540 research outputs found
The 2-Hilbert Space of a Prequantum Bundle Gerbe
We construct a prequantum 2-Hilbert space for any line bundle gerbe whose
Dixmier-Douady class is torsion. Analogously to usual prequantisation, this
2-Hilbert space has the category of sections of the line bundle gerbe as its
underlying 2-vector space. These sections are obtained as certain morphism
categories in Waldorf's version of the 2-category of line bundle gerbes. We
show that these morphism categories carry a monoidal structure under which they
are semisimple and abelian. We introduce a dual functor on the sections, which
yields a closed structure on the morphisms between bundle gerbes and turns the
category of sections into a 2-Hilbert space. We discuss how these 2-Hilbert
spaces fit various expectations from higher prequantisation. We then extend the
transgression functor to the full 2-category of bundle gerbes and demonstrate
its compatibility with the additional structures introduced. We discuss various
aspects of Kostant-Souriau prequantisation in this setting, including its
dimensional reduction to ordinary prequantisation.Comment: 97 pages; v2: minor changes; Final version to be published in Reviews
in Mathematical Physic
Detailed Phase Transition Study at M_H <= 70 GeV in a 3-dimensional --Higgs Model
We study the electroweak phase transition in an effective 3-dimensional
theory for a Higgs mass of about 70 GeV by Monte Carlo simulations. The
transition temperature and jumps of order parameters are obtained and
extrapolated to the continuum using multi-histogram techniques and finite size
analysis.Comment: Talk presented at LATTICE96(electroweak), 4 pages, 5 figure
Hubbard Model with Luscher fermions - a progress report
Some modifications of the Luscher algorithm, which reduce the autocorelation
time, are proposed and tested.Comment: 3 pages, uuencoded gzipped Postscript, contribution to Lattice 9
Physics of the Electroweak Phase Transition at M_H <= 70 GeV in a 3-dimensional SU(2)-Higgs Model
Physical parameters of the electroweak phase transition in a 3d effective
lattice SU(2)-Higgs model are presented. The phase transition temperatures,
latent heats and continuum condensate discontinuities are measured at Higgs
masses of about 70 and 35 GeV. Masses and Higgs condensates are compared to
perturbation theory in the broken phase. In the symmetric phase bound states
and the static force are determined.Comment: Talk presented at LATTICE96(electroweak), 4 pages, 5 figure
On the scaling of the electroweak interface tension at finite temperature
We determine the interface tension of the finite-temperature electroweak
phase transition in a numerical investigation of the SU(2)--Higgs model on a
four-dimensional lattice with temporal extension . In this simulation
the chosen parameters correspond to a Higgs boson mass of about 16 GeV. As a
result the interface tension shows only small scaling violations in comparison
with previous studies for lattices. We also report on some experiences
with autocorrelations in the applied Monte Carlo simulations of two-phase
systems.Comment: 10 pages, latex2e, 7 Postscript figures, uses packages epsfig and
amssym
Interface Tension of the Electroweak Phase Transition
In our nonperturbative lattice investigation we study the interface tension
of the finite-temperature electroweak phase transition. In this analysis the
Higgs mass has been chosen to be about GeV. At the transition point of a
finite volume system, tunnelling between the symmetric and the Higgs phase
takes place. This phenomenon leads to a splitting of the ground state, which
can be used to determine the interface tension. The result obtained this way
agrees with the result of the two-coupling method and with the prediction of
the perturbative approach.Comment: 10 pages, five figures in uuencoded PS format, Latex + epsf.st
Numerical Simulations and the Strength of the Electroweak Phase Transition
Numerical simulations are performed to study the finite temperature phase
transition in the SU(2) Higgs model on the lattice. The strength of the first
order phase transition is investigated by determining the latent heat and the
interface tension on lattices. The values of the Higgs boson mass
presently chosen are below 50 GeV. Our results are in qualitative agreement
with two-loop resummed perturbation theory.Comment: (Only a few minor changes compared to the original version.) 9 pages
and 2 figures, DESY-94-08
Where does the hot electroweak phase transition end?
We give the nonperturbative phase diagram of the four-dimensional hot
electroweak phase transition. A systematic extrapolation is done. Our
results show that the finite temperature SU(2)-Higgs phase transition is of
first order for Higgs-boson masses GeV. The full
four-dimensional result agrees completely with that of the dimensional
reduction approximation. This fact is of particular importance, because it
indicates that the fermionic sector of the Standard Model (SM) can be included
perturbatively. We obtain that the Higgs-boson endpoint mass in the SM is GeV. Taking into account the LEP Higgs-boson mass lower bound excludes
any electroweak phase transition in the SM.Comment: LATTICE98(electroweak), presented by Z. Fodor. Latex, 3 pages, 3 figu
res. Comment line change
3-D lattice simulation of the electroweak phase transition at small Higgs mass
We study the electroweak phase transition by lattice simulations of an
effective 3-dimensional theory, for a Higgs mass of about . In the
broken symmetry phase our results on masses and the Higgs condensate are
consistent with 2-loop perturbative results. However, we find a
non-perturbative lowering of the transition temperature, similar to the one
previously found at . For the symmetric phase, bound state masses
and the static force are determined and compared with results for pure
theory.Comment: 11 pages, uuencoded ps-file, 5 postscript figures include
Trophic networks improve the performance of microbial anodes treating wastewater
Microbial anodes represent a distinct ecological niche that is characterized mainly by the terminal electron acceptor, i.e., the anode potential, and the substrate, i.e., the electron source. Here, we determine the performance and the biofilm community of anode microbiomes while using substrates of increasing complexity (organic acids or organic acids and sugar or real domestic wastewater) to mimic different, practically relevant, trophic levels. α-Diversity values increased with substrate complexity. In addition, the higher abundance value of Deltaproteobacteria in the biofilms corresponds to higher reactor performance (i.e., COD removal, current density, and Coulombic efficiency). In reactors exploiting real wastewater, the diversity of the planktonic microorganisms was only little affected. Microbiome network analysis revealed two important clusters for reactor performance as well as performance-independent pathogen-containing clusters. Interestingly, Geobacter was not found to be integrated in the network underlining its outstanding individual ecological role in line with its importance for the efficiency of the electron harvest for all reactors. The microbiome analysis of different trophic levels and their temporal development from initial colonization to stable treatment demonstrate important principles for the implementation of microbial anodes for wastewater treatment
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