| 1. |
- Schael, S, et al.
(author)
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Precision electroweak measurements on the Z resonance
- 2006
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In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Research review (peer-reviewed)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Galakhov, V. R., et al.
(author)
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Electronic structure and x-ray spectra of defective oxides LixCoO2
- 2006
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 74:4, s. 045120-
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Journal article (peer-reviewed)abstract
- X-ray absorption, resonant x-ray emission, and x-ray photoelectron spectra of the valence band and core levels have been measured for LixCoO2 (0.6 <= x <= 1.0). Resonant O K alpha x-ray emission spectra of LiCoO2 showed localized excitonic states due to a dd transition between unoccupied and occupied Co 3d states. On the basis of measurements of Co 3s x-ray photoelectron and Co 2p and O 1s x-ray absorption spectra it was established that in defective cobaltites the electronic holes are localized mainly in O 2p states. Evidence of phase separation in LixCoO2 has been found.
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| 3. |
- Boukhvalov, D. W., et al.
(author)
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Electronic structure of a Mn-12 molecular magnet : Theory and experiment
- 2007
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:1, s. 014419-
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Journal article (peer-reviewed)abstract
- We used site-selective and element-specific resonant inelastic x-ray scattering (RIXS) to study the electronic structure and the electron interaction effects in the molecular magnet [Mn12O12(CH3COO)(16)(H2O)(4)]center dot 2CH(3)COOH center dot 4H(2)O, and compared the experimental data with the results of local spin density approximation +U electron structure calculations which include the on-site Coulomb interactions. We found a good agreement between theory and experiment for the Coulomb repulsion parameter U = 4 eV. In particular, the p-d band separation of 1.8 eV has been found from the RIXS spectra, which is in accordance with the calculations. Similarly, the positions of the peaks in the XPS spectra agree with the calculated densities of p and d states. Using the results of the electronic structure calculations, we determined the intramolecular exchange parameters, and used them for diagonalization of the Mn-12 spin Hamiltonian. The calculated exchanges gave the correct ground state with the total spin S = 10.
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| 4. |
- Brinck, Ingar, et al.
(author)
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From similarity to uniqueness: Method and theory in comparative psychology
- 2008
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In: Learning from Animals? Examining the Nature of Human Uniqueness. - 9781841697079
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Book chapter (peer-reviewed)abstract
- Comparative psychology is a strongly interdisciplinary field that shares many of its experimental methods and observational techniques with ethology and developmental psychology. The great variety of theories that comparative psychology evokes to explain behavior generates a wide array of exciting and potentially fruitful accounts, but is also problematic. It increases the risk of error in the forms of inconsistent background assumptions, conceptual misunderstandings, unfalsifiable hypotheses and incoherent explanations, which in spite of perhaps being minor by themselves will impede scientific progress in the long run. Moreover, similarly to psychology at large, comparative psychology tends to emphasize empirical investigations to the disadvantage of the analysis and development of theories and concepts. Consequently, disagreements that have their roots elsewhere than in methodology and experimental design do not receive sufficient attention. Furthermore, while evidence about biological evolution (i.e., the behavior and cognition of ancient animals) is notoriously hard to find, the methodology for comparing the capacities of different species is under continuous development. This forces comparative psychology to rely on the adequacy of the theoretical and conceptual framework to a greater extent than normally in the empirical sciences. In view of investigating the background of the problems that contemporary comparative psychology is facing, the present chapter examines central parts of the methodology and explanatory framework of comparative psychology as well as its global objective.
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| 5. |
- Enders, J, et al.
(author)
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Electric dipole strength below the giant dipole resonance
- 2005
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In: Acta Physica Polonica. Series B: Elementary Particle Physics, Nuclear Physics, Statistical Physics, Theory of Relativity, Field Theory. - 0587-4254. ; 36:4, s. 1077-1087
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Journal article (peer-reviewed)abstract
- Recent experimental findings and theoretical approaches to the electric dipole (El) strength distribution below the particle emission threshold at shell closures are revisited. Results from photon scattering experiments are discussed and compared to predictions within the quasiparticle-phonon nuclear model. An analysis of the fine structure of the El strength is presented. Recent studies of the E1 response of light exotic nuclei are also discussed.
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| 6. |
- Göök, A., et al.
(author)
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Photo-fission at the S-DALINAC
- 2009
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In: 4th international workshop on nuclear fission and fission-product spectroscopy. - : American Institute of Physics (AIP). - 9780735407145 ; , s. 351-354
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Conference paper (other academic/artistic)abstract
- Experiments on photo-induced fission of 238U and 234U using bremsstrahlung with endpoint energies between 6 MeV and 9 MeV have been carried out at the superconducting Darmstadt electron linear accelerator S-DALINAC. A twin Frisch grid ionization chamber has been used to determine energy and mass distributions via the 2E-technique. The fission fragment emission angle, which is used to correct for energy loss in the target and backing material for a correct determination of fragment energy and mass, is deduced from the time difference between cathode and anode signals. The research program including the foreseen search for parity violation in photo-induced fission and first experimental results will be presented. © 2009 American Institute of Physics.
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| 7. |
- Kantor, I, et al.
(author)
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Short-range order and Fe clustering in Mg1-xFexO under high pressure
- 2009
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 80:1, s. 014204-
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Journal article (peer-reviewed)abstract
- By combining high-pressure and high-temperature Moumlssbauer spectroscopic studies of (Mg,Fe)O with results of ab initio simulations, several important properties of this material were established. Under high pressure (Mg,Fe)O shows changes in the short-range order with the tendency to form iron clusters. These changes were found to be irreversible, implying sluggish kinetics of these processes at ambient conditions. The pressure-induced spin crossover is interpreted here as a gradual noncooperative transition. The onset and width of spin crossover depends, therefore, not only on pressure, temperature, and composition, but also on short-range order in the FeO-MgO solid solution.
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