2,372 research outputs found

    S3 as a flavour symmetry for quarks and leptons after the Daya Bay result on \theta 13

    Full text link
    We present a model based on the flavour group S3 X Z3 X Z6 to explain the main features of fermion masses and mixing. In particular, in the neutrino sector the breaking of the S3 symmetry is responsible for a naturally small r=\Delta m^2_sol/\Delta m^2_atm and suitable next-to-leading order corrections bring \theta 13 at the level of ~ 0.13, fully compatible with the recent Daya Bay result. In the quark sector, the model accommodates the different mass hierarchies in the up and down quark sectors as well as the Cabibbo angle and Vcb (or Vub, depending on the charge assignment of the right-handed b-quark) in the correct range.Comment: 15 pages, 3 figure

    The Golden Ratio Prediction for the Solar Angle from a Natural Model with A5 Flavour Symmetry

    Full text link
    We formulate a consistent model predicting, in the leading order approximation, maximal atmospheric mixing angle, vanishing reactor angle and tan {\theta}_12 = 1/{\phi} where {\phi} is the Golden Ratio. The model is based on the flavour symmetry A5 \times Z5 \times Z3, spontaneously broken by a set of flavon fields. By minimizing the scalar potential of the theory up to the next-to-leading order in the symmetry breaking parameter, we demonstrate that this mixing pattern is naturally achieved in a finite portion of the parameter space, through the vacuum alignment of the flavon fields. The leading order approximation is stable against higher-order corrections. We also compare our construction to other models based on discrete symmetry groups.Comment: 28 pages, 2 figures. Minor changes, references added. Corrected typos in Appendix A. Version appeared on JHE

    Hadronic production of bottom-squark pairs with electroweak contributions

    Get PDF
    We present the complete computation of the tree-level and the next-to-leading order electroweak contributions to bottom-squark pair production at the LHC. The computation is performed within the minimal supersymmetric extension of the Standard Model. We discuss the numerical impact of these contributions in several supersymmetric scenarios.Comment: 33 pages, v2: preprint numbers correcte

    You turn me cold: evidence for temperature contagion

    Get PDF
    Introduction During social interactions, our own physiological responses influence those of others. Synchronization of physiological (and behavioural) responses can facilitate emotional understanding and group coherence through inter-subjectivity. Here we investigate if observing cues indicating a change in another's body temperature results in a corresponding temperature change in the observer. Methods Thirty-six healthy participants (age; 22.9±3.1 yrs) each observed, then rated, eight purpose-made videos (3 min duration) that depicted actors with either their right or left hand in visibly warm (warm videos) or cold water (cold videos). Four control videos with the actors' hand in front of the water were also shown. Temperature of participant observers' right and left hands was concurrently measured using a thermistor within a Wheatstone bridge with a theoretical temperature sensitivity of <0.0001°C. Temperature data were analysed in a repeated measures ANOVA (temperature × actor's hand × observer's hand). Results Participants rated the videos showing hands immersed in cold water as being significantly cooler than hands immersed in warm water, F(1,34) = 256.67, p0.1). There was however no evidence of left-right mirroring of these temperature effects p>0.1). Sensitivity to temperature contagion was also predicted by inter-individual differences in self-report empathy. Conclusions We illustrate physiological contagion of temperature in healthy individuals, suggesting that empathetic understanding for primary low-level physiological challenges (as well as more complex emotions) are grounded in somatic simulation

    A consumer segmentation proposal in the wine sector.

    Get PDF
    O mercado de vinhos apresenta perspectiva de crescimento no Brasil para os pr?ximos anos. Contudo, s?o poucas as pesquisas acad?micas publicadas no pa?s que abordam a segmenta??o dos consumidores deste setor. Neste contexto, este estudo teve como objetivo identificar diferentes segmentos de consumidores no mercado de vinhos com base no comportamento apresentado durante o processo de decis?o de compra. Como m?todo de pesquisa, realizou-se um levantamento de campo. A amostra do estudo foi composta por 370 habitantes das cidades de Mariana e Ouro Preto, ambas localizadas no Estado de Minas Gerais. Para an?lise dos dados, efetuou-se uma An?lise de Clusters, a partir da qual foram identificados dois segmentos de consumidores: os eventuais e os apaixonados por vinho. Os consumidores eventuais compram por impulso e tem o pre?o como principal crit?rio de escolha. J? os consumidores apaixonados por vinhos compram de forma planejada e frequente, considerando v?rios crit?rios em sua escolha, pois se tornou um h?bito o consumo desse produto. Para estudos futuros, sugere-se que a metodologia de pesquisa utilizada seja aplicada em amostras de outras regi?es do pa?s. Adicionalmente, sugere-se que sejam utilizadas tamb?m outras bases de segmenta??o para avan?ar na identifica??o dos diferentes grupos de consumidores de vinhos no Brasil.The wine market presents growth prospects in Brazil for the coming years. Despite this, there is few published academic research in the country that explores consumer segmentation in this sector. In this context, this study aimed to identify different consumer segments in the wine market based on the behavior presented during the purchase decision process. To reach this objective, a survey was conducted using a sample consisted of 370 inhabitants of the cities of Mariana and Ouro Preto, both located in Minas Gerais state, Brazil. To analyze the collected data, a Clusters Analysis was carried out, through which it was possible to identify two segments of consumers: the occasional one and the enthusiastic one. Occasional consumers buy on impulse and have the price as the main criterion of choice. On the other hand, enthusiastic consumers buy frequently and in a planned way, considering several criteria in their choice, because wine consumption has become a habit. For future studies, it is suggested that the used research methodology is applied to samples from other regions of the country. In addition, it is suggested that other segmentation bases are used to contribute to the identification of different groups of wine consumers in Brazil

    Ultraviolet Completion of Flavour Models

    Full text link
    Effective Flavour Models do not address questions related to the nature of the fundamental renormalisable theory at high energies. We study the ultraviolet completion of Flavour Models, which in general has the advantage of improving the predictivity of the effective models. In order to illustrate the important features we provide minimal completions for two known A4 models. We discuss the phenomenological implications of the explicit completions, such as lepton flavour violating contributions that arise through the exchange of messenger fields.Comment: 18 pages, 8 figure

    Decaying Dark Matter in the Supersymmetric Standard Model with Freeze-in and Seesaw mechanims

    Get PDF
    Inspired by the decaying dark matter (DM) which can explain cosmic ray anomalies naturally, we consider the supersymmetric Standard Model with three right-handed neutrinos (RHNs) and R-parity, and introduce a TeV-scale DM sector with two fields \phi_{1,2} and a Z3Z_3 discrete symmetry. The DM sector only interacts with the RHNs via a very heavy field exchange and then we can explain the cosmic ray anomalies. With the second right-handed neutrino N_2 dominant seesaw mechanism at the low scale around 10^4 GeV, we show that \phi_{1,2} can obtain the vacuum expectation values around the TeV scale, and then the lightest state from \phi_{1,2} is the decay DM with lifetime around \sim 10^{26}s. In particular, the DM very long lifetime is related to the tiny neutrino masses, and the dominant DM decay channels to \mu and \tau are related to the approximate \mu-\tau symmetry. Furthermore, the correct DM relic density can be obtained via the freeze-in mechanism, the small-scale problem for power spectrum can be solved due to the decays of the R-parity odd meta-stable states in the DM sector, and the baryon asymmetry can be generated via the soft leptogensis.Comment: 24 pages,3 figure

    Minimal flavour violation extensions of the seesaw

    Full text link
    We analyze the most natural formulations of the minimal lepton flavour violation hypothesis compatible with a type-I seesaw structure with three heavy singlet neutrinos N, and satisfying the requirement of being predictive, in the sense that all LFV effects can be expressed in terms of low energy observables. We find a new interesting realization based on the flavour group SU(3)e×SU(3)ℓ+NSU(3)_e\times SU(3)_{\ell+N} (being ee and ℓ\ell respectively the SU(2) singlet and doublet leptons). An intriguing feature of this realization is that, in the normal hierarchy scenario for neutrino masses, it allows for sizeable enhancements of μ→e\mu \to e transitions with respect to LFV processes involving the τ\tau lepton. We also discuss how the symmetries of the type-I seesaw allow for a strong suppression of the N mass scale with respect to the scale of lepton number breaking, without implying a similar suppression for possible mechanisms of N productionComment: 14 pages, 6 figure

    Large-Theta(13) Perturbation Theory of Neutrino Oscillation for Long-Baseline Experiments

    Full text link
    The Cervera et al. formula, the best known approximate formula of neutrino oscillation probability for long-baseline experiments, can be regarded as a second-order perturbative formula with small expansion parameter epsilon \equiv Delta m^2_{21} / Delta m^2_{31} \simeq 0.03 under the assumption s_{13} \simeq epsilon. If theta_{13} is large, as suggested by a candidate nu_{e} event at T2K as well as the recent global analyses, higher order corrections of s_{13} to the formula would be needed for better accuracy. We compute the corrections systematically by formulating a perturbative framework by taking theta_{13} as s_{13} \sim \sqrt{epsilon} \simeq 0.18, which guarantees its validity in a wide range of theta_{13} below the Chooz limit. We show on general ground that the correction terms must be of order epsilon^2. Yet, they nicely fill the mismatch between the approximate and the exact formulas at low energies and relatively long baselines. General theorems are derived which serve for better understanding of delta-dependence of the oscillation probability. Some interesting implications of the large theta_{13} hypothesis are discussed.Comment: Fig.2 added, 23 pages. Matches to the published versio
    • …
    corecore