Determination of the neutron electric form factor in quasielastic scattering of polarized electrons from polarized 3He

We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized 3He gas target. The asymmetry is measured at kinematics sensitive to the transverse-longitudinal response function RTL(Q2,ω). The value of the neutron electric form factor GEn(Q2=0.16 (GeV/c2))=+0.070±0.100±0.035 is extracted from the asymmetry using a Faddeev calculation of the 3He wave function

Angle-resolved photoemission in doped charge-transfer Mott insulators

A theory of angle-resolved photoemission (ARPES) in doped cuprates and other charge-transfer Mott insulators is developed taking into account the realistic (LDA+U) band structure, (bi)polaron formation due to the strong electron-phonon interaction, and a random field potential. In most of these materials the first band to be doped is the oxygen band inside the Mott-Hubbard gap. We derive the coherent part of the ARPES spectra with the oxygen hole spectral function calculated in the non-crossing (ladder) approximation and with the exact spectral function of a one-dimensional hole in a random potential. Some unusual features of ARPES including the polarisation dependence and spectral shape in YBa2Cu3O7 and YBa2Cu4O8 are described without any Fermi-surface, large or small. The theory is compatible with the doping dependence of kinetic and thermodynamic properties of cuprates as well as with the d-wave symmetry of the superconducting order parameter.Comment: 8 pages (RevTeX), 10 figures, submitted to Phys. Rev.

The Idea of Social Life

This paper reclaims the idea that human society is a form of life, an idea once vibrant in the work of Toennies, Durkheim, Simmel, Le Bon, Kroeber, Freud, Bion, and Follett but moribund today. Despite current disparagements, this idea remains the only and best answer to our primary experience of society as vital feeling. The main obstacle to conceiving society as a life is linguistic; the logical form of life is incommensurate with the logical form of language. However, it is possible to extend our conceptual reach by appealing to alternative symbolisms more congenial to living form such as, and especially, art.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68336/2/10.1177_004839319502500201.pd

The present and future of QCD

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades

DISORDERED SUPERSTRUCTURES

Les méthodes de fabrication de semiconducteurs, telles que l'épitaxie par jet moléculaire et la croissance de couches moléculaires par dépôt dans le vide, permettent d'obtenir des semiconducteurs lamellaires, avec un désordre partiellement ou complètement contrôlé. Nous allons discuter un certain nombre de cas pouvant être potentiellement étudiés. (1) Les surstructures à désordre aléatoire. Ce type de structures est obtenu, par exemple, par croissance de couches de GaAs/AlxGa1-xAs dont les épaisseurs, les compositions ou le dopage sont délibérément contrôlés par un nombre générateur aléatoire et présentent ainsi un désordre aléatoire reproductible. Les énergies et les éléments de matrice de l'effet tunnel entre les puits de potentiel sont fonction de l'épaisseur de ces couches. Ces éléments de matrice dépendent principalement de la composition des couches. Des microchamps électriques sont produits quand on altère le dopage. Une caractéristique intéressante des surstructures aléatoires est leur dimension spatiale finie, ce qui permet d'étudier 1'apparition de la localisation des électrons en fonction de la taille de 1'échantillon. La possibilité de faire croître des semiconducteurs décrits de façon réaliste par le modèle de désordre d'Anderson, (ou une variante de ce modèle) sera discutée. Des prédictions des effets du désordre sur la densité d'états électroniques seront données. (2) Désordre aléatoire microscopique. A une échelle microscopique (5Å), les états électroniques ne sont pas sensibles au désordre parce qu'ils sont "amalgamés", mais les états des phonons y sont sensibles dans virtuellement tous les semiconducteurs. Nous allons prédire les densités d'états des phonons de volume dans des alliages semiconducteurs stables et métastables. Et, si notre recherche progresse bien pendant le temps situé entre la soumission de ce résumé et la conférence, nous pourrons présenter des résultats sur des super-réseaux faits avec des alliages.Semiconductor fabrication schemes such as MBE and MOCVD offer the opportunity to grow layered semiconductors with disorder that is partially or fully controlled. We shall discuss a number of cases for potential study. (1) Random superstructures. For these structures, one grows layers of, say, GaAs/AlxGa1-xAs, whose thicknesses, compositions, or doping are deliberately controlled by a random number generator, and so are reproducibly random. Varying the thicknesses causes the energies and inter-well tunnelling matrix elements of quantum-well electronic states to vary ; varying the compositions changes primarily the inter-well matrix elements ; and altering the doping produces random electric microfields. An interesting feature of random superstructures is that they are finite in extent, and offer the possibility of studying the onset of electronic localization as a function of size. The possibility of growing semiconductors that are realistically described by Anderson's model of disorder (or variant's of Anderson's model) will be discussed. Predictions of the effects of the disorder on the electronic density of states will be given. (2) Microscopic randomness. On a microscopic (5Å) scale electronic states are insensitive to disorder because they are "amalgamated", but phonon states are disorder-sensitive for virtually all of the semiconductors. We shall present predictions of phonon spectral densities for bulk semiconducting alloys, both stable and metastable ; and, provided our research goes well during the period between submission of this abstract and the conference, we shall present results for alloy superlattices

Théorie des niveaux profonds de lacunes dans In1-yGayAs 1-xPx

The energies of A1- and T2-symmetric deep levels associated with isolated vacancies in In1-yGayAs 1-xPx are predicted.Les énergies des niveaux profonds de symétrie A1 et T2 relatifs à des lacunes isolées dans In1-yGayAS 1-xPx sont prévues

An annotated list of the birds of meandarra, queensland

From June 1977 to January 1982 the Meandarra Ornithological Field Study Unit kept systematic records of buds observed at its main study site centred on 'The Dell' and at a few selected localities near Meandarra, Queensland. A total of 172 species is included with 69 known to breed. The status, numbers and reproductive activities are sum- marized for the 160 species observed at 'The Dell'. A few records from the period 1969 to 1976 provide a historical perspective. Ranges of three pairs of species that replace each other on an east-west gradient overlapped at the study site. Twenty- three per cent of the total number of species were vagrants and thirty-one per cent were transients. Eleven per cent of the species in the list were added in the final three months of the study, following heavy rains. We speculate on the influence that topography, climate and more local conditions such as soil type, vegetation and rainfall mav have on the avifauna. As an illustration. we report changes in the populations of some species during a severe drought in 1979-1981