7,603 research outputs found

    Triple and quartic interactions of Higgs bosons in the two-Higgs-doublet model with CP violation

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    We consider the two-Higgs-doublet model with explicit CP-violation, where the effective Higgs potential is not CP-invariant at the tree-level. Three neutral Higgs bosons of the model are the mixtures of CP-even and CP-odd bosons which exist in the CP-conserving limit of the theory. The mass spectrum and tree-level couplings of the neutral Higgs bosons to gauge bosons and fermions are significantly dependent on the parameters of the Higgs boson mixing matrix. We calculate the Higgs-gauge boson, Higgs-fermion, triple and quartic Higgs self-interactions in the MSSM with explicit CP-violation in the Higgs sector and CP-violating Yukawa interactions of the third generation scalar quarks. In some regions of the MSSM parameter space substantial changes of the self-interaction vertices take place, leading to significant suppression or enhancement of the multiple Higgs boson production cross sections.Comment: 29 pages, 4 figures. Minor changes in section 3, misprints in (47) corrected. Version accepted by EPJ

    Engineering physics of superconducting hot-electron bolometer mixers

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    Superconducting hot-electron bolometers are presently the best performing mixing devices for the frequency range beyond 1.2 THz, where good quality superconductor-insulator-superconductor (SIS) devices do not exist. Their physical appearance is very simple: an antenna consisting of a normal metal, sometimes a normal metal-superconductor bilayer, connected to a thin film of a narrow, short superconductor with a high resistivity in the normal state. The device is brought into an optimal operating regime by applying a dc current and a certain amount of local- oscillator power. Despite this technological simplicity its operation has been found to be controlled by many different aspects of superconductivity, all occurring simultaneously. A core ingredient is the understanding that there are two sources of resistance in a superconductor: a charge conversion resistance occurring at an normal-metal-superconductor interface and a resistance due to time- dependent changes of the superconducting phase. The latter is responsible for the actual mixing process in a non-uniform superconducting environment set up by the bias-conditions and the geometry. The present understanding indicates that further improvement needs to be found in the use of other materials with a faster energy-relaxation rate. Meanwhile several empirical parameters have become physically meaningful indicators of the devices, which will facilitate the technological developments.Comment: This is an author-processed copy of an Invited contribution to the Special Issue of the IEEE Transactions on Terahertz Science and Technology dedicated to the 28th IEEE International Symposium on Space Terahertz Technology (ISSTT2017

    Quasi-two-dimensional complex plasma containing spherical particles and their binary agglomerates

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    A new type of quasi-two-dimensional complex plasma system was observed which consisted of monodisperse microspheres and their binary agglomerations (dimers). The particles and their dimers levitated in a plasma sheath at slightly different heights and formed two distinct sublayers. The sys- tem did not crystallize and may be characterized as disordered solid. The dimers were identified based on their characteristic appearance in defocused images, i.e., rotating interference fringe pat- terns. The in-plane and inter-plane particle separations exhibit nonmonotonic dependence on the discharge pressure which agrees well with theoretical predictions

    Classical and Quantum Nonultralocal Systems on the Lattice

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    We classify nonultralocal Poisson brackets for 1-dimensional lattice systems and describe the corresponding regularizations of the Poisson bracket relations for the monodromy matrix . A nonultralocal quantum algebras on the lattices for these systems are constructed.For some class of such algebras an ultralocalization procedure is proposed.The technique of the modified Bethe-Anzatz for these algebras is developed.This technique is applied to the nonlinear sigma model problem.Comment: 33 pp. Latex. The file is resubmitted since it was spoiled during transmissio

    Drinfeld-Sokolov reduction for difference operators and deformations of W-algebras. II. General Semisimple Case

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    The paper is the sequel to q-alg/9704011. We extend the Drinfeld-Sokolov reduction procedure to q-difference operators associated with arbitrary semisimple Lie algebras. This leads to a new elliptic deformation of the Lie bialgebra structure on the associated loop algebra. The related classical r-matrix is explicitly described in terms of the Coxeter transformation. We also present a cross-section theorem for q-gauge transformations which generalizes a theorem due to R.Steinberg.Comment: 19 pp., AMS-LaTeX. The paper replaces a temporarily withdrawn text; the first part (written by E. Frenkel, N. Reshetikhin, and M. A. Semenov-Tian-Shansky) is available as q-alg/970401

    Dual parametrization of GPDs versus the double distribution Ansatz

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    We establish a link between the dual parametrization of GPDs and a popular parametrization based on the double distribution Ansatz, which is in prevalent use in phenomenological applications. We compute several first forward-like functions that express the double distribution Ansatz for GPDs in the framework of the dual parametrization and show that these forward-like functions make the dominant contribution into the GPD quintessence function. We also argue that the forward-like functions Q2ν(x)Q_{2 \nu}(x) with ν≥1\nu \ge 1 contribute to the leading singular small-xBjx_{Bj} behavior of the imaginary part of DVCS amplitude. This makes the small-xBjx_{Bj} behavior of \im A^{DVCS} independent of the asymptotic behavior of PDFs. Assuming analyticity of Mellin moments of GPDs in the Mellin space we are able to fix the value of the DD-form factor in terms of the GPD quintessence function N(x,t)N(x,t) and the forward-like function Q0(x,t)Q_0(x,t).Comment: 18 pages, 5 figures. A version that appeared in Eur. Phys. J. A. Some of the statements were refined and misprints in the formulas were correcte

    Thermal budget of superconducting digital circuits at sub-kelvin temperatures

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    Superconducting single-flux-quantum (SFQ) circuits have so far been developed and optimized for operation at or above helium temperatures. The SFQ approach, however, should also provide potentially viable and scalable control and read-out circuits for Josephson-junction qubits and other applications with much lower, milli-kelvin, operating temperatures. This paper analyzes the overheating problem which becomes important in this new temperature range. We suggest a thermal model of the SFQ circuits at sub-kelvin temperatures and present experimental results on overheating of electrons and silicon substrate which support this model. The model establishes quantitative limitations on the dissipated power both for "local" electron overheating in resistors and "global" overheating due to ballistic phonon propagation along the substrate. Possible changes in the thermal design of SFQ circuits in view of the overheating problem are also discussed.Comment: 10 pages, 8 figures, submitted to J. Appl. Phy
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