161,570 research outputs found

    Notes on nonabelian (0,2) theories and dualities

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    In this paper we explore basic aspects of nonabelian (0,2) GLSM's in two dimensions for unitary gauge groups, an arena that until recently has largely been unexplored. We begin by discussing general aspects of (0,2) theories, including checks of dynamical supersymmetry breaking, spectators and weak coupling limits, and also build some toy models of (0,2) theories for bundles on Grassmannians, which gives us an opportunity to relate physical anomalies and trace conditions to mathematical properties. We apply these ideas to study (0,2) theories on Pfaffians, applying recent perturbative constructions of Pfaffians of Jockers et al. We discuss how existing dualities in (2,2) nonabelian gauge theories have a simple mathematical understanding, and make predictions for additional dualities in (2,2) and (0,2) gauge theories. Finally, we outline how duality works in open strings in unitary gauge theories, and also describe why, in general terms, we expect analogous dualities in (0,2) theories to be comparatively rare.Comment: 93 pages, LaTeX; v2: typos fixe

    Integrable representations of the quantum affine special linear superalgebra

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    The simple integrable modules with finite dimensional weight spaces are classified for the quantum affine special linear superalgebra \U_q(\hat{\mathfrak{sl}}(M|N)) at generic qq. Any such module is shown to be a highest weight or lowest weight module with respect to one of the two natural triangular decompositions of the quantum affine superalgebra depending on whether the level of the module is zero or not. Furthermore, integrable \U_q(\hat{\mathfrak{sl}}(M|N))-modules at nonzero levels exist only if MM or NN is 11.Comment: 31 page

    Prediction of narrow NN^{*} and Λ\Lambda^* resonances with hidden charm above 4 GeV

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    The interaction between various charmed mesons and charmed baryons are studied within the framework of the coupled channel unitary approach with the local hidden gauge formalism. Several meson-baryon dynamically generated narrow NN^* and Λ\Lambda^* resonances with hidden charm are predicted with mass above 4 GeV and width smaller than 100 MeV. The predicted new resonances definitely cannot be accommodated by quark models with three constituent quarks and can be looked for at the forthcoming PANDA/FAIR experiments.Comment: 4 pages, 3 figure

    Cosmic rays in early star-forming galaxies and their effects on the interstellar medium

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    Galaxies at high redshifts with strong star formation are sources of high-energy cosmic rays. These cosmic rays interact with the baryon and radiation fields of the galactic environment via photo-pair, photo-pion and proton-proton processes to produce charged and neutral pions, neutrons and protons. The cosmic rays thereby deposit energy into the interstellar medium (ISM) as they propagate. We show how energy transport and deposition by ultra high-energy cosmic rays is regulated by the evolution of the galaxy, in particular by the development of the galactic magnetic field. We show how the particle-driven energy deposition can influence the thermal evolution of the host and its surroundings. Using a parametric protogalaxy model, we calculate the heating effect on the ISM as the cosmic rays are increasingly confined by the magnetic evolution of the galaxy.Comment: 8 pages, 2 figures; Proceedings of the 35th International Cosmic Ray Conference (ICRC2017), 10-20 July 2017, Bexco, Busan, Korea - PoS(ICRC2017)28

    Local dynamics in high-order harmonic generation using Bohmian trajectories

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    We investigate high-order harmonic generation from a Bohmian-mechanical perspective, and find that the innermost part of the core, represented by a single Bohmian trajectory, leads to the main contributions to the high-harmonic spectra. Using time-frequency analysis, we associate this central Bohmian trajectory to an ensemble of unbound classical trajectories leaving and returning to the core, in agreement with the three step model. In the Bohmian scenario, this physical picture builds up non-locally near the core via the quantum mechanical phase of the wavefunction. This implies that the flow of the wavefunction far from the core alters the central Bohmian trajectory. We also show how this phase degrades in time for the peripheral Bohmian trajectories as they leave the core region.Comment: 7 pages, 3 figures; the manuscript has been considerably extended and modified with regard to the previous version

    Direct diffusion through interpenetrating networks: Oxygen in titanium

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    How impurity atoms move through a crystal is a fundamental and recurrent question in materials. The previous understanding of oxygen diffusion in titanium relied on interstitial lattice sites that were recently found to be unstable, making the diffusion pathways for oxygen unknown. Using first-principles quantum-mechanical methods, we find three oxygen interstitial sites in titanium, and quantify the multiple interpenetrating networks for oxygen diffusion. Surprisingly, no single transition dominates, but all contribute to diffusion.Comment: 10 pages, 3 figures; additional supporting materia

    Atemporal diagrams for quantum circuits

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    A system of diagrams is introduced that allows the representation of various elements of a quantum circuit, including measurements, in a form which makes no reference to time (hence ``atemporal''). It can be used to relate quantum dynamical properties to those of entangled states (map-state duality), and suggests useful analogies, such as the inverse of an entangled ket. Diagrams clarify the role of channel kets, transition operators, dynamical operators (matrices), and Kraus rank for noisy quantum channels. Positive (semidefinite) operators are represented by diagrams with a symmetry that aids in understanding their connection with completely positive maps. The diagrams are used to analyze standard teleportation and dense coding, and for a careful study of unambiguous (conclusive) teleportation. A simple diagrammatic argument shows that a Kraus rank of 3 is impossible for a one-qubit channel modeled using a one-qubit environment in a mixed state.Comment: Minor changes in references. Latex 32 pages, 13 figures in text using PSTrick

    Competing orders and inter-layer tunnelling in cuprate superconductors: A finite temperature Landau theory

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    We propose a finite temperature Landau theory that describes competing orders and interlayer tunneling in cuprate superconductors as an important extension to a corresponding theory at zero temperature [Nature {\bf 428}, 53 (2004)], where the superconducting transition temperature TcT_c is defined in three possible ways as a function of the zero temperature order parameter. For given parameters, our theory determines TcT_c without any ambiguity. In mono- and double-layer systems we discuss the relation between zero temperature order parameter and the associated transition temperature in the presence of competing orders, and draw a connection to the puzzling experimental fact that the pseudo-gap temperature is much higher than the corresponding energy scale near optimum doping. Applying the theory to multi-layer systems, we calculate the layer-number dependence of TcT_c. In a reasonable parameter space the result turns out to be in agreement with experiments.Comment: 5 pages, 3 figure
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