13 research outputs found

    On the finite-size behavior of systems with asymptotically large critical shift

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    Exact results of the finite-size behavior of the susceptibility in three-dimensional mean spherical model films under Dirichlet-Dirichlet, Dirichlet-Neumann and Neumann-Neumann boundary conditions are presented. The corresponding scaling functions are explicitly derived and their asymptotics close to, above and below the bulk critical temperature TcT_c are obtained. The results can be incorporated in the framework of the finite-size scaling theory where the exponent λ\lambda characterizing the shift of the finite-size critical temperature with respect to TcT_c is smaller than 1/ν1/\nu, with ν\nu being the critical exponent of the bulk correlation length.Comment: 24 pages, late

    On the Finite-Temperature Generalization of the C-theorem and the Interplay between Classical and Quantum Fluctuations

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    The behavior of the finite-temperature C-function, defined by Neto and Fradkin [Nucl. Phys. B {\bf 400}, 525 (1993)], is analyzed within a d -dimensional exactly solvable lattice model, recently proposed by Vojta [Phys. Rev. B {\bf 53}, 710 (1996)], which is of the same universality class as the quantum nonlinear O(n) sigma model in the limit nn\to \infty. The scaling functions of C for the cases d=1 (absence of long-range order), d=2 (existence of a quantum critical point), d=4 (existence of a line of finite temperature critical points that ends up with a quantum critical point) are derived and analyzed. The locations of regions where C is monotonically increasing (which depend significantly on d) are exactly determined. The results are interpreted within the finite-size scaling theory that has to be modified for d=4. PACS number(s): 05.20.-y, 05.50.+q, 75.10.Hk, 75.10.Jm, 63.70.+h, 05.30-d, 02.30Comment: 15 pages LATEX, ioplppt.sty file used, 6 EPS figures. Some changes made in section V (on finite-size scaling interpretation of the results obtained

    Exact Three Dimensional Casimir Force Amplitude, CC-function and Binder's Cumulant Ratio: Spherical Model Results

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    The three dimensional mean spherical model on a hypercubic lattice with a film geometry L×2L\times \infty ^2 under periodic boundary conditions is considered in the presence of an external magnetic field HH. The universal Casimir amplitude Δ\Delta and the Binder's cumulant ratio BB are calculated exactly and found to be Δ=2ζ(3)/(5π)0.153051\Delta =-2\zeta (3)/(5\pi)\approx -0.153051 and B=2π/(5ln3[(1+5)/2]).B=2\pi /(\sqrt{5}\ln ^3[(1+\sqrt{5})/2]). A discussion on the relations between the finite temperature CC-function, usually defined for quantum systems, and the excess free energy (due to the finite-size contributions to the free energy of the system) scaling function is presented. It is demonstrated that the CC-function of the model equals 4/5 at the bulk critical temperature TcT_c. It is analytically shown that the excess free energy is a monotonically increasing function of the temperature TT and of the magnetic field H|H| in the vicinity of Tc.T_c. This property is supposed to hold for any classical dd-dimensional O(n),n>2,O(n),n>2, model with a film geometry under periodic boundary conditions when d3d\leq 3. An analytical evidence is also presented to confirm that the Casimir force in the system is negative both below and in the vicinity of the bulk critical temperature Tc.T_c.Comment: 12 pages revtex, one eps figure, submitted to Phys. Rev E A set of references added with the text needed to incorporate them. Small changes in the title and in the abstrac

    BLOOM: A 176B-Parameter Open-Access Multilingual Language Model

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    Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License

    Theory of critical phenomena in finite-size systems: scaling and quantum effects

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    The aim of this book is to familiarise the reader with the rich collection of ideas, methods and results available in the theory of critical phenomena in systems with confined geometry. The existence of universal features of the finite-size effects arising due to highly correlated classical or quantum fluctuations is explained by the finite-size scaling theory. This theory (1) offers an interpretation of experimental results on finite-size effects in real systems; (2) gives the most reliable tool for extrapolation to the thermodynamic limit of data obtained by computer simulations; (3) reveal

    Teaching and research on the Cold War in the United Kingdom

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