105 research outputs found
The momentum analyticity of two-point correlators from perturbation theory and AdS/CFT
The momentum plane analyticity of two point function of a relativistic
thermal field theory at zero chemical potential is explored. A general
principle regarding the location of the singularities is extracted. In the case
of the N=4 supersymmetric Yang-Mills theory at large , a qualitative
change in the nature of the singularity (branch points versus simple poles)
from the weak coupling regime to the strong coupling regime is observed with
the aid of the AdS/CFT correspondence.Comment: 18 pages, 3 figures, typos fixed, 1 figure update
Enhanced roughness of lipid membranes caused by external electric fields
The behavior of lipid membranes in the presence of an external electric field
is studied and used to examine the influence of such fields on membrane
parameters such as roughness and show that for a micro sized membrane,
roughness grows as the field increases. The dependence of bending rigidity on
the electric field is also studied and an estimation of thickness of the
accumulated charges around lipid membranes in a free-salt solution is
presented.Comment: 9 pages, 6 figures, to appear in Computational Materials Scienc
Supersymmetric Chern-Simons Theories with Vector Matter
In this paper we discuss SU(N) Chern-Simons theories at level k with both
fermionic and bosonic vector matter. In particular we present an exact
calculation of the free energy of the N=2 supersymmetric model (with one chiral
field) for all values of the 't Hooft coupling in the large N limit. This is
done by using a generalization of the standard Hubbard-Stratanovich method
because the SUSY model contains higher order polynomial interactions.Comment: 46 pages, 24 figures, v2: comments and references added, v3: a
footnote in Section 3.5 adde
Three-loop HTL gluon thermodynamics at intermediate coupling
We calculate the thermodynamic functions of pure-glue QCD to three-loop order
using the hard-thermal-loop perturbation theory (HTLpt) reorganization of
finite temperature quantum field theory. We show that at three-loop order
hard-thermal-loop perturbation theory is compatible with lattice results for
the pressure, energy density, and entropy down to temperatures .
Our results suggest that HTLpt provides a systematic framework that can used to
calculate static and dynamic quantities for temperatures relevant at LHC.Comment: 24 pages, 13 figs. 2nd version: improved discussion and fixing typos.
Published in JHE
The order of the quantum chromodynamics transition predicted by the standard model of particle physics
We determine the nature of the QCD transition using lattice calculations for
physical quark masses. Susceptibilities are extrapolated to vanishing lattice
spacing for three physical volumes, the smallest and largest of which differ by
a factor of five. This ensures that a true transition should result in a
dramatic increase of the susceptibilities.No such behaviour is observed: our
finite-size scaling analysis shows that the finite-temperature QCD transition
in the hot early Universe was not a real phase transition, but an analytic
crossover (involving a rapid change, as opposed to a jump, as the temperature
varied). As such, it will be difficult to find experimental evidence of this
transition from astronomical observations.Comment: 7 pages, 4 figure
Once more on the Witten index of 3d supersymmetric YM-CS theory
The problem of counting the vacuum states in the supersymmetric 3d
Yang-Mills-Chern-Simons theory is reconsidered. We resolve the controversy
between its original calculation by Witten at large volumes and the calculation
based on the evaluation of the effective Lagrangian in the small volume limit.
We show that the latter calculation suffers from uncertainties associated with
the singularities in the moduli space of classical vacua where the
Born-Oppenheimer approximation breaks down. We also show that these
singularities can be accurately treated in the Hamiltonian Born-Oppenheimer
method, where one has to match carefully the effective wave functions on the
Abelian valley and the wave functions of reduced non-Abelian QM theory near the
singularities. This gives the same result as original Witten's calculation.Comment: 27 page
Precision SU(3) lattice thermodynamics for a large temperature range
We present the equation of state (pressure, trace anomaly, energy density and
entropy density) of the SU(3) gauge theory from lattice field theory in an
unprecedented precision and temperature range. We control both finite size and
cut-off effects. The studied temperature window (0.7...1000 T_c) stretches from
the glueball dominated system into the perturbative regime, which allows us to
discuss the range of validity of these approaches. We also determine the
preferred renormalization scale of the Hard Thermal Loop scheme and we fit the
unknown g^6 order perturbative coefficient at extreme high temperatures T>100
T_c. We furthermore quantify the nonperturbative contribution to the trace
anomaly using a simple functional form. Our high precision data allows one to
have a complete theoretical description of the equation of state from T=0 all
the way to the phase transition, through the transition region into the
perturbative regime up to the Stefan-Boltzmann limit. We will discuss this
description, too.Comment: 17 pages, 11 figures, tabulated results included. Version accepted
for publication in JHE
Centre symmetric 3d effective actions for thermal SU(N) Yang-Mills from strong coupling series
We derive three-dimensional, Z(N)-symmetric effective actions in terms of
Polyakov loops by means of strong coupling expansions, starting from thermal
SU(N) Yang-Mills theory in four dimensions on the lattice. An earlier action in
the literature, corresponding to the (spatial) strong coupling limit, is thus
extended by several higher orders, as well as by additional interaction terms.
We provide analytic mappings between the couplings of the effective theory and
the parameters of the original thermal lattice theory, which can
be systematically improved. We then investigate the deconfinement transition
for the cases SU(2) and SU(3) by means of Monte Carlo simulations of the
effective theory. Our effective models correctly reproduce second order 3d
Ising and first order phase transitions, respectively. Furthermore, we
calculate the critical couplings and find agreement with
results from simulations of the 4d theory at the few percent level for
.Comment: 27 pages, 21 figures; final version published in JHEP; attached the
corresponding Erratum (ref. JHEP 1107:014,2011, DOI 10.1007/JHEP07(2011)014)
for ease of consultatio
Two-color QCD via dimensional reduction
We study the thermodynamics of two-color QCD at high temperature and/or
density using a dimensionally reduced superrenormalizable effective theory,
formulated in terms of a coarse grained Wilson line. In the absence of quarks,
the theory is required to respect the Z(2) center symmetry, while the effects
of quarks of arbitrary masses and chemical potentials are introduced via soft
Z(2) breaking operators. Perturbative matching of the effective theory
parameters to the full theory is carried out explicitly, and it is argued how
the new theory can be used to explore the phase diagram of two-color QCD.Comment: 17 pages, 1 eps figure, jheppub style; v2: minor update, references
added, published versio
Patterns and partners within the QCD phase diagram including strangeness
We review the current situation of the pattern of chiral symmetry
restoration. In particular, we analyze partner degeneration for and
symmetries within the context of Ward Identities and Effective
Theories. The application of Ward Identities to the thermal scaling of
screening masses is also discussed. We present relevant observables for which
an Effective Theory description in terms of Chiral Perturbation Theory and its
unitarized extension are compatible with lattice data even around the
transition region. We pay special attention to the role of strangeness in this
context.Comment: Proceedings of the Workshop "Strangeness in Quark Matter 2019", 6
pages, 2 figure
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