1,698 research outputs found

    Planar Induced Subgraphs of Sparse Graphs

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    We show that every graph has an induced pseudoforest of at least nm/4.5n-m/4.5 vertices, an induced partial 2-tree of at least nm/5n-m/5 vertices, and an induced planar subgraph of at least nm/5.2174n-m/5.2174 vertices. These results are constructive, implying linear-time algorithms to find the respective induced subgraphs. We also show that the size of the largest KhK_h-minor-free graph in a given graph can sometimes be at most nm/6+o(m)n-m/6+o(m).Comment: Accepted by Graph Drawing 2014. To appear in Journal of Graph Algorithms and Application

    Anomalous Magnetic Moment of W-boson at high temperature

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    By the Schwinger proper-time method, the one-loop contribution to the anomalous magnetic moment of the W-boson is calculated at high temperature. It is shown that the value of AMM is positive and depends linearly upon temperature

    Search for τμ+γ\tau\to\mu+\gamma decay at Super cτc -\tau factory

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    A Monte Carlo study of possible background processes in a search for τμγ\tau \to \mu \gamma decay has been performed for conditions of the Super cτc-\tau factory (CTF) (at a center-of-mass energy 3.686 GeV, 3.77 GeV and 4.17 GeV). The background from τ+τ\tau^{+}\tau^{-} events has been analysed. Selection criteria for background suppression are suggested and necessary requirements on the detector characteristics have been found. The CTF can successfully compete with the Super B-factory in a search for τμγ\tau \to \mu \gamma decay.Comment: 3 pages, 1 figures; contribution to the Proceedings of the PHIPSI11 Workshop (Novosibirsk, Russia, 19-22 September 2011

    Strominger--Yau--Zaslow geometry, Affine Spheres and Painlev\'e III

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    We give a gauge invariant characterisation of the elliptic affine sphere equation and the closely related Tzitz\'eica equation as reductions of real forms of SL(3, \C) anti--self--dual Yang--Mills equations by two translations, or equivalently as a special case of the Hitchin equation. We use the Loftin--Yau--Zaslow construction to give an explicit expression for a six--real dimensional semi--flat Calabi--Yau metric in terms of a solution to the affine-sphere equation and show how a subclass of such metrics arises from 3rd Painlev\'e transcendents.Comment: 38 pages. Final version. To appear in Communications in Mathematical Physic

    Higgs potential bounds on extra quark-lepton generations

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    We consider the bounds for the values of higgs mass MHM_H and of the mass of the extra quarks and leptons MextraM_{extra} derived from the stability of vacuum and from the absence of Landau pole in Higgs potential. We find that in the case of the absence of new physics up to the GUT scale the bounds for the mass of the 4th generation are so restrictive that the negative result of CDF search for extra quarks closes the window for fourth generation. In the case of the absence of new physics up to 10510^5 GeV we get weaker but still nontrivial bounds on MHM_H and MextraM_{extra} as well.Comment: 7pp, LaTeX, uses epsf, 5 figures, PS file available at http://venus.itep.ru/preprints/1995/95058.ps.g

    Remarks on Form Factor Bounds

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    Improved model independent upper bounds on the weak transition form factors are derived using inclusive sum rules. Comparison of the new bounds with the old ones is made for the form factors h_{A_1} and h_V in B -> D* decays.Comment: 8 pages, 2 figures, title changed and typos corrected for journal publicatio

    Pyrolysis of rice husk and corn stalk in auger reactor:Part 1. Characterization of char and gas at various temperatures

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    In this study, rice husk and corn stalk have been pyrolyzed in an auger pyrolysis reactor at pyrolysis temperatures of 350, 400, 450, 500, 550, and 600 °C in order to investigate the effect of the pyrolysis temperature on the pyrolysis performance of the reactor and physicochemical properties of pyrolysis products (this paper focuses on char and gas). The results have shown that the pyrolysis temperature significantly affects the mass yields and properties of the pyrolysis products. The mass yields of pyrolysis liquid and char are comparable to those reported for the same feedstocks processed in fluidized bed reactors. With the increase of the pyrolysis temperature, the pyrolysis liquid yield shows a peak at 500 °C, the char yield decreases, and the gas yield increases for both feedstocks. The higher heating value (HHV) and volatile matter content of char increase as the pyrolysis temperature increases from 350 to 600 °C. The gases obtained from the pyrolysis of rice husk and corn stalk mainly contain CO2, CO, CH4, H2, and other light hydrocarbons; the molar fractions of combustible gases increase and therefore their HHVs subsequently increase with the increase of the pyrolysis temperature

    Signal Transmission Across Tile Assemblies: 3D Static Tiles Simulate Active Self-Assembly by 2D Signal-Passing Tiles

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    The 2-Handed Assembly Model (2HAM) is a tile-based self-assembly model in which, typically beginning from single tiles, arbitrarily large aggregations of static tiles combine in pairs to form structures. The Signal-passing Tile Assembly Model (STAM) is an extension of the 2HAM in which the tiles are dynamically changing components which are able to alter their binding domains as they bind together. For our first result, we demonstrate useful techniques and transformations for converting an arbitrarily complex STAM+^+ tile set into an STAM+^+ tile set where every tile has a constant, low amount of complexity, in terms of the number and types of ``signals'' they can send, with a trade off in scale factor. Using these simplifications, we prove that for each temperature τ>1\tau>1 there exists a 3D tile set in the 2HAM which is intrinsically universal for the class of all 2D STAM+^+ systems at temperature τ\tau (where the STAM+^+ does not make use of the STAM's power of glue deactivation and assembly breaking, as the tile components of the 2HAM are static and unable to change or break bonds). This means that there is a single tile set UU in the 3D 2HAM which can, for an arbitrarily complex STAM+^+ system SS, be configured with a single input configuration which causes UU to exactly simulate SS at a scale factor dependent upon SS. Furthermore, this simulation uses only two planes of the third dimension. This implies that there exists a 3D tile set at temperature 22 in the 2HAM which is intrinsically universal for the class of all 2D STAM+^+ systems at temperature 11. Moreover, we show that for each temperature τ>1\tau>1 there exists an STAM+^+ tile set which is intrinsically universal for the class of all 2D STAM+^+ systems at temperature τ\tau, including the case where τ=1\tau = 1.Comment: A condensed version of this paper will appear in a special issue of Natural Computing for papers from DNA 19. This full version contains proofs not seen in the published versio

    On the Origin of the Enhancementof CP-violating Charge Asymmetries in K3πK \rightarrow 3\pi Decays Predicted from Chiral Theory

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    We present an analysis of the enhancement of CP-violating charge asymmetries in K3πK \rightarrow 3\pi decays. Calculations of decay amplitudes are performed on the basis of bosonized strong and weak Lagrangians derived from QCD-motivated quark Lagrangians. We show that the interplay of fourth-order contributions of chiral Lagrangians for strong interactions and penguin operators in weak interactions significantly enhances the charge asymmetries.Comment: DESY 92-106, 15

    Charmless Exclusive Baryonic B Decays

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    We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than 10610^{-6}, except that \B(B^-\to p \bar\Delta^{--})\sim 1\times 10^{-6}. In general, BˉNΔˉ>BˉNNˉ\bar B\to N\bar\Delta>\bar B\to N\bar N due to the large coupling constant for ΣbBΔ\Sigma_b\to B\Delta. For three-body modes we focus on octet baryon final states. The leading three-dominated modes are Bˉ0pnˉπ(ρ),npˉπ+(ρ+)\bar B^0\to p\bar n\pi^-(\rho^-), n\bar p\pi^+(\rho^+) with a branching ratio of order 3×1063\times 10^{-6} for Bˉ0pnˉπ\bar B^0\to p\bar n\pi^- and 8×1068\times 10^{-6} for Bˉ0pnˉρ\bar B^0\to p\bar n\rho^-. The penguin-dominated decays with strangeness in the meson, e.g., BppˉK()B^-\to p\bar p K^{-(*)} and Bˉ0pnˉK(),nnˉKˉ0()\bar B^0\to p\bar n K^{-(*)}, n\bar n \bar K^{0(*)}, have appreciable rates and the NNˉN\bar N mass spectrum peaks at low mass. The penguin-dominated modes containing a strange baryon, e.g., Bˉ0Σ0pˉπ+,Σnˉπ+\bar B^0\to \Sigma^0\bar p\pi^+, \Sigma^-\bar n\pi^+, have branching ratios of order (14)×106(1\sim 4)\times 10^{-6}. In contrast, the decay rate of Bˉ0Λpˉπ+\bar B^0\to\Lambda\bar p\pi^+ is smaller. We explain why some of charmless three-body final states in which baryon-antibaryon pair production is accompanied by a meson have a larger rate than their two-body counterparts: either the pole diagrams for the former have an anti-triplet bottom baryon intermediate state, which has a large coupling to the BB meson and the nucleon, or they are dominated by the factorizable external WW-emission process.Comment: 46 pages and 3 figures, to appear in Phys. Rev. D. Major changes are: (i) Calculations of two-body baryonic B decays involving a Delta resonance are modified, and (ii) Penguin-dominated modes B-> Sigma+N(bar)+p are discusse
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