48,084 research outputs found
Thermodynamics of lattice QCD with 2 flavours of colour-sextet quarks: A model of walking/conformal Technicolor
QCD with two flavours of massless colour-sextet quarks is considered as a
model for conformal/walking Technicolor. If this theory possess an infrared
fixed point, as indicated by 2-loop perturbation theory, it is a
conformal(unparticle) field theory. If, on the other hand, a chiral condensate
forms on the weak-coupling side of this would-be fixed point, the theory
remains confining. The only difference between such a theory and regular QCD is
that there is a range of momentum scales over which the coupling constant runs
very slowly (walks). In this first analysis, we simulate the lattice version of
QCD with two flavours of staggered quarks at finite temperatures on lattices of
temporal extent and 6. The deconfinement and chiral-symmetry
restoration couplings give us a measure of the scales associated with
confinement and chiral-symmetry breaking. We find that, in contrast to what is
seen with fundamental quarks, these transition couplings are very different.
for each of these transitions increases significantly from
and as expected for the finite temperature transitions of an
asymptotically-free theory. This suggests a walking rather than a conformal
behaviour, in contrast to what is observed with Wilson quarks. In contrast to
what is found for fundamental quarks, the deconfined phase exhibits states in
which the Polyakov loop is oriented in the directions of all three cube roots
of unity. At very weak coupling the states with complex Polyakov loops undergo
a transition to a state with a real, negative Polyakov loop.Comment: 21 pages, 9 figures, Revtex with postscript figures. One extra
reference was added; text is unchanged. Corrected typographical erro
Observation of Andreev Surface Bound States in the 3-K phase Region of Sr_2RuO_4
The tunneling spectrum of the superconducting phase with T_c ~ 3.0 K has been
measured in the Ru-embedded region of Sr_2RuO_4 using cleaved junctions. A
sharp zero-bias conductance peak (ZBCP) has been observed below 3 K. All
characteristics of this ZBCP suggest that it originates from Andreev surface
bound states, indicating that the pairing in the 3-K phase is also non-s-wave.
Below the bulk T_c of Sr_2RuO_4 (~1.5 K), a bell-shaped ZBCP was found. This
supports that there is a phase transition in the 3-K phase region near the bulk
T_c.Comment: 4 pages, to appear in Phys. Rev. Lett. 87 (2001
Memory based on abstraction for dynamic fitness functions
Copyright @ Springer-Verlag Berlin Heidelberg 2008.This paper proposes a memory scheme based on abstraction for evolutionary algorithms to address dynamic optimization problems. In this memory scheme, the memory does not store good solutions as themselves but as their abstraction, i.e., their approximate location in the search space. When the environment changes, the stored abstraction information is extracted to generate new individuals into the population. Experiments are carried out to validate the abstraction based memory scheme. The results show the efficiency of the abstraction based memory scheme for evolutionary algorithms in dynamic environments.This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant No. EP/E060722/1
Spin squeezing: transforming one-axis-twisting into two-axis-twisting
Squeezed spin states possess unique quantum correlation or entanglement that
are of significant promises for advancing quantum information processing and
quantum metrology. In recent back to back publications [C. Gross \textit{et al,
Nature} \textbf{464}, 1165 (2010) and Max F. Riedel \textit{et al, Nature}
\textbf{464}, 1170 (2010)], reduced spin fluctuations are observed leading to
spin squeezing at -8.2dB and -2.5dB respectively in two-component atomic
condensates exhibiting one-axis-twisting interactions (OAT). The noise
reduction limit for the OAT interaction scales as , which
for a condensate with atoms, is about 100 times below standard
quantum limit. We present a scheme using repeated Rabi pulses capable of
transforming the OAT spin squeezing into the two-axis-twisting type, leading to
Heisenberg limited noise reduction , or an extra 10-fold
improvement for .Comment: 4 pages, 3 figure
Infrastructure Model Development to Enhance Resilience against future changes using InfraWorks & GIS
The Smart City idea is becoming more popular because cities are getting too crowded. This study looks at how BIM and Geographical Information Systems (GIS) work together. The study focused on infrastructure and figuring out how long a building would last, as early stages of infrastructure development would help the public organization to better plan and design. The GIS mapping shows which areas are more likely to become cities or towns. The AEC industry stakeholders can benefit from mapping to achieve Sustainable Development Goals (SGDs). The AEC industry has also been constantly moving towards Building Information Modelling (BIM). In this study, the city of London was considered, and Land Cover predictions from 2000 to 2025 were made. The predicted Map of 2025 would help developers and planning authorities on decision making on housing development. Based on the current study, more research could be extended on how BIM and GIS could work together for urban development
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