24,890 research outputs found

    The Formation of Classical Defects After a Slow Quantum Phase Transition

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    Classical defects (monopoles, vortices, etc.) are a characteristic consequence of many phase transitions of quantum fields. We show a model in which the onset of classical probability distributions, for the long-wavelength modes at early times, allows the identification of line-zeroes of the field with vortex separation. We obtain a refined version of Kibble's causal results for defect separation, but from a completely different approach. It is apparent that vortices are not created from thermal fluctuations in the Ginzburg regime.Comment: 10 pages, RevTex file. No figures. To appear in Phys. Lett.

    Noise-induced energy excitation by a general environment

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    We analyze the effects that general environments, namely ohmic and non-ohmic, at zero and high temperature induce over a quantum Brownian particle. We state that the evolution of the system can be summarized in terms of two main environmental induced physical phenomena: decoherence and energy activation. In this article we show that the latter is a post-decoherence phenomenon. As the energy is an observable, the excitation process is a direct indication of the system-environment entanglement particularly useful at zero temperature.Comment: 14 pages; 7 figures. Version to appear in Phys Lett.

    Decoherence of domains and defects at phase transitions

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    In this further letter on the onset of classical behaviour in field theory due to a phase transition, we show that it can be phrased easily in terms of the decoherence functional, without having to use the master equation. To demonstrate this, we consider the decohering effects due to the displacement of domain boundaries, with implications for the displacement of defects, in general. We see that decoherence arises so quickly in this event, that it is negligible in comparison to decoherence due to field fluctuations in the way defined in our previous papers.Comment: Version published in Phys. Lett.

    An explicit open image theorem for products of elliptic curves

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    Let KK be a number field and E1,‚Ķ,EnE_1, \ldots, E_n be elliptic curves over KK, pairwise non-isogenous over K‚Äĺ\overline{K} and without complex multiplication over K‚Äĺ\overline{K}. We study the image of the adelic representation of the absolute Galois group of KK naturally attached to E1√ó‚čĮ√óEnE_1 \times \cdots \times E_n. The main result is an explicit bound for the index of this image in {(x1,‚Ķ,xn)‚ąąGL‚Ā°2(Z^)n‚ą£det‚Ā°xi=det‚Ā°xj‚ÄÖ‚Ää‚ÄÖ‚Ää‚ąÄi,j}\left\{ (x_1,\ldots,x_n) \in \operatorname{GL}_2(\hat{\mathbb{Z}})^n \bigm\vert \det x_i = \det x_j \;\; \forall i,j \right\}.Comment: 18 pages. v2: improved expositio
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