21,559 research outputs found

    Quantum Locality?

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    Robert Griffiths has recently addressed, within the framework of a 'consistent quantum theory' that he has developed, the issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over long distances. He argues that the putative proofs of this property that involve hidden variables include in their premises some essentially classical-physics-type assumptions that are fundamentally incompatible with the precepts of quantum physics. One cannot logically prove properties of a system by establishing, instead, properties of a system modified by adding properties alien to the original system. Hence Griffiths' rejection of hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by his 'consistent quantum theory' shows that the cited proof is valid within that restrictive version of quantum theory. An added section responds to Griffiths' reply, which cites general possibilities of ambiguities that make what is to be proved ill-defined, and hence render the pertinent 'consistent framework' ill defined. But the vagaries that he cites do not upset the proof in question, which, both by its physical formulation and by explicit identification, specify the framework to be used. Griffiths confirms the validity of the proof insofar as that framework is used. The section also shows, in response to Griffiths' challenge, why a putative proof of locality that he has described is flawed.Comment: This version adds a response to Griffiths' reply to my original. It notes that Griffiths confirms the validity of my argument if one uses the framework that I use. Griffiths' objection that other frameworks exist is not germaine, because I use the unique one that satisfies the explicitly stated conditions that the choices be macroscopic choices of experiments and outcomes in a specified orde

    The Contribution of Late-type/Irregulars to the Faint Galaxy Counts from HST Medium Deep Survey Images

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    We present a complete morphologically classified sample of 144 faint field galaxies from the HST Medium Deep Survey with 20.0 < I <22.0 mag. We compare the global properties of the ellipticals, early and late-type spirals, and find a non-negligible fraction (13/144) of compact blue [(V-I) < 1.0 mag] systems with r1/4r^{1/4}-profiles. We give the differential galaxy number counts for ellipticals and early-type spirals independently, and find that the data are consistent with no-evolution predictions based on conventional flat Schechter luminosity functions (LF's) and a standard cosmology. Conversely, late-type/Irregulars show a steeply rising differential number count with slope (δlogNδm)=0.64±0.1(\frac{\delta log N}{\delta m}) = 0.64\pm 0.1. No-evolution models based on the Loveday et al. (1992) and Marzke et al. (1994b) {\it local} luminosity functions under-predict the late-type/Irregular counts by 1.0 and 0.5 dex, respectively, at I = 21.75 mag. Examination of the Irregulars alone shows that 50\sim 50% appear inert and the remainder have multiple cores. If the inert galaxies represent a non-evolving late-type population, then a Loveday-like LF (α1.0\alpha\simeq -1.0) is ruled out for these types, and a LF with a steep faint-end (α1.5\alpha\simeq -1.5) is suggested. If multiple core structure indicates recent star-formation, then the observed excess of faint blue field galaxies is likely due to {\it evolutionary} processes acting on a {\it steep} field LF for late-type/Irregulars. The evolutionary mechanism is unclear, but 60% of the multiple-core Irregulars show close companions. To reconcile a Marzke-like LF with the faint redshift surveys, this evolution must be preferentially occurring in the brightest late-type galaxies with z > 0.5 at I = 21.75 mag.Comment: 29 pages, 1 catalog and 10 figures. The figures and catalog can be found at http://www.phys.unsw.edu.au/~spd/bib.htm

    REGULAR SUPPRESSION OF P,T-VIOLATING NUCLEAR MATRIX ELEMENTS

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    In heavy nuclei there is a parametrical suppression,   A1/3  \;\sim A^{-1/3}\;, of T-odd, P-odd matrix elements as compared to T-even, P-odd ones.Comment: 3 page

    Geometry of Universal Magnification Invariants

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    Recent work in gravitational lensing and catastrophe theory has shown that the sum of the signed magnifications of images near folds, cusps and also higher catastrophes is zero. Here, it is discussed how Lefschetz fixed point theory can be used to interpret this result geometrically. It is shown for the generic case as well as for elliptic and hyperbolic umbilics in gravitational lensing.Comment: RevTEX4, 13 pages, submitted to J. Math. Phy

    Optimal Eavesdropping in Quantum Cryptography. II. Quantum Circuit

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    It is shown that the optimum strategy of the eavesdropper, as described in the preceding paper, can be expressed in terms of a quantum circuit in a way which makes it obvious why certain parameters take on particular values, and why obtaining information in one basis gives rise to noise in the conjugate basis.Comment: 7 pages, 1 figure, Latex, the second part of quant-ph/970103

    Introduction to Arithmetic Mirror Symmetry

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    We describe how to find period integrals and Picard-Fuchs differential equations for certain one-parameter families of Calabi-Yau manifolds. These families can be seen as varieties over a finite field, in which case we show in an explicit example that the number of points of a generic element can be given in terms of p-adic period integrals. We also discuss several approaches to finding zeta functions of mirror manifolds and their factorizations. These notes are based on lectures given at the Fields Institute during the thematic program on Calabi-Yau Varieties: Arithmetic, Geometry, and Physics

    Extent of simultaneous parity and time violation in 182W

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    In order to relate nuclear gamma-ray distributions to the fundamental parity-time- (PT-) and parity- (P-) violating meson-nucleon interaction, we analyze the case of the mixed (E1,M2,E3) 1189-keV gamma ray in 182W which is populated in the decay of cryogenically oriented 182Ta. Within the framework of the quasiparticle random-phase approximation we calculate the value of the complex ‘‘irregular’’ mixing ratio ɛ(E2¯/M2) for this transition. We estimate that this mixing ratio will have a P-violating real part of ‖ɛ‖cosη≃5×10-5 which implies an observable forward-backward asymmetry (〈J〉⋅k) in the 1189-keV gamma-ray directional distribution of OP≃2×10^-5 at 10 mK. For the PT-violating imaginary part we find ‖ɛ‖sinη≃200g̃ πNN(I=1), where g̃ πNN(I=1) is the strength of the isovector PT-violating pion-nucleon coupling. An upper limit to this constant of ≲3×10^-10 may be obtained from the electric dipole moment of the neutron. Whence we conclude that at 10 mK one needs to measure the PT-violating correlation (〈J〉⋅k2)(〈J〉⋅k1×k2) to an accuracy of OPT≲2×10^-8 in order to improve the limit on g̃ πNN(I=1) set by the neutron electric dipole moment

    P,T-Violating Nuclear Matrix Elements in the One-Meson Exchange Approximation

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    Expressions for the P,T-violating NN potentials are derived for π\pi, ρ\rho and ω\omega exchange. The nuclear matrix elements for ρ\rho and ω\omega exchange are shown to be greatly suppressed, so that, under the assumption of comparable coupling constants, π\pi exchange would dominate by two orders of magnitude. The ratio of P,T-violating to P-violating matrix elements is found to remain approximately constant across the nuclear mass table, thus establishing the proportionality between time-reversal-violation and parity-violation matrix elements. The calculated values of this ratio suggest a need to obtain an accuracy of order 5×104 5 \times 10^{-4} for the ratio of the PT-violating to P-violating asymmetries in neutron transmission experiments in order to improve on the present limits on the isovector pion coupling constant.Comment: 17 pages, LaTeX, no figure
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