201 research outputs found
Stability of homogeneous chiral phases against inhomogeneous perturbations in 2+1 dimensions
In this work, inhomogeneous chiral phases are studied in a variety of
Four-Fermion and Yukawa models in dimensions at zero and non-zero
temperature and chemical potentials. Employing the mean-field approximation, we
do not find indications for an inhomogeneous phase in any of the studied
models. We show that the homogeneous phases are stable against inhomogeneous
perturbations. At zero temperature, full analytic results are presented.Comment: 10 pages, 1 figure, contains ancillary files with plot data; talk
given at the 39th International Symposium on Lattice Field theory (LATTICE
2022) in Bonn; August 8-13 202
Phase diagram of the 2+1-dimensional Gross-Neveu model with chiral imbalance
In this work, the phase diagram of the -dimensional Gross-Neveu model is
investigated with baryon chemical potential as well as chiral chemical
potential in the mean-field approximation. We study the theory using two
lattice discretizations, which are both based on naive fermions. An
inhomogeneous chiral phase is observed only for one of the two discretizations.
Our results suggest that this phase disappears in the continuum limit.Comment: 9 pages, 2 figures, contains ancillary files with plot data; talk
given at the 38th International Symposium on Lattice Field theory (LATTICE
2021); July 26-30 202
Pathways and roles of wall teichoic acid glycosylation in <i>Staphylococcus aureus</i>
The thick peptidoglycan layers of Gram-positive bacteria are connected to polyanionic glycopolymers called wall teichoic acids (WTA). Pathogens such as Staphylococcus aureus, Listeria monocytogenes, or Enterococcus faecalis produce WTA with diverse, usually strain-specific structure. Extensive studies on S. aureus WTA mutants revealed important functions of WTA in cell division, growth, morphogenesis, resistance to antimicrobials, and interaction with host or phages. While most of the S. aureus WTA-biosynthetic genes have been identified it remained unclear for long how and why S. aureus glycosylates WTA with alpha or beta-linked N-acetylglucosamine (GlcNAc). Only recently the discovery of two WTA glycosyltransferases, TarM and TarS, yielded fundamental insights into the roles of S. aureus WTA glycosylation. Mutants lacking WTA GlcNAc are resistant towards most of the S. aureus phages and, surprisingly, TarS-mediated WTA beta-O-GlcNAc modification is essential for beta-lactam resistance in methicillin-resistant S. aureus. Notably, S. aureus WTA GlcNAc residues are major antigens and activate the complement system contributing to opsonophagocytosis. WTA glycosylation with a variety of sugars and corresponding glycosyltransferases were also identified in other Gram-positive bacteria, which paves the way for detailed investigations on the diverse roles of WTA modification with sugar residues. (C) 2013 Elsevier GmbH. All rights reserved
Detecting inhomogeneous chiral condensation from the bosonic two-point function in the -dimensional Gross-Neveu model in the mean-field approximation
The phase diagram of the -dimensional Gross-Neveu model is
reanalyzed for (non-)zero chemical potential and (non-)zero temperature within
the mean-field approximation. By investigating the momentum dependence of the
bosonic two-point function, the well-known second-order phase transition from
the symmetric phase to the so-called inhomogeneous phase is
detected. In the latter phase the chiral condensate is periodically varying in
space and translational invariance is broken. This work is a proof of concept
study that confirms that it is possible to correctly localize second-order
phase transition lines between phases without condensation and phases of
spatially inhomogeneous condensation via a stability analysis of the
homogeneous phase. To complement other works relying on this technique, the
stability analysis is explained in detail and its limitations and successes are
discussed in context of the Gross-Neveu model. Additionally, we present
explicit results for the bosonic wave-function renormalization in the
mean-field approximation, which is extracted analytically from the bosonic
two-point function. We find regions -- a so-called moat regime -- where the
wave function renormalization is negative accompanying the inhomogeneous phase
as expected.Comment: 27 pages (main text 20, appendix 7), 2 tables, 13 figures (plot data
included in arXiv source file); Updated, published versio
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