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

Thermodynamics of the Massive Gross-Neveu Model

We study the thermodynamics of massive Gross-Neveu models with explicitly broken discrete or continuous chiral symmetries for finite temperature and fermion densities. The large $N$ limit is discussed bearing attention to the no-go theorems for symmetry breaking in two dimensions which apply to the massless cases. The main purpose of the study is to serve as analytical orientation for the more complex problem of chiral transition in $4-$dimensional QCD with quarks. For any non-vanishing fermion mass we find, at finite densities, lines of first order phase transitions. For small mass values traces of would-be second order transitions and a tricritical point are recognizable. We study the thermodynamics of these models, and in the model with broken continuous chiral symmetry we examine the properties of the pion like state.Comment: 34 pages (+18 figures, available upon request to [email protected]), LATEX file, uses art12a.sty, macro included, UGVA-DPT 1994/06-85

The Jurassic pleurotomarioidean gastropod Laevitomaria and its palaeobiogeographical history

The genus Laevitomaria is reviewed and its palaeobiogeographical history is reconstructed based on the re-examination of its type species L. problematica, the study of material stored at the National Natural History Museum of Luxembourg, and an extensive review of the literature. The systematic study allows ascribing to Laevitomaria a number of Jurassic species from the western European region formerly included in other pleurotomariid genera. The following new combinations are proposed: Laevitomaria allionta, Laevitomaria amyntas, Laevitomaria angulba, Laevitomaria asurai, Laevitomaria daityai, Laevitomaria fasciata, Laevitomaria gyroplata, Laevitomaria isarensis, Laevitomaria joannis, Laevitomaria repeliniana, Laevitomaria stoddarti, Laevitomaria subplatyspira, and Laevitomaria zonata. The genus, which was once considered as endemic of the central part of the western Tethys, shows an evolutionary and palaeogeographical history considerably more complex than previously assumed. It first appeared in the Late Sinemurian in the northern belt of the central western Tethys involved in the Neotethyan rifting, where it experienced a first radiation followed by an abrupt decline of diversity in the Toarcian. Species diversity increased again during Toarcian\u2013Aalenian times in the southernmost part of western European shelf and a major radiation occurred during the Middle Aalenian to Early Bajocian in the northern Paris Basin and southern England. After a latest Bajocian collapse of diversity, Laevitomaria disappeared from both the central part of western Tethys and the European shelf. In the Bathonian, the genus appeared in the south-eastern margin of the Tethys where it lasted until the Oxfordian