Hasil untuk "cond-mat.other"

D. Hollander, Jennifer R. Worley, M. Asoodeh et al.

Yuji Kobayashi, J. Kubo, A. Matsuo et al.

G. Dedkov, A. A. Kyasov

We calculate heating rate, attractive conservative and tangential dissipative fluctuation electromagnetic forces felt by a thick plate moving with nonrelativistic velocity parallel to a closely spaced another plate in rest using relativistic fluctuation electrodynamics. We argue that recently developed relativistic out of equilibrium theory of fluctuation electromagnetic interactions [A.I. Volokitin, B.N.J. Persson, Phys. Rev. B78 (2008) 155437; arXiv:/cond-mat.other/0807.1004v1, 2008] has serious drawbacks.

M. Chertkov, V. Chernyak, R. Teodorescu

We discuss a generic model of Bayesian inference with binary variables defined on edges of a planar graph. The Loop Calculus approach of Chertkov and Chernyak (2006 Phys. Rev. E 73 065102(R) [cond-mat/0601487]; 2006 J. Stat. Mech. P06009 [cond-mat/0603189]) is used to evaluate the resulting series expansion for the partition function. We show that, for planar graphs, truncating the series at single-connected loops reduces, via a map reminiscent of the Fisher transformation (Fisher 1961 Phys. Rev. 124 1664), to evaluating the partition function of the dimer-matching model on an auxiliary planar graph. Thus, the truncated series can be easily re-summed, using the Pfaffian formula of Kasteleyn (1961 Physics 27 1209). This allows us to identify a big class of computationally tractable planar models reducible to a dimer model via the Belief Propagation (gauge) transformation. The Pfaffian representation can also be extended to the full Loop Series, in which case the expansion becomes a sum of Pfaffian contributions, each associated with dimer matchings on an extension to a subgraph of the original graph. Algorithmic consequences of the Pfaffian representation, as well as relations to quantum and non-planar models, are discussed.

V. Kravets, D. Bozec, J. Matthew et al.

M. Lee, M. Alcoutlabi, J. Magda et al.

K. Kanki, Hiroshi Kontani

This is a reply to the comment by O. Narikiyo (cond-mat/0012505) on our paper J. Phys. Soc. Jpn. {\bf 68}, (1999) 1614. We point out mistakes about his arguments, and we show that our analysis is compatible with the established Fermi liquid theory, so the obtained result is justified.

Z. Xiao, O. Dogru, E. Andrei et al.

P. Sindzingre, J. Fouet, C. Lhuillier

Exact diagonalizations indicate that the effective 1-dimensional behavior (sliding Luttinger liquid phase) of the frustrated spin-1/2 crossed chain model, predicted by Starykh, Singh and Levine [Phys. Rev. Lett. 88, 167203 (2002)], persists for a wide range of transverse couplings. The extension of the other phases (plaquette valence bond crystal and Neel long range order) is precised. No clear indication of a coexistence of these two phases is found, at variance with a suggestion of Sachdev and Park (cond-mat/0108214).

M. Takigawa, O. Starykh, A. Sandvik et al.

The NMR relaxation data on Sr_2CuO_3 [Phys. Rev. Lett. 76, 4612 (1996)] are reexamined and compared with the analytic theory of the dynamic susceptibility in the S=1/2 antiferromagnetic Heisenberg chain including multiplicative logarithmic corrections [Phys. Rev. Lett. 78, 539 (1997); cond-mat/9610015]. Comparisons of the spin-lattice and the gaussian spin-echo decay rates (1/T_1 and 1/T_{2G}) and their ratio all show good quantitative agreement. Our results demonstrate the importance of the logarithmic corrections in the analysis of experimental data for quasi-1D systems and indicate that the dynamics of Sr_2CuO_3 is well described by a S=1/2 one-dimensional Heisenberg model with a nearest neighbor exchange.

S. Korshunov

T. Ghosh, K. Machida

The work by T. K. Ghosh and K. Machida [Phys. Rev. A 73, 013613 (2006) and cond-mat/0510160] on the sound velocity in a cylindrically confined Fermi superfluid obeying a power-law equation of state is shown to make use of an improper projection of the sound wave equation. This inaccuracy fully accounts for the difference between their results and those previously reported by Capuzzi et al. [Phys. Rev. A 73, 021603(R) (2006) and cond-mat/0509323]. In this Comment, we show that both approaches lead exactly to the same result when the correct weight function is used in the projection. Plots of the correct behavior of the phonon and monopole-mode spectra in the BCS and unitary limits and in the BEC regime are also shown.

M. Cazalilla, J. Marston

Reply to the Comment of Luo, Xiang, and Wang, cond-mat/0212580.

V. Gurarie, E. Rezayi

We continue the program started in cond-mat/9809384 and explain the statistics of the excitations for the generalizations of the paired states in the quantum Hall effect in terms of the parafermion statistics. We show that these excitations behave as combinations of bosons and parafermions. That generalizes the prior treatment of the paired (Pfaffian) state where the excitations behave as combinations of bosons and fermions. We explain what it means, from a quantum mechanical point of view, for a particle to be a `parafermion' rather than a boson or a fermion and work through several explicit examples. The resulting multiplets coincide exactly with the angular momentum multiplets found numerically for the $k+1$ particle interaction Hamiltonian on a sphere. We also present a proof that the wave functions found in cond-mat/9809384 are indeed the correlation functions of the parafermion conformal field theory.

M. Valín-Rodríguez, A. Puente, L. Serra

4 pages (final publisher version), 9 pages, 3 figures (attached post-print version).-- PACS nrs.: 73.21.La, 73.21.-b.-- Pre-print version available at ArXiv: http://arxiv.org/abs/cond-mat/0311077.

F. Oppen, B. Halperin, Ady Stern

We study the transport properties of pinned striped quantum Hall phases. We show that, under quite general assumptions, the macroscopic conductivity tensor satisfies a semicircle law. In particular, this result is valid for both smectic and nematic stripe phases, independent of the presence of topological and orientational defects such as dislocations and grain boundaries. As a special case, our results explain the experimental validity of a product rule for the dissipative part of the resistivity tensor, which was previously derived by MacDonald and Fisher (cond-mat/9907278) for a perfect stripe structure.

F. Malet, M. Pi, M. Barranco et al.

4 pages.-- PACS numbers: 73.21.-b, 73.22.-f, 71.15.Mb.-- ArXiv pre-print: http://arxiv.org/abs/cond-mat/0610841.-- Final full-text version of the paper available at: http://dx.doi.org/10.1103/PhysRevB.74.193309.

D. F. Martinez, R. Molina

4 pages, 4 figures.--PACS nrs.: 72.15.Rn; 73.20.Fz; 73.21.Hb.--ArXiv pre-print available at: http://arxiv.org/abs/cond-mat/0511202v1

F. Sattin, Consorzio Rfx

In this paper we give an interpretation of Tsallis' nonextensive statistical mechanics based upon the information-theoretic point of view of Luzzi et al [cond-mat/0306217, cond-mat/0306247, cond-mat/0307325], suggesting Tsallis entropy to be not a fundamental concept but a derived one, stemming from an incomplete knowledge of the system, not taking properly into account its interaction with the environment. This interpretation seems to avoid some problems occurring with the original interpretation of Tsallis statistics.