Meissner masses in the gCFL phase of QCD

We calculate the Meissner masses of gluons in neutral three-flavor color superconducting matter for finite strange quark mass. In the CFL phase the eissner masses are slowly varying function of the strange quark mass. For large strange quark mass, in the so called gCFL phase, the Meissner masses of gluons with colors $a=1,2,3$ and 8 become imaginary, indicating an instability.Comment: New Fig. 1 shows that also the masses of the gluons 3 and 8 are imaginar

Critical Endpoint and Inverse Magnetic Catalysis for Finite Temperature and Density Quark Matter in a Magnetic Background

In this article we study chiral symmetry breaking for quark matter in a magnetic background, $\bm B$, at finite temperature and quark chemical potential, $\mu$, making use of the Ginzburg-Landau effective action formalism. As a microscopic model to compute the effective action we use the renormalized quark-meson model. Our main goal is to study the evolution of the critical endpoint, ${\cal CP}$, as a function of the magnetic field strength, and investigate on the realization of inverse magnetic catalysis at finite chemical potential. We find that the phase transition at zero chemical potential is always of the second order; for small and intermediate values of $\bm B$, ${\cal CP}$ moves towards small $\mu$, while for larger $\bm B$ it moves towards moderately larger values of $\mu$. Our results are in agreement with the inverse magnetic catalysis scenario at finite chemical potential and not too large values of the magnetic field, while at larger $\bm B$ direct magnetic catalysis sets in.Comment: 6 pages, 2 figure

Comparing electroweak data with a decoupling model

Present data, both from direct Higgs search and from analysis of electroweak data, are starting to become rather restrictive on the possible values for the mass of the standard model Higgs. We discuss a new physics scenario based on a model with decoupling (both in a linear and in a non linear version) showing how it allows for an excellent fit to the present values of the $\epsilon$ parameters and how it widens the allowed ranges for the Higgs mass (thought as elementary in the linear version, or as composite in the non linear one).Comment: 10 pages, 3 Figures Late

Acid Precipitation and Catastrophes in Forest Dynamics: A Conceptual Framework

The focus of this paper will be on the intrinsic nonlinear nature of the vegetation response to acid precipitation, which plays a principal role in causing catastrophes in forest dynamics. We contemplate three possible mechanisms of forest disruption from acidic deposition: (i) through direct effects upon vegetation (such as physical damage to tissues), (ii) through increased soil acidity, which inter alia entails the release of toxic amounts of aluminum and manganese, (iii) through accumulation in the tree biomass of excessive amounts of nutrients, which may be harmful to the plants. We analyze the three corresponding modes of forest decline and demonstrate, within the framework of catastrophe theory, that the second and third mechanisms give rise to a so-called fold catastrophe