Critical correlations and scaling windows
Research context
postgraduate concept · conditional · As of 2026-10-10
Connected order-parameter correlations define a correlation length ξ.
Key knowledge
Connected order-parameter correlations define a correlation length ξ. Near a continuous critical point, ξ∝|t|⁻ν and the critical correlator scales as r^(−d+2−η) within its scaling window, t=(T−T_c)/T_c. Gaussian theory gives ν=1/2 and η=0; fluctuation corrections depend on dimension, symmetry and interaction range.
Values and equations
t=(T−T_c)/T_c; ξ∝|t|^(−ν); G_c(r)∝r^(−d+2−η)
- T,T_c
- Temperature and transition temperature K
- t,ν,η,d
- Reduced temperature, exponents and spatial dimension
- ξ,r
- Correlation length and separation m
- G_c
- Connected correlator with units fixed by order-parameter normalization
Conditions and scope
- Thermodynamic-limit equilibrium scaling with microscopic distance≪r≪system size; nonzero-t correlations eventually decay beyond ξ.
- Finite size, disorder and long-range forces can change the observable regime or universality class. Fit corrections and window dependence rather than identify exponents from one slope.
Sources · 2
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Inspected §§2.2.2–2.3: connected correlations, Gaussian correlation length, critical exponents and Ginzburg criterion; source check dated 2026-10-10. Scope is limited to the cited statements, equations and assumptions, not the whole publication. Inspected §§3.1–3.4: coarse-graining, relevant directions, upper critical dimension and Wilson–Fisher expansion; source check dated 2026-10-10. Scope is limited to the cited statements, equations and assumptions, not the whole publication.
2026-10-10 · Author source inspection of the displayed claim, model assumptions and equations; independent exact-content and branch-inventory review is a separate gate. Contemporary status is a dated snapshot, not a promise of ongoing monitoring.
Entry details
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- research-physics-critical-correlations
- Revision
- research.1
- Structured reference record
- Postgraduate & research reference