Results 1 - 10 of 3360
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[en] We provide a closed analytical form for the gauge contribution to the beta function of a generic Yukawa coupling in the limit of large , where is the number of heavy vector-like fermions charged under an abelian or non-abelian gauge group. The resummed expression is finite and for the abelian case presents a pole at the same location as for the corresponding gauge beta function. When applied to new physics scenarios characterized by large Yukawa couplings, the contribution calculated here can cure their pathological UV behavior and make the couplings asymptotically free.
[en] We extend the already existing two-loop calculation of the effective bottom-Yukawa coupling in the MSSM. In addition to the resummation of the dominant corrections for large values of tg , we include the subleading terms related to the trilinear Higgs coupling A and contributions induced by the electroweak gauge couplings. This calculation has been extended to the NNLO corrections to the MSSM strange-Yukawa coupling. Our analysis leads to residual theoretical uncertainties of the effective Yukawa couplings at the per-cent level.
[en] The light-front Hamiltonian for Yukawa-type models is determined without the framework of canonical light-front formalism. Special attention is paid to the contribution of zero modes. We find that zero modes lead to additional contributions in comparison with the naive canonical light-front Hamiltonian. The structure of such terms is discussed in detail. (author)
[en] Complete text of publication follows. We have performed highly accurate large-scale Molecular Dynamics simulations for the equilibrium dynamics of a single component fluid with Yukawa interaction potential v(r) = q2 exp(-r/λs)/r. We use our numerical results to investigate the domain of validity of the hydrodynamic description, and determine how this depends on the coupling parameter Γ and screening parameter κ = a/λs (a is the mean interparticle distance) that characterise the system. We find, remarkably, that the screening parameter completely determines the maximum wavenumber kmax at which the hydrodynamic description is applicable by kmax λs 0.43 (see Fig. 1). In the extreme case of the Coulomb interaction potential (λs = ∞, κ = 0), the very existence of a hydrodynamic description is a known but unsolved problem. For this important special case, we show that the ordinary hydrodynamic description is never valid. Finally we investigate the system dynamics at wavevectors beyond the validity of conventional hydrodynamics (larger than kmax); we show that these are in striking agreement with a simple generalisation of the Navier-Stokes equations (see Fig. 2). Our results have significant applicability for both analyzing and interpreting the results of x-ray scattering experiments on dense plasmas.
[en] The event excess reported by CMS and ATLAS collaborations from difotonic and ζζ* → 4l channels allow a signal discrimination at regime between 125-126 GeV. This result could open a new window in the Extender Higgs Sector applicability like phenomenological implications of Two Higgs Doublet Model (2HDM) even with its possible incoming strong experimental constraints. There are two phenomenological extreme regimes on 2HDM that could still be compatible with data: the decoupling limit and the scalar degenerate mass spectrum. The first one is based in the supposition that the lightest scalar Higgs has the same couplings than minimal Higgs while the other Higgs reside ar energy scale higher than the electroweak cut (i.e ΛEW << Λ2H D M). In the second one, all neutral Higgs have similar mass values (e.g mho ∼≅ mh2 ∼≅ mAo with sin(β - α) ∼≅ 1) which approximately reproduce observed data and the signal from γ γ and four leptons channels. For this parameter region, we study in CP-conserving frame the behavior of Yukawa sector in 2HDM type I, II and III through f f- → W+W- processes at tree level. For 2HDM-III, we make a discrimination between diagonal Yukawa couplings with aim to analyze their influence in Flavor Changing Neutral Currents processes and their behavior between the CP-even scalar Higgs. (Author)