42,608 research outputs found
Multichannel charge Kondo effect and non-Fermi liquid fixed points in conventional and topological superconductor islands
We study multiterminal Majorana and conventional superconducting islands in
the vicinity of the charge degeneracy point using bosonization and numerical
renormalization group. Both models map to the multichannel charge Kondo
problem, but for noninteracting normal leads they flow to different non-Fermi
liquid fixed points at low temperatures. We compare and contrast both cases by
numerically obtaining the full crossover to the low temperature regime and
predict distinctive transport signatures. We attribute the differences between
both types of islands to a crucial distinction of charge- and charge-
transfer in the conventional and topological case, respectively. In the
conventional case, our results establish s-wave islands as a new platform to
study the intermediate multichannel Kondo fixed point. In the topological setup
the crossover temperature to non-Fermi liquid behavior is relatively high as it
is proportional to level broadening and the transport results are not sensitive
to channel coupling anisotropy, moving away from the charge degeneracy point or
including a small Majorana hybridization, which makes our proposal
experimentally feasible.Comment: 14 pages, 10 figure
A Model for Donation Verification
In this paper, we introduce a model for donation verification. A randomized
algorithm is developed to check if the money claimed being received by the
collector is -approximation to the total amount money contributed
by the donors. We also derive some negative results that show it is impossible
to verify the donations under some circumstances
Integrated HI emission in galaxy groups and clusters
The integrated HI emission from hierarchical structures such as groups and
clusters of galaxies can be detected by FAST at intermediate redshifts. Here we
propose to use FAST to study the evolution of the global HI content of clusters
and groups over cosmic time by measuring their integrated HI emissions. We use
the Virgo cluster as an example to estimate the detection limit of FAST, and
have estimated the integration time to detect a Virgo type cluster at different
redshifts (from z=0.1 to z=1.5). We have also employed a semi-analytic model
(SAM) to simulate the evolution of HI contents in galaxy clusters. Our
simulations suggest that the HI mass of a Virgo-like cluster could be 2-3 times
higher and the physical size could be more than 50\% smaller when redshift
increases from z=0.3 to z=1. Thus the integration time could be reduced
significantly and gas rich clusters at intermediate redshifts can be detected
by FAST in less than 2 hour of integration time. For the local universe, we
have also used SAM simulations to create mock catalogs of clusters to predict
the outcomes from FAST all sky surveys. Comparing with the optically selected
catalogs derived by cross matching the galaxy catalogs from the SDSS survey and
the ALFALFA survey, we find that the HI mass distribution of the mock catalog
with 20 second of integration time agrees well with that of observations.
However, the mock catalog with 120 second integration time predicts much more
groups and clusters that contains a population of low mass HI galaxies not
detected by the ALFALFA survey. Future deep HI blind sky survey with FAST would
be able to test such prediction and set constraints to the numerical simulation
models. Observational strategy and sample selections for the future FAST
observations of galaxy clusters at high redshifts are also discussed.Comment: 18 pages,5 figure
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