Statistical field theory

Last updated

In theoretical physics, statistical field theory (SFT) is a theoretical framework that describes phase transitions. [1] It does not denote a single theory but encompasses many models, including for magnetism, superconductivity, superfluidity, [2] topological phase transition, wetting [3] [4] as well as non-equilibrium phase transitions. [5] A SFT is any model in statistical mechanics where the degrees of freedom comprise a field or fields. In other words, the microstates of the system are expressed through field configurations. It is closely related to quantum field theory, which describes the quantum mechanics of fields, and shares with it many techniques, such as the path integral formulation and renormalization. If the system involves polymers, it is also known as polymer field theory.

Contents

In fact, by performing a Wick rotation from Minkowski space to Euclidean space, many results of statistical field theory can be applied directly to its quantum equivalent.[ citation needed ] The correlation functions of a statistical field theory are called Schwinger functions, and their properties are described by the Osterwalder–Schrader axioms.

Statistical field theories are widely used to describe systems in polymer physics or biophysics, such as polymer films, nanostructured block copolymers [6] or polyelectrolytes. [7]

Notes

  1. Le Bellac, Michel (1991). Quantum and Statistical Field Theory. Oxford: Clarendon Press. ISBN   978-0198539643.
  2. Altland, Alexander; Simons, Ben (2010). Condensed Matter Field Theory (2nd ed.). Cambridge: Cambridge University Press. ISBN   978-0-521-76975-4.
  3. Rejmer, K.; Dietrich, S.; Napiórkowski, M. (1999). "Filling transition for a wedge". Phys. Rev. E. 60 (4): 4027–4042. arXiv: cond-mat/9812115 . Bibcode:1999PhRvE..60.4027R. doi:10.1103/PhysRevE.60.4027. PMID   11970240. S2CID   23431707.
  4. Parry, A.O.; Rascon, C.; Wood, A.J. (1999). "Universality for 2D Wedge Wetting". Phys. Rev. Lett. 83 (26): 5535–5538. arXiv: cond-mat/9912388 . Bibcode:1999PhRvL..83.5535P. doi:10.1103/PhysRevLett.83.5535. S2CID   119364261.
  5. Täuber, Uwe (2014). Critical Dynamics. Cambridge: Cambridge University Press. ISBN   978-0-521-84223-5.
  6. Baeurle SA, Usami T, Gusev AA (2006). "A new multiscale modeling approach for the prediction of mechanical properties of polymer-based nanomaterials". Polymer. 47 (26): 8604–8617. doi:10.1016/j.polymer.2006.10.017.
  7. Baeurle SA, Nogovitsin EA (2007). "Challenging scaling laws of flexible polyelectrolyte solutions with effective renormalization concepts". Polymer. 48 (16): 4883–4899. doi:10.1016/j.polymer.2007.05.080.

Related Research Articles

Condensed matter physics Branch of physics dealing with a property of matter

Condensed matter physics is the field of physics that deals with the macroscopic and microscopic physical properties of matter, especially the solid and liquid phases which arise from electromagnetic forces between atoms. More generally, the subject deals with "condensed" phases of matter: systems of many constituents with strong interactions between them. More exotic condensed phases include the superconducting phase exhibited by certain materials at low temperature, the ferromagnetic and antiferromagnetic phases of spins on crystal lattices of atoms, and the Bose–Einstein condensate found in ultracold atomic systems. Condensed matter physicists seek to understand the behavior of these phases by experiments to measure various material properties, and by applying the physical laws of quantum mechanics, electromagnetism, statistical mechanics, and other theories to develop mathematical models.

In theoretical physics, the term renormalization group (RG) refers to a formal apparatus that allows systematic investigation of the changes of a physical system as viewed at different scales. In particle physics, it reflects the changes in the underlying force laws as the energy scale at which physical processes occur varies, energy/momentum and resolution distance scales being effectively conjugate under the uncertainty principle.

Percolation Filtration of fluids through porous materials

Percolation, in physics, chemistry and materials science, refers to the movement and filtering of fluids through porous materials. It is described by Darcy's law. Broader applications have since been developed that cover connectivity of many systems modeled as lattices or graphs, analogous to connectivity of lattice components in the filtration problem that modulates capacity for percolation.

Lattice gauge theory Theory of quantum gauge fields on a lattice

In physics, lattice gauge theory is the study of gauge theories on a spacetime that has been discretized into a lattice.

Self-organized criticality Concept in physics

Self-organized criticality (SOC) is a property of dynamical systems that have a critical point as an attractor. Their macroscopic behavior thus displays the spatial or temporal scale-invariance characteristic of the critical point of a phase transition, but without the need to tune control parameters to a precise value, because the system, effectively, tunes itself as it evolves towards criticality.

Hagen Kleinert German physicist

Hagen Kleinert is professor of theoretical physics at the Free University of Berlin, Germany , Honorary Doctor at the West University of Timișoara, and at the Kyrgyz-Russian Slavic University in Bishkek. He is also Honorary Member of the Russian Academy of Creative Endeavors. For his contributions to particle and solid state physics he was awarded the Max Born Prize 2008 with Medal. His contribution to the memorial volume celebrating the 100th birthday of Lev Davidovich Landau earned him the Majorana Prize 2008 with Medal. He is married to Dr. Annemarie Kleinert since 1974 with whom he has a son Michael Kleinert.

Critical exponents describe the behavior of physical quantities near continuous phase transitions. It is believed, though not proven, that they are universal, i.e. they do not depend on the details of the physical system, but only on some of its general features. For instance, for ferromagnetic systems, the critical exponents depend only on:

Topological order Type of order at absolute zero

In physics, topological order is a kind of order in the zero-temperature phase of matter. Macroscopically, topological order is defined and described by robust ground state degeneracy and quantized non-Abelian geometric phases of degenerate ground states. Microscopically, topological orders correspond to patterns of long-range quantum entanglement. States with different topological orders cannot change into each other without a phase transition.

Auxiliary-field Monte Carlo is a method that allows the calculation, by use of Monte Carlo techniques, of averages of operators in many-body quantum mechanical or classical problems.

A polymer field theory is a statistical field theory describing the statistical behavior of a neutral or charged polymer system. It can be derived by transforming the partition function from its standard many-dimensional integral representation over the particle degrees of freedom in a functional integral representation over an auxiliary field function, using either the Hubbard–Stratonovich transformation or the delta-functional transformation. Computer simulations based on polymer field theories have been shown to deliver useful results, for example to calculate the structures and properties of polymer solutions, polymer melts and thermoplastics.

A field-theoretic simulation is a numerical strategy to calculate structure and physical properties of a many-particle system within the framework of a statistical field theory, like e.g. a polymer field theory. A convenient possibility is to use Monte Carlo (MC) algorithms, to sample the full partition function integral expressed in field-theoretic representation. The procedure is then called the auxiliary field Monte Carlo method. However, it is well known that MC sampling in conjunction with the basic field-theoretic representation of the partition function integral, directly obtained via the Hubbard-Stratonovich transformation, is impracticable, due to the so-called numerical sign problem. The difficulty is related to the complex and oscillatory nature of the resulting distribution function, which causes a bad statistical convergence of the ensemble averages of the desired structural and thermodynamic quantities. In such cases special analytical and numerical techniques are required to accelerate the statistical convergence of the field-theoretic simulation.

Subir Sachdev is Herchel Smith Professor of Physics at Harvard University specializing in condensed matter. He was elected to the U.S. National Academy of Sciences in 2014, and received the Lars Onsager Prize from the American Physical Society and the Dirac Medal from the ICTP in 2018. He was a co-editor of the Annual Review of Condensed Matter Physics from 2017-2019.

A composite fermion is the topological bound state of an electron and an even number of quantized vortices, sometimes visually pictured as the bound state of an electron and, attached, an even number of magnetic flux quanta. Composite fermions were originally envisioned in the context of the fractional quantum Hall effect, but subsequently took on a life of their own, exhibiting many other consequences and phenomena.

Franz Joachim Wegner is emeritus professor for theoretical physics at the University of Heidelberg.

Yaroslav Blanter Russian physicist

Yaroslav Mikhaylovich Blanter is a Russian physicist, an expert in the field of extractive metallurgy and condensed matter physics. As of 2011, he is the Antoni van Leeuwenhoek professor at the Delft University of Technology.

Jean Zinn-Justin is a French theoretical physicist.

Periodic instantons are finite energy solutions of Euclidean-time field equations which communicate between two turning points in the barrier of a potential and are therefore also known as bounces. Vacuum instantons, normally simply called instantons, are the corresponding zero energy configurations in the limit of infinite Euclidean time. For completeness we add that ``sphalerons´´ are the field configurations at the very top of a potential barrier. Vacuum instantons carry a winding number, the other configurations do not. Periodic instantons werde discovered with the explicit solution of Euclidean-time field equations for double-well potentials and the cosine potential with non-vanishing energy and are explicitly expressible in terms of Jacobian elliptic functions. Periodic instantons describe the oscillations between two endpoints of a potential barrier between two potential wells. The frequency of these oscillations or the tunneling between the two wells is related to the bifurcation or level splitting of the energies of states or wave functions related to the wells on either side of the barrier, i.e. . One can also interpret this energy change as the energy contribution to the well energy on either side originating from the integral describing the overlap of the wave functions on either side in the domain of the barrier.

Amnon Aharony Physicist at Ben Gurion University in Israel

Amnon Aharony is an Israeli Professor (Emeritus) of Physics in the School of Physics and Astronomy at Tel Aviv University, Israel and in the Physics Department of Ben Gurion University of the Negev, Israel. After years of research on statistical physics, his current research focuses on condensed matter theory, especially in mesoscopic physics and spintronics. He is a member of the Israel Academy of Sciences and Humanities, a Foreign Honorary Member of the American Academy of Arts and Sciences and of several other academies. He also received several prizes, including the Rothschild Prize in Physical Sciences, and the Gunnar Randers Research Prize, awarded every other year by the King of Norway.

Christopher John Pethick is a British theoretical physicist, specializing in many-body theory, ultra-cold atomic gases, and the physics of neutron stars and stellar collapse.

Dietrich Belitz is an American theoretical physicist on the faculty of the University of Oregon. He studies statistical mechanics and condensed matter physics.

References