21 research outputs found
Mesons at finite baryon density in (2+1)d
We discuss the critical properies of the three-dimensional Gross-Neveu model
at nonzero temperature and nonzero chemical potential. We also present
numerical and analytical results for the in-medium interaction due to scalar
meson exchange. Further, we discuss in-medium modifications of mesonic
dispersion relations and wavefunctions.Comment: 9 pages, 5 figures, Contribution to Workshop on Finite Density QCD at
Nara, Japan, July 10-12 200
Universality in fermionic field theories at finite temperature
We discuss the critical properties of the three-dimensional NJL model at
nonzero temperature. We show that the Z(2)-symmetric model undergoes a second
order phase transition with 2d Ising exponents and its critical region is
suppressed by a factor 1/N^{-0.5}. We also provide numerical evidence that the
U(1)-symmetric model undergoes a BKT transition in accordance with the
dimensional reduction scenario.Comment: 5 pages, Contribution to Conference on Strong and Electroweak Matter
(SEWM2002), Heidelberg, Germany, 2-5 Oct. 200
Simulating Brain Tumor Heterogeneity with a Multiscale Agent-Based Model: Linking Molecular Signatures, Phenotypes and Expansion Rate
We have extended our previously developed 3D multi-scale agent-based brain
tumor model to simulate cancer heterogeneity and to analyze its impact across
the scales of interest. While our algorithm continues to employ an epidermal
growth factor receptor (EGFR) gene-protein interaction network to determine the
cells' phenotype, it now adds an explicit treatment of tumor cell adhesion
related to the model's biochemical microenvironment. We simulate a simplified
tumor progression pathway that leads to the emergence of five distinct glioma
cell clones with different EGFR density and cell 'search precisions'. The in
silico results show that microscopic tumor heterogeneity can impact the tumor
system's multicellular growth patterns. Our findings further confirm that EGFR
density results in the more aggressive clonal populations switching earlier
from proliferation-dominated to a more migratory phenotype. Moreover, analyzing
the dynamic molecular profile that triggers the phenotypic switch between
proliferation and migration, our in silico oncogenomics data display spatial
and temporal diversity in documenting the regional impact of tumorigenesis, and
thus support the added value of multi-site and repeated assessments in vitro
and in vivo. Potential implications from this in silico work for experimental
and computational studies are discussed.Comment: 37 pages, 10 figure
Evidence for a BKT transition and a pseudogap phase in three-dimensional Gross-Neveu model at nonzero temperature
We present results from Monte Carlo simulations of the three-dimensional
Gross-Neveu model with a U(1) chiral symmetry at nonzero temperature. We
provide evidence that the model undergoes a Berezinskii-Kosterlitz-Thouless
transition in accordance with the dimensional reduction scenario. We also
identify a regime in the high temperature phase in which the fermions acquire
nonzero dynamical mass, analogous to the pseudogap behaviour observed in
cuprate superconductors.Comment: 3 pages, 3 figures, Lattice2001(hightemp
The Logarithmic Triviality of Compact QED Coupled to a Four Fermi Interaction
This is the completion of an exploratory study of Compact lattice Quantum
Electrodynamics with a weak four-fermi interaction and four species of massless
fermions. In this formulation of Quantum Electrodynamics massless fermions can
be simulated directly and Finite Size Scaling analyses can be performed at the
theory's chiral symmetry breaking critical point. High statistics simulations
on lattices ranging from to yield the equation of state, critical
indices, scaling functions and cumulants. The measurements are well fit with
the orthodox hypothesis that the theory is logarithmically trivial and its
continuum limit suffers from Landau's zero charge problem.Comment: 27 pages, 15 figues and 10 table
The scaling region of the lattice O(N) sigma model at finite temperature
We present results from numerical studies of the finite temperature phase
transition of the O(N)-symmetric non-linear sigma model for
and 3. We study the dependence of the width of the 3d critical region on
and we show that the broken phase scaling region is much wider for N=2 and 3
than for N=1. We also compare the widths of the critical region in the low
and high phases of the O(2) model and we show that the scaling region in
the broken phase is much wider than in the symmetric phase. We also report
results for the width of the scaling regions in the low phase
Ising model and we show that the spatial correlation length has to be
approximately twice the lattice temporal extent before the 2d scaling region is
reached.Comment: 17 pages, 7 figure
Failure of Mean Field Theory at Large N
We study strongly coupled lattice QCD with colors of staggered fermions
in 3+1 dimensions. While mean field theory describes the low temperature
behavior of this theory at large , it fails in the scaling region close to
the finite temperature second order chiral phase transition. The universal
critical region close to the phase transition belongs to the 3d XY universality
class even when becomes large. This is in contrast to Gross-Neveu models
where the critical region shrinks as (the number of flavors) increases and
mean field theory is expected to describe the phase transition exactly in the
limit of infinite . Our work demonstrates that close to second order phase
transitions infrared fluctuations can sometimes be important even when is
strictly infinite.Comment: 4 pages, 3 figure