5,546 research outputs found
Poisson Brackets, Strings and Membranes
We construct Poisson brackets at boundaries of open strings and membranes
with constant background fields which are compatible with their boundary
conditions. The boundary conditions are treated as primary constraints which
give infinitely many secondary constraints. We show explicitly that we need
only two (the primary one and one of the secondary ones) constraints to
determine Poisson brackets of strings. We apply this to membranes by using
canonical transformations.Comment: 9 pages, references and a note are added, title and abstract is
changed, the section 3 is improved, the version to appear in EPJ
Plasma chemistry and organic synthesis
The characteristic features of chemical reactions using low temperature plasmas are described and differentiated from those seen in other reaction systems. A number of examples of applications of plasma chemistry to synthetic reactions are mentioned. The production of amino acids by discharge reactions in hydrocarbon-ammonia-water systems is discussed, and its implications for the origins of life are mentioned
K^*(BG) rings for groups of order 32
B. Schuster \cite{SCH1} proved that the 2 Morava -theory
is evenly generated for all groups of order 32. For the four
groups with the numbers 38, 39, 40 and 41 in the Hall-Senior list \cite{H},
the ring has been shown to be generated as a -module by
transferred Euler classes. In this paper, we show this for arbitrary and
compute the ring structure of . Namely, we show that
is the quotient of a polynomial ring in 6 variables over by an
ideal for which we list explicit generators.Comment: 23 page
Reentrant topological transitions with Majorana end states in 1D superconductors by lattice modulation
The possibility to observe and manipulate Majorana fermions as end states of
one-dimensional topological superconductors has been actively discussed
recently. In a quantum wire with strong spin-orbit coupling placed in proximity
to a bulk superconductor, a topological superconductor has been expected to be
realized when the band energy is split by the application of a magnetic field.
When a periodic lattice modulation is applied multiple topological
superconductor phases appear in the phase diagram. Some of them occur for
higher filling factors compared to the case without the modulation. We study
the effects of phase jumps and argue that the topologically nontrivial state of
the whole system is retained even if they are present. We also study the effect
of the spatial modulation in the hopping parameter.Comment: 10 pages, 9 figures, submitted to Phys. Rev.
Reentrant topological transitions in a quantum wire/superconductor system with quasiperiodic lattice modulation
We study the condition for a topological superconductor (TS) phase with end
Majorana fermions to appear when a quasiperiodic lattice modulation is applied
to a one-dimensional quantum wire with strong spin-orbit interaction situated
under a magnetic field and in proximity to a superconductor. By density-matrix
renormalization group analysis, we find that multiple topological phases with
Majorana end modes are realized in finite ranges of the filling factor, showing
a sequence of reentrant transitions as the chemical potential is tuned. The
locations of these phases reflect the structure of bands in the non-interacting
case, which exhibits a distinct self-similar structure. The stability of the TS
in the presence of an on-site interaction or a harmonic trap potential is also
discussed.Comment: 5 pages, 4 figures, v4: minor corrections; published in Phys. Rev. B
Rapid Communicatio
Drag dynamics in one-dimensional Fermi systems
We study drag dynamics of several fermions in a fermion cloud in
one-dimensional continuous systems, with particular emphasis on the non-trivial
quantum many-body effects in systems whose parameters change gradually in real
time. We adopt the Fermi--Hubbard model and the time-dependent density matrix
renormalization group method to calculate the drag force on a trapped fermion
cluster in a cloud of another fermion species with contact interaction. The
simulation result shows that a non-trivial peak in the resistance force is
observed in the high cloud density region, which implies a criterion of
effective ways in diffusive transport in a fermion cloud. We compare the DMRG
simulation result with a mean-field result, and it is suggested that some
internal degrees of freedom have a crucial role in the excitation process when
the cloud density is high. This work emphasizes the difference between the
full-quantum calculation and the semiclassical calculation, which is the
quantum effects, in slow dynamics of many-body systems bound in a fermion
cloud.Comment: 7 pages, 8 figure
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