2,765 research outputs found

    Isotope shifts and hyperfine structure of the laser cooling Fe I 358-nm line

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    We report on the measurement of the isotope shifts of the 3d74sa5 ⁣F53d74pz5 ⁣G6o3d^74s \,\, a \, {}^5\!F_5 - 3d^74p \,\, z \, {}^5\!G^o_6 Fe~I line at 358~nm between all four stable isotopes 54{}^{54}Fe, 56{}^{56}Fe, 57{}^{57}Fe and 58{}^{58}Fe, as well as the hyperfine structure of that line for 57{}^{57}Fe, the only stable isotope having a nonzero nuclear spin. This line is of primary importance for laser cooling applications. In addition, an experimental value of the field and specific mass shift coefficients of the transition is reported as well as the hyperfine structure magnetic dipole coupling constant AA of the transition excited state in 57^{57}Fe, namely A(3d74pz5 ⁣G6o)=31.241(48)A(3d^74p \,\, z \, {}^5\!G^o_6)=31.241(48) MHz. The measurements were carried out by means of laser-induced fluorescence spectroscopy performed on an isotope-enriched iron atomic beam. All measured frequency shifts are reported with uncertainties below the third percent level.Comment: 5 pages, 5 figure

    Baryogenesis in the MSSM, nMSSM and NMSSM

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    We compare electroweak baryogenesis in the MSSM, nMSSM and NMSSM. We comment on the different sources of CP violation, the phase transition and constraints from EDM measurements.Comment: 6 pages, 4 figures. To appear in the proceedings of the 7th Conference on Strong and Electroweak Matter (SEWM06), Brookhaven National Laboratory, May 10-13, 200

    Overlap formulation of Majorana--Weyl fermions

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    An overlap method for regularizing Majorana--Weyl fermions interacting with gauge fields is presented. A mod(2) index is introduced in relation to the anomalous violation of a discrete global chiral symmetry. Most of the paper is restricted to 2 dimensions but generalizations to 2+8k dimensions should be straightforward.Comment: 8 pages, Plain Te

    Sériation des gravures piquetées du mont Bego (Alpes-Maritimes, France)

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    The site of Mount Bego is one of the most important rock art concentrations in Europe for recent Prehistory. After a study conducted for more than 45 years by Henry de Lumley, the majority of the 4,000 engraved rocks have been positioned and the near 36,000 engravings have been drawn. The engravings were firstly attributed to Chalcolithic and Early Bronze Age, on the basis of a comparison between the engraved weapons and real weapons that have been discovered in an archaeological context. During his PhD (2012), the author carried out the first systematic geostatistical analysis of the entire corpus, bringing out a series of effects (iconographic and geographic seriation, preferential location, etc.) in the engravings distribution. Thanks to the study of superimpositions, these quantitative results allow to consider a periodization of the main families of engravings. While weapon representations appear to be the most recent layer of engravings, reticulated figures and schematic horned figures seem to be the most ancient ones. Therefore, dating on the basis of weapon representations can no longer be considered valid for the entire corpus of engravings. Besides, Mount Bego site shows early occupations, as documented by archaeological artefacts (Cardial ceramics, Chassean flints, Recent Bell Beaker ceramics, etc.) and indices of human activities (certain since ca. 2400-1800 BC). This article presents the geostatistical predicates, methods (unimodality of realization periods of engraved themes, correlations, seriation, toposeriation, etc.) and principal results on which a first periodization frame has been built

    Isotope shifts and hyperfine structure of the Fe I 372 nm resonance line

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    We report measurements of the isotope shifts of the 3d64s2a5D43d64s4pz5F5o3d^64s^2 a ^5D_4 - 3d^64s4p z ^5F_5^o Fe I resonance line at 372 nm between all four stable isotopes 54^{54}Fe, 56^{56}Fe, 57^{57}Fe, and 58^{58}Fe, as well as the complete hyperfine structure of that line for 57^{57}Fe, the only stable isotope having a non-zero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant AA of the excited state of the transition in 57^{57}Fe: A(3d64s4pz5F5o)=81.69(86)A(3d^64s4p z ^5F_5^o) = 81.69(86) MHz. The measurements were done by means of Doppler-free laser saturated-absorption spectroscopy in a Fe-Ar hollow cathode using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent level.Comment: 5 pages, 5 figure

    The calculus of constructions

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    Generic Fibrational Induction

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    This paper provides an induction rule that can be used to prove properties of data structures whose types are inductive, i.e., are carriers of initial algebras of functors. Our results are semantic in nature and are inspired by Hermida and Jacobs' elegant algebraic formulation of induction for polynomial data types. Our contribution is to derive, under slightly different assumptions, a sound induction rule that is generic over all inductive types, polynomial or not. Our induction rule is generic over the kinds of properties to be proved as well: like Hermida and Jacobs, we work in a general fibrational setting and so can accommodate very general notions of properties on inductive types rather than just those of a particular syntactic form. We establish the soundness of our generic induction rule by reducing induction to iteration. We then show how our generic induction rule can be instantiated to give induction rules for the data types of rose trees, finite hereditary sets, and hyperfunctions. The first of these lies outside the scope of Hermida and Jacobs' work because it is not polynomial, and as far as we are aware, no induction rules have been known to exist for the second and third in a general fibrational framework. Our instantiation for hyperfunctions underscores the value of working in the general fibrational setting since this data type cannot be interpreted as a set.Comment: For Special Issue from CSL 201
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