20,268 research outputs found

    Dimensional Regularization and Dimensional Reduction in the Light Cone

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    We calculate all the 2 to 2 scattering process in Yang-Mills theory in the Light Cone gauge, with the dimensional regulator as the UV regulator. The IR is regulated with a cutoff in q+q^+. It supplements our earlier work, where a Lorentz non-covariant regulator was used and the final results bear some problems in gauge fixing. Supersymmetry relations among various amplitudes are checked using the light cone superfields.Comment: current version accepted by PR

    Subcritical Superstrings

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    We introduce the Liouville mode into the Green-Schwarz superstring. Like massive supersymmetry without central charges, there is no kappa symmetry. However, the second-class constraints (and corresponding Wess-Zumino term) remain, and can be solved by (twisted) chiral superspace in dimensions D=4 and 6. The matter conformal anomaly is c = 4-D < 1. It thus can be canceled for physical dimensions by the usual Liouville methods, unlike the bosonic string (for which the consistency condition is c = D <= 1).Comment: 9 pg., compressed postscript file (.ps.Z), other formats (.dvi, .ps, .ps.Z, 8-bit .tex) available at http://insti.physics.sunysb.edu/~siegel/preprints/ or at ftp://max.physics.sunysb.edu/preprints/siege

    The Isometries of Low-Energy Heterotic M-Theory

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    We study the effective D=4, N=1 supergravity description of five-dimensional heterotic M-theory in the presence of an M5 brane, and derive the Killing vectors and isometry group for the Kahler moduli-space metric. The group is found to be a non-semisimple maximal parabolic subgroup of Sp(4,R), containing a non-trivial SL(2,R) factor. The underlying moduli-space is then naturally realised as the group space Sp(4,R)/U(2), but equipped with a nonhomogeneous metric that is invariant only under that maximal parabolic group. This nonhomogeneous metric space can also be derived via field truncations and identifications performed on Sp(8,R)/U(4) with its standard homogeneous metric. In a companion paper we use these symmetries to derive new cosmological solutions from known ones.Comment: 11 pages, 1 table; two foonotes added, minor corrections to conten

    Effectively Closed Infinite-Genus Surfaces and the String Coupling

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    The class of effectively closed infinite-genus surfaces, defining the completion of the domain of string perturbation theory, can be included in the category OGO_G, which is characterized by the vanishing capacity of the ideal boundary. The cardinality of the maximal set of endpoints is shown to be 2^{\mit N}. The product of the coefficient of the genus-g superstring amplitude in four dimensions by 2g2^g in the gg\to \infty limit is an exponential function of the genus with a base comparable in magnitude to the unified gauge coupling. The value of the string coupling is consistent with the characteristics of configurations which provide a dominant contribution to a finite vacuum amplitude.Comment: TeX, 33 page

    Heat-transfer and pressure drop correlations for hydrogen and nitrogen flowing through tungsten wire mesh at temperatures to 5200 deg r

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    Heat transfer and friction pressure drop for forced convection of hydrogen and nitrogen through electrically heated tungsten wire mes

    A 4500 deg R /2500 deg K/ flowing-gas facility

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    High temperature flowing gas heater consisting of four stages for heating gase

    Behavioural clusters and predictors of performance during recovery from stroke

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    We examined the patterns and variability of recovery post-stroke in multiple behavioral domains. A large cohort of first time stroke patients with heterogeneous lesions was studied prospectively and longitudinally at 1-2 weeks, 3 months and one year post-injury with structural MRI to measure lesion anatomy and in-depth neuropsychological assessment. Impairment was described at all timepoints by a few clusters of correlated deficits. The time course and magnitude of recovery was similar across domains, with change scores largely proportional to the initial deficit and most recovery occurring within the first three months. Damage to specific white matter tracts produced poorer recovery over several domains: attention and superior longitudinal fasciculus II/III, language and posterior arcuate fasciculus, motor and corticospinal tract. Finally, after accounting for the severity of the initial deficit, language and visual memory recovery/outcome was worse with lower education, while the occurrence of multiple deficits negatively impacted attention recovery

    Green-Schwarz Formulation of Self-Dual Superstring

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    The self-dual superstring has been described previously in a Neveu-Schwarz-Ramond formulation with local N=2 or 4 world-sheet supersymmetry. We present a Green-Schwarz-type formulation, with manifest spacetime supersymmetry.Comment: 11 pg., (uuencoded dvi file) ITP-SB-92-5
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