8,181 research outputs found
Renormalization group analysis of the three-dimensional Gross-Neveu model at finite temperature and density
The Renormalization Group flow equations obtained by means of a proper time
regulator are used to analyze the restoration of the discrete chiral symmetry
at non-zero density and temperature in the Gross-Neveu model in d=2+1
dimensions. The effects of the wave function renormalization of the auxiliary
scalar field on the transition have been studied. The analysis is performed for
a number of fermion flavors N_f=12 and the limit of large N_f is also
considered. The results are compared with those coming from lattice
simulations.Comment: Latex file, 12 pages, 2 eps figures, minor changes, added references,
published versio
Localização de espécies florestais nativas em fragmentos da Floresta Ombrófila Mista no território centro-sul do Paraná.
EVINCI. Resumo
Genuine Non-Self-Averaging and Ultra-Slow Convergence in Gelation
In irreversible aggregation processes droplets or polymers of microscopic
size successively coalesce until a large cluster of macroscopic scale forms.
This gelation transition is widely believed to be self-averaging, meaning that
the order parameter (the relative size of the largest connected cluster)
attains well-defined values upon ensemble averaging with no sample-to-sample
fluctuations in the thermodynamic limit. Here, we report on anomalous gelation
transition types. Depending on the growth rate of the largest clusters, the
gelation transition can show very diverse patterns as a function of the control
parameter, which includes multiple stochastic discontinuous transitions,
genuine non-self-averaging and ultra-slow convergence of the transition point.
Our framework may be helpful in understanding and controlling gelation.Comment: 8 pages, 10 figure
Search for a SM Higgs boson in the diphoton plus EMISS T channel
In this paper I discuss the search for a Standard Model (SM) Higgs boson in the diphoton plus missing transverse energy (missing ET or EMISS T ) channel using 20.7 fb−1 of data recorded by the ATLAS detector in the year 2012. Higgs
boson at LHC can be generated through different processes: gluon-gluon fusion (∼ 85%), vector boson fusion (∼ 10%), W/Z associated production (∼ 5%) and top-antitop fusion (< 1%). The applied selection is optimized to isolate events from Higgs boson production associated with a W or Z boson requiring the presence of EMISS T from Z/W decay into neutrinos in addition to two isolated energetic photons.
The sensitivity of this analysis is presented and found to be at a level above 5 times the predicted Standard Model cross-section
Majorana Quasi-Particles Protected by Angular Momentum Conservation
We show how angular momentum conservation can stabilise a symmetry-protected
quasi-topological phase of matter supporting Majorana quasi-particles as edge
modes in one-dimensional cold atom gases. We investigate a number-conserving
four-species Hubbard model in the presence of spin-orbit coupling. The latter
reduces the global spin symmetry to an angular momentum parity symmetry, which
provides an extremely robust protection mechanism that does not rely on any
coupling to additional reservoirs. The emergence of Majorana edge modes is
elucidated using field theory techniques, and corroborated by
density-matrix-renormalization-group simulations. Our results pave the way
toward the observation of Majorana edge modes with alkaline-earth-like fermions
in optical lattices, where all basic ingredients for our recipe - spin-orbit
coupling and strong inter-orbital interactions - have been experimentally
realized over the last two years.Comment: 12 pages (6 + 6 supplementary material
Kinks and waterfalls as signatures of competing order in angle-resolved photoemission spectra of La_{2-x}Sr_xCuO_4
We show that the so-called kinks and waterfalls observed in angle-resolved
photoemission spectra of La2-xSrxCuO4, a prototypical high-Tc superconducting
cuprate, result from the coupling of quasiparticles with two distinct nearly
critical collective modes with finite characteristic wave vectors, typical of
charge and spin fluctuations near a stripe instability. Both phonon-like charge
and spin collective modes are needed to account for the kinked quasiparticle
dispersions. This clarifies the long-standing question whether kinks are due to
phonons or spin waves and the nature of the bosonic mediators of the
electron-electron effective interaction in La2-xSrxCuO4.Comment: 5 pages, 4 figure
Wilson Fermions and Axion Electrodynamics in Optical Lattices
The formulation of massless relativistic fermions in lattice gauge theories
is hampered by the fundamental problem of species doubling, namely, the rise of
spurious fermions modifying the underlying physics. A suitable tailoring of the
fermion masses prevents such abundance of species, and leads to the so-called
Wilson fermions. Here we show that ultracold atoms provide us with the first
controllable realization of these paradigmatic fermions, thus generating a
quantum simulator of fermionic lattice gauge theories. We describe a novel
scheme that exploits laser-assisted tunneling in a cubic optical superlattice
to design the Wilson fermion masses. The high versatility of this proposal
allows us to explore a variety of interesting phases in three-dimensional
topological insulators, and to test the remarkable predictions of axion
electrodynamics.Comment: RevTex4 file, color figures, slightly longer than the published
versio
Elaboração de um mapa Ãndice e um sistema de informação geográfica das espécies de interesse.
EVINCI. Resumo
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