The Experts below are selected from a list of 276 Experts worldwide ranked by ideXlab platform
Janos Balog - One of the best experts on this subject based on the ideXlab platform.
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test of asymptotic freedom and Scaling Hypothesis in the 2d o 3 sigma model
Nuclear Physics, 2003Co-Authors: Janos Balog, Peter WeiszAbstract:Abstract The 7-particle form factors of the fundamental spin field of the O(3) non-linear σ-model are constructed. We calculate the corresponding contribution to the spin–spin correlation function, and compare with predictions from the spectral density Scaling Hypothesis. The resulting approximation to the spin–spin correlation function agrees well with that computed in renormalized (asymptotically free) perturbation theory in the expected energy range. Further we observe simple lower and upper bounds for the sum of the absolute square of the form factors which may be of use for analytic estimates.
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Scaling Hypothesis for the spectral densities in the o 3 nonlinear sigma model
Physical Review Letters, 1997Co-Authors: Janos Balog, M NiedermaierAbstract:A Scaling Hypothesis for the n-particle spectral densities of the O(3) nonlinear sigma model is described. It states that for large n the n-particle spectral densities are {open_quotes}self-similar{close_quotes} in being rescaled copies of a universal shape function. Promoted to a working Hypothesis, it allows one to compute the two-point functions at all energy scales and yields exact values for two nonperturbative constants. Applied to nonintegrable perturbations of the model, the Hypothesis implies Scaling laws for multiparticle production processes analogous to Koba-Nielsen-Olesen Scaling in QCD. {copyright} {ital 1997} {ital The American Physical Society}
Daniel A Stariolo - One of the best experts on this subject based on the ideXlab platform.
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Coarse-grained models of stripe forming systems: phase diagrams, anomalies, and Scaling Hypothesis.
Physical review. E Statistical nonlinear and soft matter physics, 2012Co-Authors: Alejandro Mendoza-coto, Daniel A StarioloAbstract:Two coarse-grained models which capture some universal characteristics of stripe forming systems are studied. At high temperatures, the structure factors of both models attain their maxima on a circle in reciprocal space, as a consequence of generic isotropic competing interactions. Although this is known to lead to some universal properties, we show that the phase diagrams have important differences, which are a consequence of the particular k dependence of the fluctuation spectrum in each model. The phase diagrams are computed in a mean field approximation and also after inclusion of small fluctuations, which are shown to modify drastically the mean field behavior. Observables like the modulation length and magnetization profiles are computed for the whole temperature range accessible to both models and some important differences in behavior are observed. A stripe compression modulus is computed, showing an anomalous behavior with temperature as recently reported in related models. Also, a recently proposed Scaling Hypothesis for modulated systems is tested and found to be valid for both models studied.
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coarse grained models of stripe forming systems phase diagrams anomalies and Scaling Hypothesis
Physical Review E, 2012Co-Authors: Alejandro Mendozacoto, Daniel A StarioloAbstract:(Received 21 August 2012; published 26 November 2012)Twocoarse-grainedmodelswhichcapturesomeuniversalcharacteristicsofstripeformingsystemsarestudied.At high temperatures, the structure factors of both models attain their maxima on a circle in reciprocal space,as a consequence of generic isotropic competing interactions. Although this is known to lead to some universalproperties,weshowthatthephasediagramshaveimportantdifferences,whichareaconsequenceoftheparticulark dependence of the fluctuation spectrum in each model. The phase diagrams are computed in a mean fieldapproximation and also after inclusion of small fluctuations, which are shown to modify drastically the meanfield behavior. Observables like the modulation length and magnetization profiles are computed for the wholetemperature range accessible to both models and some important differences in behavior are observed. A stripecompression modulus is computed, showing an anomalous behavior with temperature as recently reported inrelated models. Also, a recently proposed Scaling Hypothesis for modulated systems is tested and found to bevalid for both models studied.DOI: 10.1103/PhysRevE.86.051130 PACS number(s): 64
R Pucci - One of the best experts on this subject based on the ideXlab platform.
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violation of the single parameter Scaling Hypothesis in disordered graphene nanoribbons
Physical Review B, 2008Co-Authors: Antonino La Magna, Ioannis Deretzis, Giuseppe Forte, R PucciAbstract:A numerical statistical analysis of the conductance $g$ distribution function in disordered graphene nanoribbons is presented. Calculations are performed within the nonequilibrium Green's Function formalism. We have checked that the conductance variance in these quasi one-dimensional systems scales linearly with the average of the logarithm of $g$, i.e., ${\ensuremath{\sigma}}^{2}=Al\ensuremath{-}\text{ln}\text{ }gg+B$ in the localization regime. However, the slope A is not a constant as the disorder degree varies in any region of the energy spectrum, i.e., the single parameters Scaling Hypothesis is not verified. Our results stimulate further investigations in order to categorize the conductance fluctuations on the basis of the band structure and/or lattice topology of the system in study.
M Niedermaier - One of the best experts on this subject based on the ideXlab platform.
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Scaling Hypothesis for the spectral densities in the o 3 nonlinear sigma model
Physical Review Letters, 1997Co-Authors: Janos Balog, M NiedermaierAbstract:A Scaling Hypothesis for the n-particle spectral densities of the O(3) nonlinear sigma model is described. It states that for large n the n-particle spectral densities are {open_quotes}self-similar{close_quotes} in being rescaled copies of a universal shape function. Promoted to a working Hypothesis, it allows one to compute the two-point functions at all energy scales and yields exact values for two nonperturbative constants. Applied to nonintegrable perturbations of the model, the Hypothesis implies Scaling laws for multiparticle production processes analogous to Koba-Nielsen-Olesen Scaling in QCD. {copyright} {ital 1997} {ital The American Physical Society}
I L Aleiner - One of the best experts on this subject based on the ideXlab platform.
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comment on anomalous conductance distribution in q1d gold wires possible violation of the one parameter Scaling Hypothesis
2004Co-Authors: Vladimir I Falko, I V Lerner, O Tsyplyatyev, I L AleinerAbstract:A Comment on the Letter by Pritiraj Mohanty and Richard A. Webb, Phys. Rev. Lett. 88, 146601 (2002). The authors of the Letter offer a Reply.
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comment on anomalous conductance distribution in quasi one dimensional gold wires possible violation of the one parameter Scaling Hypothesis
Physical Review Letters, 2004Co-Authors: Vladimir I Falko, I V Lerner, O Tsyplyatyev, I L AleinerAbstract:Mohanty and Webb [Phys. Rev. Lett. 88, 146601 (2002), cond-mat/0204298] claim that their data on conductance fluctuations in gold wires contradict the one-parameter Scaling. We show that flaws in extracting values of the cumulants (irreducible moments) > of the conductance distribution (for n=3,4) invalidate all the conclusions made there. The actual values of the cumulants determined by us from the published raw data contained in Ref. [Phys. Rev. Lett. 88, 146601 (2002)] are orders of magnitude smaller than those claimed. Moreover, the limited applicability of the ergodicity Hypothesis makes the higher order cumulants extracted from magnetofingerprints statistically unreliable. Thus, the data of Ref. [Phys. Rev. Lett. 88, 146601 (2002)] do not warrant any statement on the violation or validity of the one-parameter Scaling.
