Flavour Physics and CP Violation in the Standard Model and Beyond

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

The D0 same-charge dimuon asymmetry and possibile new CP violation sources in the Bs−BˉsB_s-\bar{B}_s system

Recently, the D0 collaboration reported a large CP violation in the same-sign dimuon charge asymmetry which has the $3.2 \sigma$ deviation from the value estimated in the Standard Model. In this paper, several new physics models are considered: the MSSM, two Higgs doublet model, the recent dodeca model, and a new $Z'$ model. Generally, it is hard to achieve such a large CP violation consistently with other experimental constraints. We find that a scheme with extra non-anomalous U(1)$'$ gauge symmetry is barely consistent. In general, the extra $Z'$ gauge boson induces the flavor changing neutral current interactions at tree level, which is the basic reason allowing a large new physics CP violation. To preserve the U(1)$'$ symmetry at high energy, SU(2)$_L$ singlet exotic heavy quarks of mass above 1 TeV and the Standard Model gauge singlet scalars are introduced.Comment: 12 pages, 13 figure

Basis invariant conditions for supersymmetry in the two-Higgs-doublet model

The minimal supersymmetric standard model involves a rather restrictive Higgs potential with two Higgs fields. Recently, the full set of classes of symmetries allowed in the most general two Higgs doublet model was identified; these classes do not include the supersymmetric limit as a particular class. Thus, a physically meaningful definition of the supersymmetric limit must involve the interaction of the Higgs sector with other sectors of the theory. Here we show how one can construct basis invariant probes of supersymmetry involving both the Higgs sector and the gaugino-higgsino Higgs interactions.Comment: RevTex, 11 pages, v2-small section adde

Mean-field calculation of critical parameters and log-periodic characterization of an aperiodic-modulated model

We employ a mean-field approximation to study the Ising model with aperiodic modulation of its interactions in one spatial direction. Two different values for the exchange constant, $J_A$ and $J_B$, are present, according to the Fibonacci sequence. We calculated the pseudo-critical temperatures for finite systems and extrapolate them to the thermodynamic limit. We explicitly obtain the exponents $\beta$, $\delta$, and $\gamma$ and, from the usual scaling relations for anisotropic models at the upper critical dimension (assumed to be 4 for the model we treat), we calculate $\alpha$, $\nu$, $\nu_{//}$, $\eta$, and $\eta_{//}$. Within the framework of a renormalization-group approach, the Fibonacci sequence is a marginal one and we obtain exponents which depend on the ratio $r \equiv J_B/J_A$, as expected. But the scaling relation $\gamma = \beta (\delta -1)$ is obeyed for all values of $r$ we studied. We characterize some thermodynamic functions as log-periodic functions of their arguments, as expected for aperiodic-modulated models, and obtain precise values for the exponents from this characterization.Comment: 17 pages, including 9 figures, to appear in Phys. Rev.

Tree-level FCNC in the B system: from CP asymmetries to rare decays

Tree-level Flavor-Changing Neutral Currents (FCNC) are characteristic of models with extra vector-like quarks. These new couplings can strongly modify the B^0 CP asymmetries without conflicting with low--energy constraints. In the light of a low CP asymmetry in B --> J/\psi K_{S}, we discuss the implications of these contributions. We find that even these low values can be easily accommodated in these models. Furthermore, we show that the new data from B factories tend to favor an O(20) enhancement of the b --> d l \bar{l} transition over the SM expectation.Comment: 5 pages, 4 figures. Accepted version in PRD. Updated analysis with the new results from BaBar and BELLE. Figures enlarged, small typos corrected. Conclusions essentially unchange

Large Neutrino Mixing with Universal Strength of Yukawa Couplings

We analyse, within the framework of universal strength for Yukawa couplings (USY), various structures for the Dirac and Majorana neutrino mass matrices giving rise, through the see-saw mechanism, to a degenerate mass spectrum. A specific USY ansatz is presented for the charged lepton and neutrino effective mass matrix, leading to quasi-degenerate neutrinos and a leptonic mixing matrix which provides a large angle solution for both the atmospheric and solar neutrino problems.Comment: 7 pages, ReVTeX, small comments adde

Leptogenesis with exclusively low-energy CP Violation in the Context of Minimal Lepton Flavour Violation

We analyze lepton flavour violation (LFV) and the generation of the observed baryon-antibaryon asymmetry of the Universe (BAU) within a generalized minimal lepton flavour violation framework with three quasi-degenerate heavy Majorana neutrinos. The BAU which is obtained through radiative resonant leptogenesis can successfully be generated widely independent of the Majorana scale in this scenario and flavour effects are found to be relevant. Then we discuss the specific case in which CP violation is exclusively present at low-energies (a real R matrix) in the flavour sensitive temperature regime. Successful leptogenesis in this case leads to strong constraints on low-energy neutrino parameters.Comment: Contrubution to the proceedings of the EPS HEP 2007 conference, Manchester (UK). 3 pages, 3 figure

Estudo de betões eco-eficientes através da utilização de cinzas volantes de biomassa

A indústria do betão é, na actualidade, constantemente desafiada a minimizar o consumo de recursos naturais, matérias-primas e energia, assim como melhorar a performance ambiental dos materiais que produz. O cimento Portland é um dos materiais que contribui significativamente para a emissão de dióxido de carbono para atmosfera e, consequentemente, para o aquecimento global. Por outro lado, são utilizadas na sua produção grandes quantidades de matérias-primas e energia. Deste modo, é uma mais-valia a sua substituição nos materiais de construção, tais como o betão, por materiais que mantenham as mesmas propriedades mecânicas e de durabilidade, mas permitindo produzir um material mais sustentável. Um estudo experimental foi desenvolvido com o intuito de se avaliara influência de cinzas volantes de biomassa nas propriedades de betões com elevados teores de cinzas volantes. As cinzas volantes de biomassa foram usadas como reservatório de alcalinidade, para se tentar perceber se estas permitem minorar os problemas relacionados com este tipo de betões, nomeadamente o problema da carbonatação, e consequentemente da corrosão das infraestruturas metálicas. Foram estudadas propriedades frescas e endurecidas, tais como: espalhamento, resistências mecânicas e carbonatação. Os resultados mostram que a adição, ao conteúdo total do ligante, de apenas 0,5%m de cinzas volantes de biomassa, conduz a uma melhoria em termos de qualidade e durabilidade do betão, quando comparado comum betão com elevado teor de cinzas eum betão convencional (só com cimento como ligante). Deste modo, com a utilização de cinzas volantes de biomassa, é possível a produção de materiais de construção com baixo teor de cimento, com resistências mecânicas satisfatórias e duráveis, mas com uma melhoria significativa na performance ambiental destes materiais.Os autores querem agradecer à FCT (Fundação para a Ciência e Tecnologia – Portugal) e ao programa doutoral Eco-Construction and Rehabilitation por ajudarem no suporte financeiro através da bolsa com a referência PD/BD/52661/2014. Este trabalho foi também financiado pelo FEDER, através de fundos do programa “Competitivity Factors Operational Programme” - COMPETE e por fundos nacionais através do projecto POCI-01-0145-FEDER-007633 e pelo programa operacional regional CENTRO2020 no âmbito do projecto CENTRO-01-0145-FEDER-000006.info:eu-repo/semantics/publishedVersio