5,836 research outputs found
Lattice field theory simulations of Dirac semimetals
In this paper the observed Dirac semimetals NaBi and CdAs are
studied within lattice simulation. We formulate lattice field theory with
rooted staggered fermions on anisotropic lattice. It is shown that in the limit
of zero temporal lattice spacing this theory reproduces low energy effective
theory of Dirac semimetals. Using this lattice theory we study the phase
diagram of Dirac semimetals in the plane effective coupling constant--Fermi
velocity anisotropy. Within the formulated theory the results are practically
volume independent in contrast with our previous study. Our results confirm our
previous finding that within the Dirac model with bare Coulomb interaction both
NaBi and CdAs lie deep in the insulator phase.Comment: 11 pages, 5 figures, 2 tables, typo in Eq. (20) corrected, Appendix
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Study of shear viscosity of SU (2)-gluodynamics within lattice simulation
This paper is devoted to the study of two-point correlation function of the
energy-momentum tensor T_{12}T_{12} for SU(2)-gluodynamics within lattice
simulation of QCD. Using multilevel algorithm we carried out the measurement of
the correlation function at the temperature T/T_c = 1.2. It is shown that
lattice data can be described by spectral functions which interpolate between
hydrodynamics at low frequencies and asymptotic freedom at high frequencies.
The results of the study of spectral functions allowed us to estimate the ratio
of shear viscosity to the entropy density {\eta}/s = 0.134 +- 0.057.Comment: 7 pages, 3 figure
Catalysis of Dynamical Chiral Symmetry Breaking by Chiral Chemical Potential in Dirac semimetals
In this paper we study how dynamical chiral symmetry breaking is affected by
nonzero chiral chemical potential in Dirac semimetals. To perform this study we
applied lattice quantum Monte Carlo simulations of Dirac semimetals. Within
lattice simulation we calculated the chiral condensate for various fermion
masses, the chiral chemical potentials and effective coupling constants. For
all parameters under consideration we have found that the chiral condensate is
enhanced by chiral chemical potential. Thus our results confirms that in Dirac
semimetals the chiral chemical potential plays a role of the catalyst of the
dynamical chiral symmetry breaking.Comment: 11 pages, 3 figure
Some features of the fabrication of multilayer fiber composites by explosive welding
The fabrication of multilayer fiber composites by explosive welding is characterized by intense plastic deformation of the matrix material as it fills the spaces between fibers and by high velocity of the collision between matrix layers due to acceleration in the channels between fibers. The plastic deformation of the matrix layers and fiber-matrix friction provide mechanical and thermal activation of the contact surfaces, which contributes to the formation of a bond. An important feature of the process is that the fiber-matrix adhesion strength can be varied over a wide range by varying the parameters of impulsive loading
Observation of deconfinement in a cold dense quark medium
In this paper we study the confinement/deconfinement transition in lattice
QCD at finite quark density and zero temperature. The simulations are
performed on an lattice with rooted staggered fermions at a lattice
spacing . This small lattice spacing allowed us to
reach very large baryon density (up to quark chemical potential ) avoiding strong lattice artifacts. In the region we observe for the first time the confinement/deconfinement
transition which manifests itself in rising of the Polyakov loop and vanishing
of the string tension . After the deconfinement is achieved at , we observe a monotonous decrease of the spatial string
tension which ends up with vanishing at . From this observation we draw the conclusion that the
confinement/deconfinement transition at finite density and zero temperature is
quite different from that at finite temperature and zero density. Our results
indicate that in very dense matter the quark-gluon plasma is in essence a
weakly interacting gas of quarks and gluons without a magnetic screening mass
in the system, sharply different from a quark-gluon plasma at large
temperature.Comment: 6 pages, 4 figure
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