What is the definition of correlation and coupling?

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Coupling refers to the interaction between particles in a system, particularly in the context of statistical mechanics. Correlation, on the other hand, can arise from symmetries within the system, even in the absence of direct interactions. Both concepts are crucial for understanding the behavior of systems with millions of particles, such as charged or magnetic particles. While coupling involves direct influences among particles, correlation can indicate a statistical relationship that does not require explicit interactions. Understanding these definitions is essential for analyzing complex particle systems effectively.
lsloneil
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When dealing with system containing millions of particles( for example, charged particles or magnetic particles) with statistical mechanics, I may often see the description or explanation that the certain effect is due to the coupling or correlation of particles. So can anybody give me a specific definition of coupling and correlation? Does coupling or correlation simply mean the interaction between particles?

Thanks a lot!
 
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Coupling means interaction.
Correlation can occur because of symmetries without explicit interaction.
 
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