this theory, we also speculate on how one can resum them. Finally, we resum the non-perturbative β−\beta-function of abelian and non-abelian gauge-fermion theories and analyze the behavior of these theories as a function of the number of fermion flavors. While in the former no fixed points are found, in the latter, a richer phase diagram is uncovered and illustrated by the regions of confinement, large-distance conformality, and asymptotic safety.Comment: 22 pages, 10 figures, final version with minor changes, as accepted in NP

    AS-BUILT RELIABILITY IN ARCHITECTURAL HBIM MODELING

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    Abstract. The As-Built Model cannot be considered as a simple three-dimensional mould of the studied reality but as a process of analysis, synthesis and communication of architectural complexity including, in addition to geometric-dimensional aspects, also the historical, aesthetic and architectural features of the building. Consequently, the transparency and reliability issues of the digital visualization constitutes, as well as for the field of archaeology, a matter of primary importance in the modelling of cultural heritage. The increasing interest of scholars in the application of Building Information Modelling (BIM) to historical buildings has renewed the problems related to the reliability of the As-built, related not only to the relationship between the model and the measure, but also to the other information, for example the constructive technologies. Based on the survey and modelling of some case studies, the paper's aim is to define a reference standard for the reliability declaration of the As-Built HBIM models, which considers both the geometric and information aspects.</p

    Smart Architectural and Urban Heritage: An Applied Reflection

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    The aim of this paper is to present the use of 3D models and augmented reality (AR) to study and communicate architectural and urban values and, therefore, favor the development of dedicated forms of "smart heritage". The study rises from a reflection on the concept of "heritage", as defined in the international documents, intended as an evolving idea that puts together tangible and intangible aspects. Moreover, digital technologies favor "phygital" applications where the digital dimension support the traditional ones. In this way, AR allows the superimposition of multimedia information to heritage, respecting the historical matter of the artefacts, and supporting a "smart heritage" application. In particular, mobile AR, with real-time and ubiquitous visualizations, offers the opportunity to show past urban and architectural configurations to investigate and describe the transformations that have led to the current configuration, and consequently highlighting the present historical and architectural values of the buildings. Two case studies are presented: the square of St. Basilio Monastery, with its historical transformations, and the Basilica of Collemaggio, a pivotal building in the rites of "Perdonanza Celestiniana"

    A consistent quantum field theory from dimensional reduction

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    We incorporate the concept of dimensional reduction at high energies within the perturbative formulation of quantum field theory. In this new framework, space and momentum integrations are modified by a weighting function incorporating an effective mass energy associated with the dimensional reduction scale. We quantize the theory within canonical formalism. We then show that it can be made finite in perturbation theory, free of renormalon ambiguities, and with better analytic behavior for infinitesimal coupling constant compared to standard quantum field theory. The new approach reproduces the known results at low energies. One key feature of this class of models is that the coupling constant always reaches a fixed point in the ultraviolet region, making the models ultra-violet complete.Comment: to appear in J. Phys. A Math. Theo

    K to \pi\pi\ hadronic matrix elements of left-right current-current operators

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    Effective \Delta S=1 four fermion operators involving left- and right-handed currents are relevant in left-right gauge extensions of the standard model and scalar extension of the Yukawa sector. They induce K to \pi\pi\ decays which are strictly constrained by experimental data, typically resulting in strong bounds on the new physics scales or parameters. We evaluate the K to \pi\pi\ hadronic matrix elements of such operators within the phenomenological framework of the Chiral Quark Model. The results are consistent with the estimates used in a previous work on TeV scale left-right symmetry, thus confirming the conclusions obtained there.Comment: Minor text changes. To appear on Phys. Rev.
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