2,750 research outputs found

    Flavour Physics and CP Violation in the Standard Model and Beyond

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    We present the invited lectures given at the Third IDPASC School which took place in Santiago de Compostela in January 2013. The students attending the school had very different backgrounds, some of them were doing their Ph.D. in experimental particle physics, others in theory. As a result, and in order to make the lectures useful for most of the students, we focused on basic topics of broad interest, avoiding the more technical aspects of Flavour Physics and CP Violation. We make a brief review of the Standard Model, paying special attention to the generation of fermion masses and mixing, as well as to CP violation. We describe some of the simplest extensions of the SM, emphasising novel flavour aspects which arise in their framework.Comment: Invited talk at the Third IDPASC School 2013, January 21st - February 2nd 2013, Santiago de Compostela, Galiza, Spain; 36 pages, 8 figures, 2 tables; version with few misprints correcte

    Bounds on gamma from CP violation measurements in B -> pi+ pi- and B -> psi K_S

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    We study the determination of gamma from CP-violating observables in B -> pi+ pi- and B -> psi K_S. This determination requires theoretical input to one combination of hadronic parameters. We show that a mild assumption about this quantity may allow bounds to be placed on gamma, but we stress the pernicious effects that an eightfold discrete ambiguity has on such an analysis. The bounds are discussed as a function of the direct (C) and interference (S) CP-violating observables obtained from time-dependent B -> pi+ pi- decays, and their behavior in the presence of new physics effects in B-Bbar mixing is studied. (V2: Misprints corrected. Slightly improved discussion.)Comment: 11 pages, RevTex 4, 5 eps figures include

    Seismic performance assessment of a timber log house

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    The current work presents a full scale shaking table test conducted on a twostoreyed timber log house, designed according to the state of the art on timber engineering. The test was performed within the framework of the SERIES Project “Multi-storey timber buildings” at LNEC, Lisbon, Portugal. Several tests and studies have been carried out by the University of Minho to characterize the behavior of the different components (logs, walls, slabs, connections, etc.) of log houses in the past few years for the European Technical Approval (ETA) of this construction system. The main results of the shaking table test are presented along with the preliminary analysis of the overall behavior of the log house. The analysis was carried out based on the shaking table tests and on a numerical model developed to estimate the main seismic parameters using the data obtained from the different individual studies on each component of the construction system performed within the framework of the ETA

    Seismic analysis of a 2-storey log house

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    The current paper deals with the analysis of the results yielded by a series of tests performed to evaluate the seismic behaviour of a model log construction. The study was based on an experimental investigation performed to improve the existing knowledge on log houses subject to seismic events. The main part of the experimental work is based on a full scale shaking table test, conducted on a two-storey log house designed by the Portuguese company Rusticasa¼ in compliance with design rules for timber buildings. The test was performed by the University of Minho within the framework of the SERIES Project ‘Multi-storey timber buildings’ and was coordinated by the University of Trento, at LNEC, Lisbon, Portugal. The geometry of the specimen, the design of the test, the setup and the instrumentation layout are first presented in this paper. The test procedure was conducted in stages with maximum accelerations (bi-directional) of 0.07g, 0.28g and 0.5g. The experimental results of each test have been analyzed and the resultant values of inter-storey drift, wall slippage and uplift measurements, shear deformations and hold-down forces measured are presented. Most importantly, the dynamic properties (fundamental period and mode shapes) of the system have been determined

    On fermion masses and mixing in a model with A4A_4 symmetry

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    In a recently proposed multi-Higgs extension of the standard model in which discrete symmetries, A4A_4 and Z3Z_3 are imposed we show that, after accommodating the fermion masses and the mixing matrices in the charged currents, the mixing matrices in the neutral currents induced by neutral scalars are numerically obtained. However, the flavor changing neutral currents are under control mainly by mixing and/or mass suppressions in the neutral scalar sector.Comment: Version accepted for publication in International Journal of Modern Physics A. In this version we added a discussion on the charged lepton and neutrino masses. The title has been changed. Other minor changes do not modify the conclusion

    Mass matrices and eigenstates for scalars / pseudoscalars; indirect CP violation, mass hierarchies and symmetry breaking

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    I study indirect CP violation for neutral kaons, and extend it to large values of the CP-violating parameter (taken to be real). I show how and at which condition there can exist a continuous set of basis in which the kinetic and mass terms in the Lagrangian can be diagonalized simultaneously. An ambiguity results for the mass spectrum, which then depends on the basis. In particular, for fixed (positive) (mass)^2 of the CP eigenstates K^0_1, K^0_2, and for certain ranges of values of the CP-violating parameter, a negative (mass)^2 can arise in the CP-violating basis. Under certain conditions, even a small perturbation, by lifting the ambiguity, can strongly alter the pattern of masses. These investigations extend in a natural way to indirect CP violation among a set of Higgs-like doublets. The C-odd commutator [K^0, K^0 bar], or its equivalent for Higgs multiplets, plays an important role. The condition for its vanishing and its consequences are among the main concerns of this work.Comment: LaTeX2e, 35 pages, 10 postscript figures + 1 log

    Fundamental CP-violating quantities in a SU(2)⊗ \otimes U(1) model with many Higgs doublets

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    We consider a SU(2)⊗ \otimes U(1) gauge theory with many scalar doublets, but without fermions. We devise a systematic method of constructing quantities which are invariant under changes of basis of the scalar fields, but acquire a minus sign under a general CP transformation. Those quantities provide a basis-independent way of checking for the existence of CP violation.Comment: (Latex file, 9 pages). CMU-preprin

    Sustainability and cultural heritage buildings

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    [Excerpt from Introduction] Conservation of cultural heritage buildings is a demand from society, which recognizes this heritage as a part of their identity, but it is also an economical issue. In Europe, tourism accounts for 10% of the GDP and 12% of the employment, if linked sectors are considered [x.1]. The EU is the world's number one tourist destination, with 40 % of arrivals in the world and with 7 European countries among the top ten [x.2]. According to the WTO estimates, international tourist arrivals in Europe will increase significantly. The built European heritage, namely monuments or historical centres, is a main attractor for tourism, with 45% of the UNESCO World Heritage sites within the EU. Therefore, the need for their conservation is unquestionable. [...

    Orthogonal Higgs bundles with singular spectral curves

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    We examine Higgs bundles for non-compact real forms of SO(4,C) and the isogenous complex group SL(2,C)XSL(2,C). This involves a study of non-regular fibers in the corresponding Hitchin fibrations and provides interesting examples of non-abelian spectral data.Comment: v3. Minor typos corrected and a dedication added. To appear in CAG in a special volume in honor of Karen Uhlenbeck's 75th birthda
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