107 research outputs found
Present and Future K and B Meson Mixing Constraints on TeV Scale Left-Right Symmetry
We revisit the transitions in the and 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 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 sector (plagued by
long-distance uncertainties). Second, they sizably contribute to the indirect
kaon CP violation parameter . We discuss the bounds from and
mesons in both cases of LR symmetry: generalized parity () and
charge conjugation (). In the case of , the interplay
between the CP-violation parameters and leads us
to rule out the regime of very hierarchical bidoublet vacuum expectation values
. 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 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
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 model where we estimate the
non-perturbative 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 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
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
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
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
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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