scholarly journals Critical Exponents for Long-Range $${O(n)}$$ O ( n ) Models Below the Upper Critical Dimension

2017 ◽  
Vol 358 (1) ◽  
pp. 343-436 ◽  
Author(s):  
Gordon Slade
Author(s):  
Tom Hutchcroft

AbstractWe study long-range Bernoulli percolation on $${\mathbb {Z}}^d$$ Z d in which each two vertices x and y are connected by an edge with probability $$1-\exp (-\beta \Vert x-y\Vert ^{-d-\alpha })$$ 1 - exp ( - β ‖ x - y ‖ - d - α ) . It is a theorem of Noam Berger (Commun. Math. Phys., 2002) that if $$0<\alpha <d$$ 0 < α < d then there is no infinite cluster at the critical parameter $$\beta _c$$ β c . We give a new, quantitative proof of this theorem establishing the power-law upper bound $$\begin{aligned} {\mathbf {P}}_{\beta _c}\bigl (|K|\ge n\bigr ) \le C n^{-(d-\alpha )/(2d+\alpha )} \end{aligned}$$ P β c ( | K | ≥ n ) ≤ C n - ( d - α ) / ( 2 d + α ) for every $$n\ge 1$$ n ≥ 1 , where K is the cluster of the origin. We believe that this is the first rigorous power-law upper bound for a Bernoulli percolation model that is neither planar nor expected to exhibit mean-field critical behaviour. As part of the proof, we establish a universal inequality implying that the maximum size of a cluster in percolation on any finite graph is of the same order as its mean with high probability. We apply this inequality to derive a new rigorous hyperscaling inequality $$(2-\eta )(\delta +1)\le d(\delta -1)$$ ( 2 - η ) ( δ + 1 ) ≤ d ( δ - 1 ) relating the cluster-volume exponent $$\delta $$ δ and two-point function exponent $$\eta $$ η .


1995 ◽  
Vol 09 (18) ◽  
pp. 1117-1121
Author(s):  
K. NOJIMA

The finite-size scaling property of the correlation length for the spherical model with long-range interaction is examined above the critical temperature. The analysis is performed below the upper critical dimension.


2017 ◽  
Vol 169 (6) ◽  
pp. 1132-1161 ◽  
Author(s):  
Martin Lohmann ◽  
Gordon Slade ◽  
Benjamin C. Wallace

Fractals ◽  
1993 ◽  
Vol 01 (04) ◽  
pp. 827-839 ◽  
Author(s):  
SERGEY V. BULDYREV ◽  
SHLOMO HAVLIN ◽  
JANOS KERTÉSZ ◽  
ARKADY SHEHTER ◽  
H. EUGENE STANLEY

We review recent numerical simulations of several models of interface growth in d- dimensional media with quenched disorder. These models belong to the universality class of anisotropic diode-resistor percolation networks. The values of the roughness exponent α=0.63±0.01 (d=1+1) and α=0.48±0.02 (d=2+1) are in good agreement with our recent experiments. We study also the diode-resistor percolation on a Cayley tree. We find that [Formula: see text] thus suggesting that the critical exponent for [Formula: see text]βp=∞ and that the upper critical dimension in this problem is d=dc=∞. Other critical exponents on the Cayley tree are: τ=3,ν||=ν⊥=γ=σ=0. The exponents related to roughness are: α=β=0, z=2.


Entropy ◽  
2019 ◽  
Vol 21 (10) ◽  
pp. 978
Author(s):  
Ian A. Campbell ◽  
Per H. Lundow

In addition to the standard scaling rules relating critical exponents at second order transitions, hyperscaling rules involve the dimension of the model. It is well known that in canonical Ising models hyperscaling rules are modified above the upper critical dimension. It was shown by M. Schwartz in 1991 that hyperscaling can also break down in Ising systems with quenched random interactions; Random Field Ising models, which are in this class, have been intensively studied. Here, numerical Ising Spin Glass data relating the scaling of the normalized Binder cumulant to that of the reduced correlation length are presented for dimensions 3, 4, 5, and 7. Hyperscaling is clearly violated in dimensions 3 and 4, as well as above the upper critical dimension D = 6 . Estimates are obtained for the “violation of hyperscaling exponent” values in the various models.


2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Marco Panero ◽  
Antonio Smecca

Abstract We present a high-precision Monte Carlo study of the classical Heisenberg model in four dimensions. We investigate the properties of monopole-like topological excitations that are enforced in the broken-symmetry phase by imposing suitable boundary conditions. We show that the corresponding magnetization and energy-density profiles are accurately predicted by previous analytical calculations derived in quantum field theory, while the scaling of the low-energy parameters of this description questions an interpretation in terms of particle excitations. We discuss the relevance of these findings and their possible experimental applications in condensed-matter physics.


1984 ◽  
Vol 55 (6) ◽  
pp. 1646-1648 ◽  
Author(s):  
Susan R. McKay ◽  
A. Nihat Berker

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