5,703 research outputs found
Excited light and strange hadrons from the lattice with two Chirally Improved quarks
Results for excited light and strange hadrons from the lattice with two
flavors of Chirally Improved sea quarks are presented. We perform simulations
at several values of the pion mass ranging from 250 to 600 MeV and extrapolate
to the physical pion mass. The variational method is applied to extract excited
energy levels but also to discuss the content of the states. Among others, we
explore the flavor singlet/octet content of Lambda states. In general, our
results agree well with experiment, in particular we confirm the Lambda(1405)
and its dominant flavor singlet structure.Comment: Contribution to the XV International Conference on Hadron
Spectroscopy "Hadron 2013", 4-8 November 2013, Nara, Japa
A Backtracking-Based Algorithm for Computing Hypertree-Decompositions
Hypertree decompositions of hypergraphs are a generalization of tree
decompositions of graphs. The corresponding hypertree-width is a measure for
the cyclicity and therefore tractability of the encoded computation problem.
Many NP-hard decision and computation problems are known to be tractable on
instances whose structure corresponds to hypergraphs of bounded
hypertree-width. Intuitively, the smaller the hypertree-width, the faster the
computation problem can be solved. In this paper, we present the new
backtracking-based algorithm det-k-decomp for computing hypertree
decompositions of small width. Our benchmark evaluations have shown that
det-k-decomp significantly outperforms opt-k-decomp, the only exact hypertree
decomposition algorithm so far. Even compared to the best heuristic algorithm,
we obtained competitive results as long as the hypergraphs are not too large.Comment: 19 pages, 6 figures, 3 table
Minimal qubit tomography
We present, and analyze thoroughly, a highly symmetric and efficient scheme
for the determination of a single-qubit state, such as the polarization
properties of photons emitted by a single-photon source. In our scheme there
are only four measured probabilities, just enough for the determination of the
three parameters that specify the qubit state, whereas the standard procedure
would measure six probabilities.Comment: 14 pages, 10 figures; final versio
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Systemic Risk-Shifting in Financial Networks
Banks face different but potentially correlated risks from outside the financial system. Financial connections can share these risks, but also create the means by which shocks can propagate. We examine this tradeoff in the context of a new stylised fact
Spin injection across magnetic/non-magnetic interfaces with finite magnetic layers
We have reconsidered the problem of spin injection across
ferromagnet/non-magnetic-semiconductor (FM/NMS) and
dilute-magnetic-semiconductor/non-magnetic-semiconductor interfaces, for
structures with \textit{finite} magnetic layers (FM or DMS). By using
appropriate physical boundary conditions, we find expressions for the
resistances of these structures which are in general different from previous
results in the literature. When the magnetoresistance of the contacts is
negligible, we find that the spin-accumulation effect alone cannot account for
the dependence observed in recent magnetoresistance data. In a limited
parameter range, our formulas predict a strong dependence arising from the
magnetic contacts in systems where their magnetoresistances are sizable.Comment: 6 pages, 3 eps figs. (extended version- new title + two new figures
added
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