5,170 research outputs found

    Cores with distinct parts and bigraded Fibonacci numbers

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    The notion of (a,b)(a,b)-cores is closely related to rational (a,b)(a,b) Dyck paths due to Anderson's bijection, and thus the number of (a,a+1)(a,a+1)-cores is given by the Catalan number CaC_a. Recent research shows that (a,a+1)(a,a+1) cores with distinct parts are enumerated by another important sequence- Fibonacci numbers FaF_a. In this paper, we consider the abacus description of (a,b)(a,b)-cores to introduce the natural grading and generalize this result to (a,as+1)(a,as+1)-cores. We also use the bijection with Dyck paths to count the number of (2k−1,2k+1)(2k-1,2k+1)-cores with distinct parts. We give a second grading to Fibonacci numbers, induced by bigraded Catalan sequence Ca,b(q,t)C_{a,b} (q,t)

    W/Z + jets and W/Z + heavy flavor production at the LHC

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    The ATLAS and CMS experiments at the LHC conduct an extensive program to study production of events with a W or Z boson and particle jets. Dedicated studies focus on final states with the jets containing decays of heavy-flavor hadrons (b-tagged jets). The results are obtained using data from proton-proton collisions at sqrt{s}=7 TeV from the LHC at CERN. The set of measurements constitute a stringent test of the perturbative QCD calculations.Comment: 4 pages, proceedings of the 47th Rencontres de Moriond on QCD and High Energy Interactions, La Thuile, Italy, 10-17 Mar 201

    Long-range Energy Transfer and Ionization in Extended Quantum Systems Driven by Ultrashort Spatially Shaped Laser Pulses

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    The processes of ionization and energy transfer in a quantum system composed of two distant H atoms with an initial internuclear separation of 100 atomic units (5.29 nm) have been studied by the numerical solution of the time-dependent Schr\"odinger equation beyond the Born-Oppenheimer approximation. Thereby it has been assumed that only one of the two H atoms was excited by temporally and spatially shaped laser pulses at various laser carrier frequencies. The quantum dynamics of the extended H-H system, which was taken to be initially either in an unentangled or an entangled ground state, has been explored within a linear three-dimensional model, including two z coordinates of the electrons and the internuclear distance R. An efficient energy transfer from the laser-excited H atom (atom A) to the other H atom (atom B) and the ionization of the latter have been found. It has been shown that the physical mechanisms of the energy transfer as well as of the ionization of atom B are the Coulomb attraction of the laser driven electron of atom A by the proton of atom B and a short-range Coulomb repulsion of the two electrons when their wave functions strongly overlap in the domain of atom B.Comment: 11 pages, 7 figure

    Fundamental characteristics of transverse deflecting field

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    The Panofsky-Wenzel theorem connects the transverse deflecting force in an rf structure with the existence of a longitudinal electric field component. In this paper it is shown that a transverse deflecting force is always accompanied by an additional longitudinal magnetic field component which leads to an emittance growth in the direction perpendicular to the transverse force. Transverse deflecting waves can thus not be described by pure TM or TE modes, but require a linear combination of basis modes for their representation. The mode description is preferably performed in the HM--HE basis to avoid converge problems, which are fundamental for the TM--TE basis.Comment: The sign in Eq.8 is corrected in May 201

    Crystal analysis of type CC Stanley symmetric functions

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    Combining results of T.K. Lam and J. Stembridge, the type CC Stanley symmetric function FwC(x)F_w^C(\mathbf{x}), indexed by an element ww in the type CC Coxeter group, has a nonnegative integer expansion in terms of Schur functions. We provide a crystal theoretic explanation of this fact and give an explicit combinatorial description of the coefficients in the Schur expansion in terms of highest weight crystal elements.Comment: 39 page

    Estimating Graphlet Statistics via Lifting

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    Exploratory analysis over network data is often limited by the ability to efficiently calculate graph statistics, which can provide a model-free understanding of the macroscopic properties of a network. We introduce a framework for estimating the graphlet count---the number of occurrences of a small subgraph motif (e.g. a wedge or a triangle) in the network. For massive graphs, where accessing the whole graph is not possible, the only viable algorithms are those that make a limited number of vertex neighborhood queries. We introduce a Monte Carlo sampling technique for graphlet counts, called {\em Lifting}, which can simultaneously sample all graphlets of size up to kk vertices for arbitrary kk. This is the first graphlet sampling method that can provably sample every graphlet with positive probability and can sample graphlets of arbitrary size kk. We outline variants of lifted graphlet counts, including the ordered, unordered, and shotgun estimators, random walk starts, and parallel vertex starts. We prove that our graphlet count updates are unbiased for the true graphlet count and have a controlled variance for all graphlets. We compare the experimental performance of lifted graphlet counts to the state-of-the art graphlet sampling procedures: Waddling and the pairwise subgraph random walk
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