308 research outputs found

    On the Simplicity of the Lie Algebras E7 and E8

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    Trace forms for structurable algebras

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    Note on Moufang-Noether currents

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    The derivative Noether currents generated by continuous Moufang tranformations are constructed and their equal-time commutators are found. The corresponding charge algebra turns out to be a birepresentation of the tangent Mal'ltsev algebra of an analytic Moufang loop.Comment: LaTeX2e, 6 pages, no figures, presented on "The XVth International Colloquium on Integrable Systems and Quantum Symmetries, Prague, 15-17 June, 2006

    Angular Momentum Mixing in Crystalline Color Superconductivity

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    In crystalline color superconductivity, quark pairs form at non-zero total momentum. This crystalline order potentially enlarges the domain of color superconductivity in cold dense quark matter. We present a perturbative calculation of the parameters governing the crystalline phase and show that this is indeed the case. Nevertheless, the enhancement is modest, and to lowest order is independent of the strength of the color interaction.Comment: 9 pages, 2 figures, Revte

    Influence of the U(1)_A Anomaly on the QCD Phase Transition

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    The SU(3)_{r} \times SU(3)_{\ell} linear sigma model is used to study the chiral symmetry restoring phase transition of QCD at nonzero temperature. The line of second order phase transitions separating the first order and smooth crossover regions is located in the plane of the strange and nonstrange quark masses. It is found that if the U(1)_{A} symmetry is explicitly broken by the U(1)_{A} anomaly then there is a smooth crossover to the chirally symmetric phase for physical values of the quark masses. If the U(1)_{A} anomaly is absent, then there is a phase transition provided that the \sigma meson mass is at least 600 MeV. In both cases, the region of first order phase transitions in the quark mass plane is enlarged as the mass of the \sigma meson is increased.Comment: 5 pages, 3 figures, Revtex, discussion extended and references added. To appear in PR

    Social Media and its Impact on Therapeutic Relationships

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    In the current age of social media, the boundaries between the online and the offline, the personal and the professional, have become blurred and ambiguous. This poses significant challenges to the practice of psychoanalysis, which for a long time has been thought of as a technology‐free and private space. This paper compares how social media impacts therapeutic relationships in the broader field of psychotherapy and in psychoanalytic psychotherapy in particular. Direct breaches in therapist privacy were found to be more frequent with non‐psychoanalytic psychotherapists due to therapists’ higher online presence. Psychoanalytic psychotherapists, on the other hand, generally have a lesser online presence because of different views on therapeutic anonymity from other clinical orientations. The author suggests that this leads to different forms of virtual impingements: due to the absence of psychoanalytic therapists’ online presence, patients seek to re‐create therapists (and, by extension, therapeutic situations) on a virtual level rather than discover something that was already ‘put out there’ by therapists. Virtual manifestations of anonymity, splitting, and solipsistic introjection processes are discussed with reference to John Suler's concept of the online disinhibition effect. Further recommendations for research on social media impact are discussed

    Large N_c, chiral approach to M_eta' at finite temperature

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    We study the temperature dependence of the eta and eta' meson masses within the framework of U(3)_L x U(3)_R chiral perturbation theory, up to next-to-leading order in a simultaneous expansion in momenta, quark masses and number of colours. We find that both masses decrease at low temperatures, but only very slightly. We analyze higher order corrections and argue that large N_c suggests a discontinuous drop of M_eta' at the critical temperature of deconfinement T_c, consistent with a first order transition to a phase with approximate U(1)_A symmetry.Comment: 21 pages, 6 figures. 2 footnotes added, 1 reference changed and 1 typo corrected. To be published in Phys. Rev.

    The Specific Heat of Normal, Degenerate Quark Matter: Non-Fermi Liquid Corrections

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    In normal degenerate quark matter, the exchange of dynamically screened transverse gluons introduces infrared divergences in the quark self-energies that lead to the breakdown of the Fermi liquid description. If the core of neutron stars are composed of quark matter with a normal component, cooling by direct quark Urca processes may be modified by non-Fermi liquid corrections. We find that while the quasiparticle density of states is finite and non-zero at the Fermi surface, its frequency derivative diverges and results in non-Fermi liquid corrections to the specific heat of the normal, degenerate component of quark matter. We study these non-perturbative non-Fermi liquid corrections to the specific heat and the temperature dependence of the chemical potential and show that these lead to a reduction of the specific heat.Comment: new discussion, updated references, accepted in PR

    Chirality Correlation within Dirac Eigenvectors from Domain Wall Fermions

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    In the dilute instanton gas model of the QCD vacuum, one expects a strong spatial correlation between chirality and the maxima of the Dirac eigenvectors with small eigenvalues. Following Horvath, {\it et al.} we examine this question using lattice gauge theory within the quenched approximation. We extend the work of those authors by using weaker coupling, ÎČ=6.0\beta=6.0, larger lattices, 16416^4, and an improved fermion formulation, domain wall fermions. In contrast with this earlier work, we find a striking correlation between the magnitude of the chirality density, âˆŁÏˆâ€ (x)Îł5ψ(x)∣|\psi^\dagger(x)\gamma^5\psi(x)|, and the normal density, ψ†(x)ψ(x)\psi^\dagger(x)\psi(x), for the low-lying Dirac eigenvectors.Comment: latex, 25 pages including 12 eps figure

    Geometric Configurations, Regular Subalgebras of E10 and M-Theory Cosmology

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    We re-examine previously found cosmological solutions to eleven-dimensional supergravity in the light of the E_{10}-approach to M-theory. We focus on the solutions with non zero electric field determined by geometric configurations (n_m, g_3), n\leq 10. We show that these solutions are associated with rank gg regular subalgebras of E_{10}, the Dynkin diagrams of which are the (line) incidence diagrams of the geometric configurations. Our analysis provides as a byproduct an interesting class of rank-10 Coxeter subgroups of the Weyl group of E_{10}.Comment: 48 pages, 27 figures, 5 tables, references added, typos correcte
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