Multi-Grid Lanczos Clark, M. A.; Jung, Chulwoo; Lehner, Christoph
EPJ Web of Conferences,
01/2018, Volume:
175
Journal Article, Conference Proceeding
Peer reviewed
Open access
We present a Lanczos algorithm utilizing multiple grids that reduces the memory requirements both on disk and in working memory by one order of magnitude for RBC/UKQCD’s 48I and 64I ensembles at the ...physical pion mass. The precision of the resulting eigenvectors is on par with exact deflation.
We present a method for calculating eigenvectors of the staggered Dirac operator based on the Golub-Kahan-Lanczos bidiagonalization algorithm. Instead of using orthogonalization during the ...bidiagonalization procedure to increase stability, we choose to stabilize the method by combining it with an outer iteration that refines the approximate eigenvectors obtained from the inner bidiagonalization procedure. We discuss the performance of the current implementation using QEX and compare with other methods.
In this paper we introduce a new type of preferential attachment network, the growth of which is based on the eigenvector centrality. In this network, the agents attach most probably to the nodes ...with larger eigenvector centrality which represents that the agent has stronger connections. A new network is presented, namely a dandelion network, which shares some properties of star-like structure and also a hierarchical network. We show that this network, having hub-and-spoke topology is not generally scale free, and shows essential differences with respect to the Barabási–Albert preferential attachment model. Most importantly, there is a super hub agent in the system (identified by a pronounced peak in the spectrum), and the other agents are classified in terms of the distance to this super-hub. We explore a plenty of statistical centralities like the nodes degree, the betweenness and the eigenvector centrality, along with various measures of structure like the community and hierarchical structures, and the clustering coefficient. Global measures like the shortest path statistics and the self-similarity are also examined.
We study the nonleptonic two-body weak decays of Λb by modifying the MIT bag model without introducing new parameters to construct the momentum eigenstates of the baryons. We find that the branching ...ratios of Λ0b → Λ+cπ−, Λ+cK−, pπ−, and pK− are (4.5 ± 0.2) × 10−3, (3.4 ± 0.1) × 10−4, (5.0 ± 0.5) × 10−6, and (6.0 ± 0.7) × 10−6, which are all consistent with the current experimental data, respectively. We also explore P and CP asymmetries for the decays of Λ0b → p (π−, K−). In particular, we obtain that the direct C P -violating rate asymmetries in Λ0b → pπ− and Λ0b → pK− are around −4.4% and 6.7%, in comparison with (−2.5 ± 2.9) % and (−2.5 ± 2.2)% from the Particle Data Group in 2020, respectively.
We investigate Bsπ+ scattering in s-wave using lattice QCD in order to search for an exotic resonance X(5568) with flavor b¯sd¯u; such a state was recently reported by D0 but was not seen by LHCb. If ...X(5568) with JP=0+ exists, it can strongly decay only to Bsπ+ and lies significantly below all other thresholds, which makes a lattice search for X(5568) cleaner and simpler than for other exotic candidates. Both an elastic resonance in Bsπ+ as well as a deeply bound B+K¯0 would lead to distinct signatures in the energies of lattice eigenstates, which are not seen in our simulation. We therefore do not find a candidate for X(5568) with JP=0+ in agreement with the recent LHCb result. The extracted Bsπ+ scattering length is compatible with zero within the error.
The effective Δmee2 in matter Denton, Peter B; Parke, Stephen J
Physical review. D,
11/2018, Volume:
98, Issue:
9
Journal Article
Peer reviewed
Open access
In this paper, we generalize the concept of an effective Δmee2 for νe/ν¯e disappearance experiments, which has been extensively used by the short baseline reactor experiments, to include the effects ...of propagation through matter for longer baseline νe/ν¯e disappearance experiments. This generalization is a trivial, linear combination of the neutrino mass squared eigenvalues in matter and thus is not a simple extension of the usually vacuum expression, although, as it must, it reduces to the correct expression in the vacuum limit. We also demonstrated that the effective Δmee2 in matter is very useful conceptually and numerically for understanding the form of the neutrino mass squared eigenstates in matter and hence for calculating the matter oscillation probabilities. Finally, we analytically estimate the precision of this two-flavor approach and numerically verify that it is precise at the subpercent level.
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