1,620 research outputs found

    Relaxing Lorentz invariance in general perturbative anomalies

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    We analyze the role of Lorentz symmetry in the perturbative non-gravitational anomalies for a single family of fermions. The theory is assumed to be translational invariant, power-counting renormalizable and based on a local action, but is allowed to have general Lorentz violating operators. We study the conservation of global and gauge currents associate with general internal symmetry groups and find, by using a perturbative approach, that Lorentz symmetry does not participate in the clash of symmetries that leads to the anomalies. We first analyze the triangle graphs and prove that there are regulators for which the anomalous part of the Ward identities exactly reproduces the Lorentz invariant case. Then we show, by means of a regulator independent argument, that the anomaly cancellation conditions derived in Lorentz invariant theories remain necessary ingredients for anomaly freedom.Comment: 18 pages, 1 figure. Few comments added. Article published in Physical Review

    Hot Rocks! Near-Infrared Reflectances (and Emissivities) or Rocks at Venus Surface Temperatures

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    Venus surface can be viewed in emission through a few near-infrared (NIR) spectral windows (1 m) in its relatively opaque atmosphere [1]. Venus surface shows NIR emissivities that correlate with surface geology [2-4], and these emissivity variations are interpreted as differences in surface rock type (mafic vs. silicic) and/or extent of weathering (Fe2+ silicates vs. Fe3+-oxide-coated). To understand and quantify the observed variations in NIR emissivity, high-temperature (T) emissivity can be measured directly [5,6]. For example, emissivities of basalts in the wavelength range 0.85 1.2 m are ~0.95 [5-8]. This can be tested by measureing reflectance, because Kirchoffs Law holds that emissivity (e) = 1 reflectance (r). The r of basalt in the NIR is ~0.05 [o] consistent with a NIR e of ~0.95 [5-8]. High-T NIR es of silicic igneous rocks (granitic, rhyolite) have been reported to be 0.8-0.9 [5,6], which is inconsistent with r values of 0.3-0.8 of such rocks at 25C [9,10]. However, these measurements have been updated [7,8] and are consistent with the results here (see below and Fig. 3)

    The Martian sources of the SNC meteorites (two, not one), and what can and can't be learned from the SNC meteorites

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    The SNC meteorites, which almost certainly originate in the Martian crust, have been inferred to come from a single impact crater site, but no known crater fits all criteria. Formation at two separate sites (S from one, NC from the other) is more consistent with the sum of petrologic, geochronologic, and cosmochronologic data. If the source craters for the SNC meteorites can be located, Mars science will advance considerably. However, many significant questions cannot be answered by the SNC meteorites. These questions await a returned sample

    Workshop on Evolution of Martian Volatiles

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    This volume contains papers that were presented on February 12-14, 1996 at the Evolution for Martian Volatiles Workshop. Topics in this volume include: returned Martian samples; acidic volatiles and the Mars soil; solar EUV Radiation; the ancient Mars Thermosphere; primitive methane atmospheres on Earth and Mars; the evolution of Martian water; the role of SO2 for the climate history of Mars; impact crater morphology; the formation of the Martian drainage system; atmospheric dust-water ice Interactions; volatiles and volcanos; accretion of interplanetary dust particles; Mars' ionosphere; simulations with the NASA Ames Mars General Circulation Model; modeling the Martian water cycle; the evolution of Martian atmosphere; isotopic composition; solar occultation; magnetic fields; photochemical weathering; NASA's Mars Surveyor Program; iron formations; measurements of Martian atmospheric water vapor; and the thermal evolution Models of Mars

    Distribution amplitudes and decay constants for (π,K,ρ,K)(\pi,K,\rho,K^*) mesons in light-front quark model

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    We present a calculation of the quark distribution amplitudes(DAs), the Gegenbauer moments, and decay constants for π,ρ,K\pi,\rho,K and KK^* mesons using the light-front quark model. While the quark DA for π\pi is somewhat broader than the asymptotic one, that for ρ\rho meson is very close to the asymptotic one. The quark DAs for KK and KK^* show asymmetric form due to the flavor SU(3)-symmetry breaking effect. The decay constants for the transversely polarized ρ\rho and KK^* mesons(fρTf^T_\rho and fKTf^T_{K^*}) as well as the longitudinally polarized ones(fρf_\rho and fKf_{K^*}) are also obtained. Our averaged values for fVT/fVf^T_V/f_V, i.e. (fρT/fρ)av=0.78(f^T_\rho/f_\rho)_{\rm av}=0.78 and (fKT/fK)av=0.84(f^T_{K^*}/f_{K^*})_{\rm av}=0.84, are found to be consistent with other model predictions. Especially, our results for the decay constants are in a good agreement with the SU(6) symmetry relation, fρ(K)T=(fπ(K)+fρ(K))/2f^T_{\rho(K^*)}=(f_{\pi(K)}+f_{\rho(K^*)})/2.Comment: 12 pages, 6figure

    Lunar Meteorite NWA 11421: X-Ray Tomogrpahy & Preliminary Petrology

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    Lunar meteorite NWA 11421 is provisionally placed with the "NWA 8046 clan" of similar stones (the "Algerian Megafind") of which at least 33 kg has been recovered. NWA 11421 and pairs are feldspathic regolith breccias, with angular fragments of plagioclase-rich clasts in a dark glassy matrix. Most members of this clan contain < 5.5% FeO and < 0.3 ppm Th. To date, there have been no petrographic studies reported of these lunar meteorites. An 11.7 gm sample of NWA 11421 was purchased from Marcin Cimala, holder of the main mass - this sample is consistent in all respects with the formal meteorite description. This particular sample was selected because it appeared to contain a fragment of dunite

    Luttinger theorem for a spin-density-wave state

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    We obtained the analog of the Luttinger relation for a commensurate spin-density-wave state. We show that while the relation between the area of the occupied states and the density of particles gets modified in a simple and predictable way when the system becomes ordered, a perturbative consideration of the Luttinger theorem does not work due to the presence of an anomaly similar to the chiral anomaly in quantum electrodynamics.Comment: 4 pages, RevTeX, 1 figure embedded in the text, ps-file is also available at http://lifshitz.physics.wisc.edu/www/morr/morr_homepage.htm

    A Comprehensive Analysis on the Pion-Photon Transition Form Factor Beyond the Leading Fock State

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    We perform a comprehensive analysis of the pion-photon transition form factor Fπγ(Q2)F_{\pi \gamma}(Q^2) involving the transverse momentum corrections with the present CLEO experimental data, in which the contributions beyond the leading Fock state have been taken into consideration. As is well-known, the leading Fock-state contribution dominates of Fπγ(Q2)F_{\pi \gamma}(Q^2) at large momentum transfer (Q2Q^2) region. One should include the contributions beyond the leading Fock state in small Q2Q^2 region. In this paper, we construct a phenomenological expression to estimate the contributions beyond the leading Fock state based on its asymptotic behavior at Q20Q^2\to0. Our present theoretical results agree well with the experimental data in the whole Q2Q^2 region. Then, we extract some useful information of the pionic leading twist-2 distribution amplitude (DA) by comparing our results of Fπγ(Q2)F_{\pi \gamma}(Q^2) with the CLEO data. By taking best fit, we have the DA moments, a2(μ02)=0.0020.054+0.063a_2(\mu_0^2)=0.002^{+0.063}_{-0.054}, a4(μ02)=0.0220.012+0.026a_4(\mu_0^2)=-0.022_{-0.012}^{+0.026} and all of higher moments, which are closed to the asymptotic-like behavior of the pion wavefunction.Comment: 25 pages, 7 figures. Typo error correcte
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