2,817 research outputs found
A Unified Conformal Field Theory Description of Paired Quantum Hall States
The wave functions of the Haldane-Rezayi paired Hall state have been
previously described by a non-unitary conformal field theory with central
charge c=-2. Moreover, a relation with the c=1 unitary Weyl fermion has been
suggested. We construct the complete unitary theory and show that it
consistently describes the edge excitations of the Haldane-Rezayi state.
Actually, we show that the unitary (c=1) and non-unitary (c=-2) theories are
related by a local map between the two sets of fields and by a suitable change
of conjugation. The unitary theory of the Haldane-Rezayi state is found to be
the same as that of the 331 paired Hall state. Furthermore, the analysis of
modular invariant partition functions shows that no alternative unitary
descriptions are possible for the Haldane-Rezayi state within the class of
rational conformal field theories with abelian current algebra. Finally, the
known c=3/2 conformal theory of the Pfaffian state is also obtained from the
331 theory by a reduction of degrees of freedom which can be physically
realized in the double-layer Hall systems.Comment: Latex, 42 pages, 2 figures, 3 tables; minor corrections to text and
reference
Solar cell radiation response near the interface of different atomic number materials
The response of cobalt 60 irradiated N/P silicon solar cells was measured as a function of the atomic number of the medium adjacent to the cell and the direction of the gamma ray beam. The interpositioning of various thicknesses of aluminum between the adjacent material and the cell had the effect of moving the cell to various locations in an approximate monatomic numbered medium. Using this technique the solar cell response was determined at various distances from the interface for gold and beryllium. The results were compared with predictions based upon ionization chamber measurements of dose perturbations in aluminum and found to agree within five percent. Ionization chamber data was then used to estimate the influence of various base contact materials
THE SUBURBAN BATHS IN POMPEII: INNOVATIVE STRATEGIES OF CONSERVATION AND DIGITAL HUMANITIES FOR AN IMPROVED USE AND PERCEPTION
Abstract. The paper aims to examine the results of an experimental research on the enlarged fruition and "communication" of Pompeii archeological heritage. The main focus of the research were the Suburban Thermal baths in Pompeii, the ancient Roman city buried during the Vesiuvus volcano eruption in 79 a.C. The Suburban Thermal baths are located within the Insula Occidentalis, a wide area at West of the old city of Pompeii. They have been a special entrance to the archeological site since the rediscovery of the ancient city. The Thermal baths area was neglected for a long time, but then it was included in the conservation project for Porta Marina and the superintendence offices, led by Amedeo Maiuri. However, these measures didn't lead to in-depth, systematic studies, that were to be conducted only during the early '2000. Nowadays, new technologies can be helpful to convey the actual value of the big archeological heritage. In fact, they represent a real asset to show any transformation or restoration work, that made the thermal baths a peculiar, stratified artefact. The historical and artistic information have been reinterpreted in a more technological, contemporary language; therefore, the visitor has the opportunity to experience a more conscious and multilayer reading of the Pompeii thermal complex. In addition, in this paper will be examined new opportunities of collection, analysis and information sharing of the case study. A special focus will vert on how the conscious use of new technologies and storytelling may be the key to understand the material and immaterial traces of the Suburban Thermal baths
Partition Functions, Duality, and the Tube Metric
The partition function of type IIA and B strings on R^6xK3, in the T^4/Z_2
orbifold limit, is explicitly computed as a modular invariant sum over spin
strutures required by perturbative unitarity in order to extend the analysis to
include type II strings on R^6 x W4, where W4 is associated with the tube
metric conformal field theory, given by the degrees of freedom transverse to
the Neveu-Schwarz fivebrane solution. This generates partition functions and
perturbative spectra of string theories in six space-time dimensions,
associated with the modular invariants of the level k affine SU(2) Kac-Moody
algebra. These theories provide a conformal field theory (i.e. perturbative)
probe of non-perturbative (fivebrane) vacua. We contrast them with theories
whose N=(4,4) sigma-model action contains n_H=k+2 hypermultiplets as well as
vector supermultiplets, and where k is the level just mentioned. In Appendix B
we also give a D=6, N=(1,1) `free fermion' string model which has a different
moduli space of vacua from the 81 parameter space relevant to the above
examples.Comment: 24 pages, TE
A note on the topological order of noncommutative Hall fluids
We evaluate the ground state degeneracy of noncommutative Chern-Simons models
on the two-torus, a quantity that is interpreted as the "topological order" of
associated phases of Hall fluids. We define the noncommutative theory via
T-duality from an ordinary Chern-Simons model with non-abelian 't Hooft
magnetic fluxes. Motivated by this T-duality, we propose a discrete family of
noncommutative, non-abelian fluid models, arising as a natural generalization
of the standard noncommutative Chern-Simons effective models. We compute the
topological order for these universality classes, and comment on their possible
microscopic interpretation.Comment: 14 page
Chiral persistent currents and magnetic susceptibilities in the parafermion quantum Hall states in the second Landau level with Aharonov-Bohm flux
Using the effective conformal field theory for the quantum Hall edge states
we propose a compact and convenient scheme for the computation of the periods,
amplitudes and temperature behavior of the chiral persistent currents and the
magnetic susceptibilities in the mesoscopic disk version of the Z_k parafermion
quantum Hall states in the second Landau level. Our numerical calculations show
that the persistent currents are periodic in the Aharonov-Bohm flux with period
exactly one flux quantum and have a diamagnetic nature. In the high-temperature
regime their amplitudes decay exponentially with increasing the temperature and
the corresponding exponents are universal characteristics of non-Fermi liquids.
Our theoretical results for these exponents are in perfect agreement with those
extracted from the numerical data and demonstrate that there is in general a
non-trivial contribution coming from the neutral sector. We emphasize the
crucial role of the non-holomorphic factors, first proposed by Cappelli and
Zemba in the context of the conformal field theory partition functions for the
quantum Hall states, which ensure the invariance of the annulus partition
function under the Laughlin spectral flow.Comment: 14 pages, RevTeX4, 7 figures (eps
Composite Fermion Wavefunctions Derived by Conformal Field Theory
The Jain theory of hierarchical Hall states is reconsidered in the light of
recent analyses that have found exact relations between projected Jain
wavefunctions and conformal field theory correlators. We show that the
underlying conformal theory is precisely given by the W-infinity minimal models
introduced earlier. This theory involves a reduction of the multicomponent
Abelian theory that is similar to the projection to the lowest Landau level in
the Jain approach. The projection yields quasihole excitations obeying
non-Abelian fractional statistics. The analysis closely parallels the bosonic
conformal theory description of the Pfaffian and Read-Rezayi states.Comment: 4 pages, 1 figur
Partition Functions of Non-Abelian Quantum Hall States
Partition functions of edge excitations are obtained for non-Abelian Hall
states in the second Landau level, such as the anti-Read-Rezayi state, the
Bonderson-Slingerland hierarchy and the Wen non-Abelian fluid, as well as for
the non-Abelian spin-singlet state. The derivation is straightforward and
unique starting from the non-Abelian conformal field theory data and solving
the modular invariance conditions. The partition functions provide a complete
account of the excitation spectrum and are used to describe experiments of
Coulomb blockade and thermopower.Comment: 42 pages, 3 figures; published version; minor corrections to sect.
4.
Algae-based biorefinery concept. An LCI analysis for a theoretical plant
Both micro and macro algae have a potential to be a valuable feedstock for biorefineries. The theoretical impact assessment of this kind of plant can be carried out through an LCA, which is a key tool in order to evaluate the potential environmental impact of a process throughout its entire life cycle. Hence, it is a priority to perform an LCI with the aim of gathering all the data and simulating all the unit process of a theoretical biorefinery. The Inventory ensures to obtain a simple and immediate way to represent several aspects of a biorefinery, e.g. productivity, environmental pressures, required resources in terms of raw materials and energy. One of the main aspects clearly shown in this study is the significant environmental pressures due to the cultivation and harvesting steps, for which it is desirable to consider a biomass collection from the environment, especially from areas where eutrophication phenomena are particularly recurrent. Another conclusion drawn from the study is that the total plant production per year appears very limited, if compared to any conventional refinery. The following approach can also provide a starting data set to perform a first approximate economic analysis of the costs/gains of the outlined project, and it could be used as a first concept design for the project development of a real plant
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