33,337 research outputs found

    Recent developments in effective field theory

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    We will give a short introduction to the one-nucleon sector of chiral perturbation theory and will address the issue of a consistent power counting and renormalization. We will discuss the infrared regularization and the extended on-mass-shell scheme. Both allow for the inclusion of further degrees of freedom beyond pions and nucleons and the application to higher-loop calculations. As applications we consider the chiral expansion of the nucleon mass to order O(q^6) and the inclusion of vector and axial-vector mesons in the calculation of nucleon form factors.Comment: 8 pages, 6 figures, invited talk given at International School of Nuclear Physics, 29th Course "Quarks in Hadrons and Nuclei", Erice, Sicily, 16 - 24 September 200

    The Kuhnian mode of HPS

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    In this article I argue that a methodological challenge to an integrated history and philosophy of science approach put forth by Ron Giere almost forty years ago can be met by what I call the Kuhnian mode of History and Philosophy of Science (HPS). Although in the Kuhnian mode of HPS norms about science are motivated by historical facts about scientific practice, the justifiers of the constructed norms are not historical facts. The Kuhnian mode of HPS therefore evades the naturalistic fallacy which Giere’s challenge is a version of. Against the backdrop of a discussion of Laudan’s normative naturalism I argue that the Kuhnian mode of HPS is a superior form of naturalism which establishes contact to the practice of science without making itself dependent on its contingencies

    Interaction in the Bimodal Galaxy Cluster A3528

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    X-ray and radio continuum observations of the bimodal cluster A3528 in the Shapley Supercluster are presented. From a ROSAT PSPC pointed observation we find a marginal tendency of the intracluster gas to be hotter in the region between the two subclusters. This effect can be interpreted as the signature of interaction of the subclusters. We infer that the centres of the subclusters in A3528 will meet within a few 10^8 years. In continuum observations at 20cm and at 90cm with the Very Large Array we find four galaxies having radio emission. One of these galaxies shows a head-tail structure suggesting a motion of the galaxy through the intracluster medium. The radio tail shows an imbalance between the thermal pressure of the intra-cluster gas and the pressure of the relativistic electrons.Comment: 8 pages, postscript file including 7 figures, accepted for publication in M.N.R.A.

    Novelty, coherence, and Mendeleev's periodic table

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    Predictivism is the view that successful predictions of ‚Äėnovel‚Äô evidence carry more confirmational weight than accommodations of already known evidence. Novelty, in this context, has traditionally been conceived of as temporal novelty. However temporal predictivism has been criticized for lacking a rationale: why should the time order of theory and evidence matter? Instead, it has been proposed, novelty should be construed in terms of use-novelty, according to which evidence is novel if it was not used in the construction of a theory. Only if evidence is use-novel can it fully support the theory entailing it. As I point out in this paper, the writings of the most influential proponent of use-novelty contain a weaker and a stronger version of use-novelty. However both versions, I argue, are problematic. With regard to the appraisal of Mendeleev‚Äô periodic table, the most contentious historical case in the predictivism debate, I argue that temporal predictivism is indeed supported, although in ways not previously appreciated. On the basis of this case, I argue for a form of so-called symptomatic predictivism according to which temporally novel predictions carry more confirmational weight only insofar as they reveal the coherence of facts as identified by the theory as real
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