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Effective Field Theories Jonathan Bain

Summary: 1
Effective Field Theories
Jonathan Bain
Humanities and Social Sciences
Polytechnic Institute of New York University
Brooklyn, NY 11201
Abstract: An effective field theory (EFT) of a physical system is a theory of the dynamics of the system
at energies small compared to a given cutoff. For some systems, low-energy states with respect to this
cutoff are effectively independent of ("decoupled from") states at high energies. Hence one may study the
low-energy sector of the theory without the need for a detailed description of the high-energy sector.
Systems that admit EFTs appear in both relativistic quantum field theory (RQFT) and condensed matter
physics. In some cases, the high-energy theory is known and the effective theory may be obtained by a
process in which high-energy effects are systematically eliminated. In other cases, the high-energy theory
may not be known, and the effective theory may then be obtained by imposing symmetry and
"naturalness" constraints on candidate Langrangians. Many physicists currently believe that the Standard
Model of particle physics is an example of such a bottom-up EFT. In both cases, the nature of the
intertheoretic relation between an EFT and its (possibly hypothetical) high-energy theory is complex and
arguably cannot be described in terms of standard accounts of reduction. This essay provides a review of
this relation and what it suggests about the ontological status of EFTs and the extent to which the notion
of emergence can be associated with them.


Source: Aronov, Boris - Department of Computer and Information Science, Polytechnic University


Collections: Computer Technologies and Information Sciences