The Illusion of Purity:Chantal Mouffe's Realist Critique of Cosmopolitanism

Over the last 20 years, cosmopolitan theories have been benefiting greatly from the dialogue between defenders and critics of world citizenship. Yet, the decidedly polemic aspect of this debate, while allowing for intellectual progress, is also responsible for overdrawn generalizations. Instead of entering into the debate directly, this article attempts to refute a specific anti-cosmopolitan claim raised by Chantal Mouffe. Her realist objection to cosmopolitanism, derived from the conceptual framework of agonistic pluralism, is mistaken at a crucial point: a firm dichotomy between politics and morality cannot provide an alternative to theories of world citizenship, because Mouffe’s embrace of multipolarity as a principle of global politics must equally appeal to a set of universal norms governing international relations. This article argues that even the realist model of multipolarity needs to conceive of a minimal morality to create the symbolic ground on which various power centres can be held accountable

Low density instability in a nuclear Fermi liquid drop

The instability of a Fermi-liquid drop with respect to bulk density distortions is considered. It is shown that the presence of the surface strongly reduces the growth rate of the bulk instability of the finite Fermi-liquid drop because of the anomalous dispersion term in the dispersion relation. The instability growth rate is reduced due to the Fermi surface distortions and the relaxation processes. The dependence of the bulk instability on the multipolarity of the particle density fluctuations is demonstrated for two nuclei $^{40}Ca$ and $^{208}Pb$.Comment: 12 pages, latex, 3 ps-figures, submitted to Phys. Rev.

Low-energy cross section of the 7Be(p,g)8B solar fusion reaction from Coulomb dissociation of 8B

Final results from an exclusive measurement of the Coulomb breakup of 8B into 7Be+p at 254 A MeV are reported. Energy-differential Coulomb-breakup cross sections are analyzed using a potential model of 8B and first-order perturbation theory. The deduced astrophysical S_17 factors are in good agreement with the most recent direct 7Be(p,gamma)8B measurements and follow closely the energy dependence predicted by the cluster-model description of 8B by Descouvemont. We extract a zero-energy S_17 factor of 20.6 +- 0.8 (stat) +- 1.2 (syst) eV b.Comment: 14 pages including 16 figures, LaTeX, accepted for publication in Physical Review C. Minor changes in text and layou

The internal Compton effect

Internal Compton effect, and use of superconducting magnet spectrometer to determine multipolarity assignment

The Photodissociation of 8B^8B and the Solar Neutrino Problem

The extraction of the photodissociation cross sections of $^8B$ from Coulomb dissociation experiments is investigated. A careful study is done on the contributions of the E1, E2 and M1 multipolarities to the breakup. A comparison with the data of a recent experiment is performed. It is shown that the extraction of the radiative capture cross sections $^7Be(p,\ \gamma)^8B$ which are relevant for the solar neutrino problem is not affected appreciably by Coulomb reacceleration. A non-perturbative model is used for the purpose. Emphasis is put on the perspectives for future experiments which are planned at the University of Notre Dame, RIKEN (Japan), and GSI (Germany). An analysis of the total yields of ``photon-point" processes in inelastic electron scattering is also done.Comment: 23 pages, plain Latex. 12 figures available upon request

Wave-vector dependence of spin and density multipole excitations in quantum dots

We have employed time-dependent local-spin density functional theory to analyze the multipole spin and charge density excitations in GaAs-AlGaAs quantum dots. The on-plane transferred momentum degree of freedom has been taken into account, and the wave-vector dependence of the excitations is discussed. In agreement with previous experiments, we have found that the energies of these modes do not depend on the transferred wave-vector, although their intensities do. Comparison with a recent resonant Raman scattering experiment [C. Sch\"uller et al, Phys. Rev. Lett {\bf 80}, 2673 (1998)] is made. This allows to identify the angular momentum of several of the observed modes as well as to reproduce their energies.Comment: 14 pages in REVTEX and 14 postscript figure

Astrophysical S-factor of the 7^7Be(p,γ)8p,\gamma)^8B reaction from Coulomb dissociation of 8^8B

The Coulomb dissociation method to obtain the astrophysical S-factor, $S_{17}(0)$, for the $^7$Be($p,\gamma)^8$B reaction at solar energies is investigated by analysing the recently measured data on the breakup reaction $^{208}$Pb$(^8$B,$^7$Be$~p)^{208}$Pb at 46.5 MeV/A beam energy. Breakup cross sections corresponding to E1, $E2$ and $M1$ transitions are calculated with a theory of Coulomb excitation that includes the effects of the Coulomb recoil as well as relativistic retardation. The interplay of nuclear and Coulomb contributions to the breakup process is studied by performing a full quantum mechanical calculation within the framework of the distorted-wave Born Approximation. In the kinematical regime of the present experiment, both nuclear as well as Coulomb-nuclear interference processes affect the pure Coulomb breakup cross sections very marginally. The $E2$ cross sections are strongly dependent on the model used to describe the structure of $^8$B. The value of $S_{17}(0)$ is deduced with and without $E2$ and $M1$ contributions added to the $E1$ cross sections and the results are discussed.Comment: 10 pages, with 4 figures included with psfig; Physics Letters B, in pres

Dynamical simulation of DCC formation in Bjorken rods

Using a semi-classical treatment of the linear sigma model, we simulate the dynamical evolution of an initially hot cylindrical rod endowed with a longitudinal Bjorken scaling expansion (a ``Bjorken rod''). The field equation is propagated until full decoupling has occurred and the asymptotic many-body state of free pions is then obtained by a suitable Fourier decomposition of the field and a subsequent stochastic determination of the number of quanta in each elementary mode. The resulting transverse pion spectrum exhibits visible enhancements below 200 MeV due to the parametric amplification caused by the oscillatory relaxation of the chiral order parameter. Ensembles of such final states are subjected to various event-by-event analyses. The factorial moments of the multiplicity distribution suggest that the soft pions are non-statistical. Furthermore, their emission patterns exhibit azimuthal correlations that have a bearing on the domain size in the source. Finally, the distribution of the neutral pion fraction shows a significant broadening for the soft pions which grows steadily as the number of azimuthal segments is increased. All of these features are indicative of disoriented chiral condensates and it may be interesting to apply similar analyses to actual data from high-energy nuclear collision experiments.Comment: 38 pages total, incl 26 ps figures ([email protected]

Electromagnetic Modes in Deformed Nuclei

A strength function method is adopted to describe a coupling between electric and magnetic modes of different multipolarity. The collective vibrations are analysed for a separable residual interaction in the framework of the random-phase approximation. The coupling between $M2$ and $E1$ giant resonances is considered as an illustrative example.Comment: 7 pages (latex), 1 figure (ps file), an invited talk at the workshop "Symmetries and Spin - Praha 98", to be published in Czech.J.Phys., 199