Search

The apparent finding of a 125 GeV light Higgs boson would close the minimal Standard Model (SM), that is weakly interacting. This is an exceptional feature not generally true if new physics exists beyond the mass gap found at the LHC up to 700 GeV. Any such new physics would induce departures from the SM in the low-energy dynamics for the minimal electroweak symmetry-breaking sector (EWSBS), with three Goldstone bosons (related to longitudinal W and Z bosons) and one light Higgs-like scalar. With no new particle content, for most of the parameter space, the scattering is actually strongly interacting (with the SM a remarkable exception). We therefore explore various unitarization methods, that have already be applied to the tree-level WL WL amplitude; we find and study a natural second sigma-like scalar pole there. Of note is its appearance due to either elastic or coupled-channel dynamics, especially since the later is largely unconstrained by current LHC data and could be large. [ABSTRACT FROM AUTHOR]

The recent proposal of theories with compactified large extra dimensions is reviewed. We pay especial attention to brane world models with low tension where the only relevant degrees of freedom at low energies are the Standard Model (SM) particles and the branons, which are transversal brane oscillations. By using an effective Lagrangian, we study some phenomenological consequences of these scenarios in a model independent way. [ABSTRACT FROM AUTHOR]

We report on our recent work about the description of a meson gas below the chiral phase transition within the framework of Chiral Perturbation Theory. As an alternative to the standard treatment, we present a calculation of the quark condensate which combines the virial expansion and the meson-meson scattering data. We have also calculated the full one-loop elastic pion scattering amplitude at finite temperature and we have unitarized the amplitude using the Inverse Amplitude Method in order to reproduce the temperature effects on the mass and width of the ρ and σ resonances. Our results show a clear increase of the thermal ρ width, as expected from previous analysis. The results for the σ are consistent with Chiral Symmetry Restoration. We comment on the relevance of our results within the context of Relativistic Heavy Ion Collisions. [ABSTRACT FROM AUTHOR]

If the present dark matter (DM) in the Universe annihilates into Standard Model (SM) particles, it must contribute to the gamma ray fluxes that are detected on the Earth. The magnitude of such contribution depends on the particular DM candidate, but certain features of these spectra may be analyzed in a model-independent fashion. In this work we provide the fitting formula valid for the simulated photon spectra from WIMP annihilation into light quark-anti quark (qq) channels in a wide range of WIMP masses. We illustrate our results for the cc channel. [ABSTRACT FROM AUTHOR]

The viscosity over entropy density ratio, or KSS number, can help isolate the critical point in the hadron phase-diagram in Relativistic Heavy Ion Collisions. We argue that this quantity does have a minimum at a phase transition or crossover. Although indications from conventional non-relativistic gases point out to even a divergence in η/s when the phase-transition is first-order, since the critical exponent is rather low, this will be more difficult to ascertain in RHIC or FAIR. The experimental data are more likely to reveal a discontinuity for a first order phase transition or a smooth minimum at a crossover. [ABSTRACT FROM AUTHOR]

We calculate the bulk viscosity of a pion gas at low energies within the kinetic theory approach and show the importance of dealing properly with the zero modes of this transport coefficient. [ABSTRACT FROM AUTHOR]