14,704 research outputs found

    Superconducting fluctuations in small grains - the Universal Hamiltonian and the reduced BCS model

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    Small superconducting grains are discussed in the frameworks of both the reduced BCS Hamiltonian and the Universal Hamiltonian. It is shown that fluctuations of electrons in levels far from the Fermi energy dominate superconducting properties in small and ultrasmall grains. Experimental consequences related to the spin susceptibility and persistent currents of grains and rings with weak electron-electron interactions are discussed.Comment: Contribution to the proceedings of "Fluctuations and phase transitions in superconductors", Nazareth Ilit, Israel, June 10-14, 200

    Explanatory Challenges in Metaethics

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    There are several important arguments in metaethics that rely on explanatory considerations. Gilbert Harman has presented a challenge to the existence of moral facts that depends on the claim that the best explanation of our moral beliefs does not involve moral facts. The Reliability Challenge against moral realism depends on the claim that moral realism is incompatible with there being a satisfying explanation of our reliability about moral truths. The purpose of this chapter is to examine these and related arguments. In particular, this chapter will discuss four kinds of arguments – Harman’s Challenge, evolutionary debunking arguments, irrelevant influence arguments, and the Reliability Challenge – understood as arguments against moral realism. The main goals of this chapter are (i) to articulate the strongest version of these arguments; (ii) to present and assess the central epistemological principles underlying these arguments; and (iii) to determine what a realist would have to do to adequately respond to these arguments

    Self-Consciousness and 'Split' Brains: The Mind's I

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    Elizabeth Schechter explores the implications of the experience of people who have had the pathway between the two hemispheres of their brain severed, and argues that there are in fact two minds, subjects of experience, and intentional agents inside each split-brain human being: right and left. But each split-brain subject is still one of us

    Possible Extension of the Chiral Perturbation Theory Program

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    After a brief discussion of how chiral dynamics has evolved from the ``universal V-A theory of weak interactions'', we present some evidence that symmetry breaking for the vector meson multiplet is not simpler than but rather analogous to that for the pseudoscalar multiplet. This provides a motivation for speculating on how to extend in a systematic way the chiral perturbation theory program to include vectors.Comment: Contribution to Marshak Memorial Volume, edited by E.C.G. Sudarshan, to be published by World Scientific, Singapore 1994, PREPRINT SU-4240-57

    Small Steps and Great Leaps in Thought: The Epistemology of Basic Deductive Rules

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    We are justified in employing the rule of inference Modus Ponens (or one much like it) as basic in our reasoning. By contrast, we are not justified in employing a rule of inference that permits inferring to some difficult mathematical theorem from the relevant axioms in a single step. Such an inferential step is intuitively “too large” to count as justified. What accounts for this difference? In this paper, I canvass several possible explanations. I argue that the most promising approach is to appeal to features like usefulness or indispensability to important or required cognitive projects. On the resulting view, whether an inferential step counts as large or small depends on the importance of the relevant rule of inference in our thought

    Introduction to effective Lagrangians for QCD

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    A brief introduction to the effective Lagrangian treatment of QCD (in the sense of using fields representing physical particles rather than quarks and gluons) will be given. The historical evolution of the subject will be discussed. Some background material related to a recent model for Gamma Ray Bursters will be given. Finally, some recent work on low energy strong interactions will be mentioned.Comment: 12 pages, 2 figures, talk at "Compact stars in the QCD phase diagram", Copenhagen, Aug. 15-18, 200

    Difficult Cases and the Epistemic Justification of Moral Belief

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    This paper concerns the epistemology of difficult moral cases where the difficulty is not traceable to ignorance about non-moral matters. The paper first argues for a principle concerning the epistemic status of moral beliefs about difficult moral cases. The basic idea behind the principle is that one’s belief about the moral status of a potential action in a difficult moral case is not justified unless one has some appreciation of what the relevant moral considerations are and how they bear on the moral status of the potential action. The paper then argues that this principle has important ramifications for moral epistemology and moral metaphysics. It puts pressure on some views of the justification of moral belief, such as ethical intuitionism and reliabilism. It puts pressure on some antirealist views of moral metaphysics, including simple versions of relativism. It also provides some direct positive support for broadly realist views of morality

    A potential test of the CP properties and Majorana nature of neutrinos

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    The scattering of solar neutrinos on electrons may reveal their CP properties, which are particularly sensitive to their Majorana nature. The cross section is sensitive to the neutrino dipole moments through an interference of electro-magnetic and weak amplitudes. We show how future solar neutrino experiments with good angular resolution and low energy threshold, such as Hellaz, can be sensitive to the resulting azimuthal asymmetries in event number, and could therefore provide valuable information on the CP properties and the nature of the neutrinos, provided the solar magnetic field direction is fixed.Comment: 14 pages, 1 figure, eq. (19) corrected. Version to be publishe
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