430,741 research outputs found
Challenges in Hadron Physics
In this talk, I address some open problems in hadron physics and stress their
importance for a better understanding of QCD in the confinement regime.Comment: Outlook talk at MESON 2004, Krakow, Poland, June 4-8, 2004, typos
correcte
Reply on the ``Comment on `Loss-error compensation in quantum- state measurements' ''
The authors of the Comment [G. M. D'Ariano and C. Macchiavello to be
published in Phys. Rev. A, quant-ph/9701009] tried to reestablish a 0.5
efficiency bound for loss compensation in optical homodyne tomography. In our
reply we demonstrate that neither does such a rigorous bound exist nor is the
bound required for ruling out the state reconstruction of an individual system
[G. M. D'Ariano and H. P. Yuen, Phys. Rev. Lett. 76, 2832 (1996)].Comment: LaTex, 2 pages, 1 Figure; to be published in Physical Review
Perfect 3-Dimensional Lattice Actions for 4-Dimensional Quantum Field Theories at Finite Temperature
We propose a two-step procedure to study the order of phase transitions at
finite temperature in electroweak theory and in simplified models thereof. In a
first step a coarse grained free energy is computed by perturbative methods. It
is obtained in the form of a 3-dimensional perfect lattice action by a block
spin transformation. It has finite temperature dependent coefficients. In this
way the UV-problem and the infrared problem is separated in a clean way. In the
second step the effective 3-dimensional lattice theory is treated in a
nonperturbative way, either by the Feynman-Bogoliubov method (solution of a gap
equation), by real space renormalization group methods, or by computer
simulations. In this paper we outline the principles for -theory
and scalar electrodynamics. The Ba{\l}aban-Jaffe block spin transformation for
the gauge field is used. It is known how to extend this transformation to the
nonabelian case, but this will not be discussed here.Comment: path to figures (in added uu-file) revised, no other changes 33
pages, 3 figures, late
On everywhere divergence of the strong -means of Walsh-Fourier series
Almost everywhere strong exponential summability of Fourier series in Walsh
and trigonometric systems established by Rodin in 1990. We prove, that if the
growth of a function is bigger than the
exponent, then the strong -summability of a Walsh-Fourier series can fail
everywhere. The analogous theorem for trigonometric system was proved before by
one of the author of this paper.Comment: 8 page
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