1,809 research outputs found
Nonequilibrium functional renormalization group for interacting quantum systems
We propose a nonequilibrium version of functional renormalization within the
Keldysh formalism by introducing a complex valued flow parameter in the Fermi
or Bose functions of each reservoir. Our cutoff scheme provides a unified
approach to equilibrium and nonequilibrium situations. We apply it to
nonequilibrium transport through an interacting quantum wire coupled to two
reservoirs and show that the nonequilibrium occupation induces new power law
exponents for the conductance.Comment: 5 pages, 2 figures; published versio
Leading-logarithmic approximation by one-loop renormalization group within Matsubara formalism
We demonstrate how to devise a Matsubara-formalism based one-loop
approximation to the flow of the functional renormalization group (FRG) that
reproduces identically the leading-logarithmic parquet approximation. This
construction of a controlled fermionic FRG approximation in a regime not
accessible by perturbation theory generalizes a previous study from the
real-time zero-temperature formalism to the Matsubara formalism and thus to the
de facto standard framework used for condensed-matter FRG studies. Our
investigation is based on a simple model for the absorption of x-rays in
metals. It is a core part of our construction to exploit that in a suitable
leading-logarithmic approximation the values of the particle-hole
susceptibility on the real and on the imaginary frequency axis are identical.Comment: 20 pages, 7 figure
The Half-lives of La and La
The half-lives of La and La were determined via gamma
spectroscopy and high-precision ionization chamber measurements. The results
are 18.930(6) h for La and 4.59(4) h for La compared to the
previously compiled values of 19.5(2) h and 4.8(2) h, respectively. The new
results represent an improvement in the precision and accuracy of both values.
These lanthanum isotopes comprise a medically interesting system with positron
emitter La and Auger electron emitter La forming a matched pair
for internal diagnostics and therapeutics. The precise half-lives are necessary
for proper evaluation of their value in medicine and for a more representative
tabulation of nuclear data.Comment: 11 pages, 3 figure
Temperature induced phase averaging in one-dimensional mesoscopic systems
We analyse phase averaging in one-dimensional interacting mesoscopic systems
with several barriers and show that for incommensurate positions an independent
average over several phases can be induced by finite temperature. For three
strong barriers with conductances G_i and mutual distances larger than the
thermal length, we obtain G ~ sqrt{G_1 G_2 G_3} for the total conductance G.
For an interacting wire, this implies power laws in G(T) with novel exponents,
which we propose as an experimental fingerprint to distinguish temperature
induced phase averaging from dephasing.Comment: 6 pages, 5 figures; added one figure; slightly extende
Interlaboratory comparison tests as a tool for quality improvement in fertilizer analysis methods and laboratory performance
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