Convergence of CI single center calculations of positron-atom interactions

The Configuration Interaction (CI) method using orbitals centered on the nucleus has recently been applied to calculate the interactions of positrons interacting with atoms. Computational investigations of the convergence properties of binding energy, phase shift and annihilation rate with respect to the maximum angular momentum of the orbital basis for the e^+Cu and PsH bound states, and the e^+-H scattering system were completed. The annihilation rates converge very slowly with angular momentum, and moreover the convergence with radial basis dimension appears to be slower for high angular momentum. A number of methods of completing the partial wave sum are compared, an approach based on a Delta X_J = a/(J + 1/2)^n + b/(J + 1/2)^(n+1) form (with n = 4 for phase shift (or energy) and n = 2 for the annihilation rate) seems to be preferred on considerations of utility and underlying physical justification.Comment: 23 pages preprint RevTeX, 11 figures, submitted to PR

Low energy electron energy-loss spectroscopy of CF₃X (X=Cl,Br)

We report threshold electron energy-loss spectra for the fluorohalomethanes CFC₃X (X=Cl,Br). Measurements were made at incident electron energies of 30 and 100 eV in energy-loss range of 4-14 eV, and at scattering angles of 4 degrees and 15 degrees. Several new electronic transitions are observed which are ascribable to excitation of low-lying states as well as are intrinsically overlapped in the molecules themselves. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-section measurements, high-energy scattering spectra, and ab initio molecular orbital calculations. The calculated potential curves along the C-X bond show repulsive nature, suggesting that these transitions may lead to dissociation of the C-X bond. The present results are also compared with the previous ones for CF₃H, CF₄, and CF₃I.This work was performed with the support and under the auspices of the CUP, the IAEA’s Co-ordinated Research Program, MEXT, and JAEA. One of the authors C.M. had been also thankful to the Japan Society for Promotion of Science for financial support under Grant No. P04064. One of the authors L.P. also acknowledges partial support by the Academic Frontier Program of MEXT. One of the authors H.C. acknowledges the support from the Korea Research Foundation 2006-311-C00031

Knowledge and Normativity: A Matrix of Disciplines and Practices

This is the author accepted manuscript. The final version is available from Routledge via the link in this recordThis chapter introduces the matrix approach as a method of studying the life sciences. It builds on insights from the philosophy and sociology of science over the past decades against which it is laid out. The contribution of this new approach is that it reconfigures the life sciences as multidisciplinary and multi-institutional societal projects. The case study of stem cell research shows that one cannot separate internal and external, that is epistemic, social, ethical, and political factors affecting the development of a life science. The matrix approach allows for the examination of this complex and dynamic web of interests and societal practices and highlights the important role of legal, normative, technical and political conditions and activities in making the science work in specific ways. Life sciences operate in a matrix of diverse societal intersections and spheres of dominance. The approach especially reframes the role and scope of the humanities and social sciences. It prepares the ground for a self-critical reflection in bioethics, social sciences, and philosophy. These disciplines do not just analyse stem cell research as an object, from a distance, they co-configure it and shape its contemporary gestalt and practices.German Federal Ministry of Education and Research (BMBF)Bavarian State Ministry of Science and the ArtsUniversity of Exete

K^+ -> pi^+pi^0e^+e^-: a novel short-distance probe

We study the decay K^+ -> pi^+ pi^0 e^+ e^-, currently under analysis by the NA62 Collaboration at CERN. In particular, we provide a detailed analysis of the Dalitz plot for the long-distance, gamma^*-mediated, contributions (Bremsstrahlung, direct emission and its interference). We also examine a set of asymmetries to isolate genuine short-distance effects. While we show that charge asymmetries are not required to test short distances, they provide the best environment for its detection. This constitutes by itself a strong motivation for NA62 to study K^- decays in the future. We therefore provide a detailed study of different charge asymmetries and the corresponding estimated signals. Whenever possible, we make contact with the related processes K^+ -> pi^+ pi^0 gamma and K_L -> pi^+ pi^- e^+ e^- and discuss the advantages of K^+ -> pi^+ pi^0 e^+ e^- over them.Comment: 25 pages, 6 figure

Hamburg's Spaces of Danger: Race, Violence and Memory in a Contemporary Global City

Germany today is experiencing the strongest upsurge of right-wing populism since the second world war, most notably with the rise of Pegida and Alternative für Deutschland. Yet wealthy global cities like Hamburg continue to present themselves as the gatekeepers of liberal progress and cosmopolitan openness. This article argues that Hamburg’s urban boosterism relies on, while simultaneously obscuring, the same structures of racial violence that embolden reactionary movements. Drawing on the work of Walter Benjamin and Allan Pred, we present an archaeology of Hamburg’s landscape, uncovering some of its ‘spaces of danger’––sites layered with histories of violence, many of which lie buried and forgotten. We find that these spaces, when they become visible, threaten to undermine Hamburg’s cosmopolitan narrative. They must, as a result, be continually erased or downplayed in order to secure the city as an attractive site for capital investment. To illustrate this argument, we give three historical examples: Hamburg’s role in the Hanseatic League during the medieval and early modern period; the city under the Nazi regime; and the recent treatment of Black African refugees. The article’s main contribution is to better situate issues of historical landscape, collective memory and racialized violence within the political economy of today’s global city

CP-violation in K_{S,L}->\pi^{+}\pi^{-}\gamma and K_{S,L}->\pi^{+}\pi^{-}e^{+}e^{-} decays

The dependence of K_{S,L}->\pi^{+}\pi^{-}\gamma decay probabilities on photon polarization is calculated. The phases of terms of amplitude that arise from the pion-pion interaction are obtained by using a simple realistic model of pion-pion interaction via virtual \rho-meson, instead of the ChPT. The results are compared with those of other authors and the origin of slight discrepancies is explained. It is shown that the standard ChPT approach for K_{S,L}-> \pi^{+}\pi^{-}\gamma decays cannot reproduce the contribution of the \rho-meson to the P-wave \pi\pi interaction. The departure of the photon spectrum from pure bremsstrahlung due to the pion loop contribution to the direct emission amplitude is calculated. It is shown that the interference between the terms of amplitude with different CP-parity appears only when the photon is polarized (linearly or circularly). Instead of measuring the linear polarization, the angular correlation between the \pi^{+}\pi^{-} and e^{+}e^{-} planes in K_{S,L}->\pi^{+}\pi^{-}e^{+}e^{-} decay can be studied.Comment: 32 pages, 10 figures, 1 table, LaTex ; added figure, the comparison with ChPT revise

First observation and study of the K± → π±π0e+e− decay

The NA48/2 experiment at CERN reports the first observation of the K±→π±π0e+e− decay from an exposure of 1.7×1011 charged kaon decays recorded in 2003-2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region, BR(K±→π±π0e+e−)=(4.24±0.14)×10−6. The study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated

Financial innovations and blockchain applications: New digital paradigms in global cybersociety

Cryptocurrencies—digital assets—are discussed from the viewpoint of the medium of exchange and the store of value with a focus on Bitcoin. The issue of trust towards the unit of accounts is viewed in the perspective of historical events including fiat currency reforms in the past all over the world. It is argued that a major test of the present global financial system and its emerging new technology alternatives has not occurred yet. The notion of intrinsic value of currency is strongly attached to the stability of the social and economic system, which landscape will be probably drastically altered in the next few decades due to the rise of artificial intelligence. The chapters in this book which are focusing on the current aspects of financial innovations also point out the possible directions and dilemmas the future may bring us