Analyzing the Effects of Neutron Polarizabilities in Elastic Compton Scattering off 3{}^3He

Motivated by the fact that a polarized ${}^3$He nucleus behaves as an `effective' neutron target, we examine manifestations of neutron electromagnetic polarizabilities in elastic Compton scattering from the Helium-3 nucleus. We calculate both unpolarized and double-polarization observables using chiral perturbation theory to next-to-leading order (${\mathcal O}(e^2 Q)$) at energies, $\omega \leq m_{\pi}$, where $m_{\pi}$ is the pion mass. Our results show that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities. [Note added in 2018] The qualitative conclusions and analytic formulae presented in this paper are correct, but several of the numerical results are wrong: see the erratum posted as arXiv:1804.01206 for further details. A full suite of corrected numerical results for cross sections and asymmetries can be found in Margaryan et al., arXiv:1804.00956. They can also be obtained as an interactive Mathematica notebook by emailing [email protected]: 40 pages, 16 figure

East Prussia and its posthumous life: on the tenacious vitality of a historical phenomenon

The paper is a keynote address to the conference 'Contacts and Cultural Transfer in the Historical Region of East Prussia (1700-2000)' that took place in Nida in September 2013. It considers what the East Prussia region means, and what it is associated with today, after it stopped existing 70 years ago. The question is asked what the current situation of East Prussian historiography is, and potential directions for the development of new relevant research are outlined. The author argues that in the process of the cognition of East Prussia, a shift was made from the conservative system of meanings, developed mainly by the former local elites in Germany after the Second World War, to the cognition of regional diversity, which existed before the era of nationalism, and to coping with national narratives about East Prussia. Simultaneously, in the former territory of East Prussia, which currently belongs to Poland, Russia and Lithuania, individual elements of the past of the region continue to occupy an increasingly important role in layers of the local identity, and form opportunities for local cultures of remembrance

Von der frontier zum Binnenraum: Visionen und Repräsentationen Sibiriens als innerrussländischer Grenzraum

Häfner L. Von der frontier zum Binnenraum: Visionen und Repräsentationen Sibiriens als innerrussländischer Grenzraum. In: Duhamelle C, Kossert A, Struck B, eds. Grenzregionen. ein europäischer Vergleich vom 18. bis zum 20. Jahrhundert. Frankfurt/M. : Campus; 2007: 25-50

Quasi-free pi(0) photoproduction from the bound nucleon

Differential cross-sections for quasi-free pi(0) photoproduction from the proton and neutron bound in the deuteron have been measured for Egamma=200-400 MeV at theta(gamma)(lab)=136.2degrees using the Glasgow photon tagger at MAMI, the Mainz 48 cm empty set 64 cm NaI(Tl) photon detector and the Gottingen SENECA recoil detector. For the proton measurements made with both liquid-deuterium and liquid-hydrogen targets allow direct comparison of "free" pi(0) photoproduction cross-sections as extracted from the bound-proton data with experimental free cross-sections which are found to be in reasonable agreement below 320 MeV. At higher energies the "free" cross-sections extracted from quasi-free data are significantly smaller than the experimental free cross-sections and theoretical predictions based on multipole analysis. For the first time, "free" neutron cross-section have been extracted in the Delta-region. They are also in agreement with the predictions from multipole analysis up to 320 MeV and significantly smaller at higher photon energies

Helicity dependence of the gamma p → N pi channels and multipole analysis in the Delta region

A high-quality double-polarization data set for the helicity dependence of the total and differential cross-sections for both gammap --> Npi channels in the Delta region has been obtained in the framework of the GDH experiment. The experiment, performed at the Mainz microtron MAMI, used a 4pi detection system, a circularly polarized photon beam, and a longitudinally polarized frozen-spin target. These data are included in the database to perform a multipole analysis to determine the properties of the Delta(1232)-resonance. For the resonant Delta(1232) multipoles we find a very good agreement with previous analyses, while the nonresonant ones show significant deviations

First measurement of the Gerasimov-Drell-Hearn integral for H-1 from 200 to 800 MeV

A direct measurement of the helicity dependence of the total photoabsorption cross section an the proton was carried out at MAMI (Mainz) in the energy range 200 detection system, a circularly polarized. tagged photon beam, and a frozen spin target. The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward spin polarizability gamma (0) determined from the data are 226 +/- 5(stat) +/- 12(syst) mub and -187 +/- 8(stat) +/- 10(syst) x 10(-6) fm(4), respectively, for 200 < 800 MeV