4,337 research outputs found

    Tolerance After Liver Transplantation: Where Are We?

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    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

    Area Quantization in Quasi-Extreme Black Holes

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    We consider quasi-extreme Kerr and quasi-extreme Schwarzschild-de Sitter black holes. From the known analytical expressions obtained for their quasi-normal modes frequencies, we suggest an area quantization prescription for those objects.Comment: Final version to appear in Mod. Phys. Lett.

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

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    Recently, the D0 collaboration reported a large CP violation in the same-sign dimuon charge asymmetry which has the 3.2σ3.2 \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′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′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_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

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    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

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    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, JAJ_A and JBJ_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 β\beta, δ\delta, and γ\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 α\alpha, ν\nu, ν//\nu_{//}, η\eta, and η//\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≡JB/JAr \equiv J_B/J_A, as expected. But the scaling relation γ=β(δ−1)\gamma = \beta (\delta -1) is obeyed for all values of rr 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.

    Numerical simulation study of the dynamical behavior of the Niedermayer algorithm

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    We calculate the dynamic critical exponent for the Niedermayer algorithm applied to the two-dimensional Ising and XY models, for various values of the free parameter E0E_0. For E0=−1E_0=-1 we regain the Metropolis algorithm and for E0=1E_0=1 we regain the Wolff algorithm. For −1<E0<1-1<E_0<1, we show that the mean size of the clusters of (possibly) turned spins initially grows with the linear size of the lattice, LL, but eventually saturates at a given lattice size L~\widetilde{L}, which depends on E0E_0. For L>L~L>\widetilde{L}, the Niedermayer algorithm is equivalent to the Metropolis one, i.e, they have the same dynamic exponent. For E0>1E_0>1, the autocorrelation time is always greater than for E0=1E_0=1 (Wolff) and, more important, it also grows faster than a power of LL. Therefore, we show that the best choice of cluster algorithm is the Wolff one, when compared to the Nierdermayer generalization. We also obtain the dynamic behavior of the Wolff algorithm: although not conclusive, we propose a scaling law for the dependence of the autocorrelation time on LL.Comment: Accepted for publication in Journal of Statistical Mechanics: Theory and Experimen
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