Basic Principles
The basic principles are:
- Relativity : The S-matrix is a representation of the Poincaré group.
- Unitarity :
- Analyticity : integral relations and singularity conditions
The basic analyticity principles were also called analyticity of the first kind, and they were never fully enumerated, but they include
- Crossing: The amplitudes for antiparticle scattering are the analytic continuation of particle scattering amplitudes.
- Dispersion relations: the values of the S-matrix can be calculated by integrals over internal energy variables of the imaginary part of the same values.
- Causality conditions: the singularities of the S-matrix can only occur in ways that don't allow the future to influence the past (motivated by Kramers Kronig dispersion relation)
- Landau Principle: Any singularity of the S-matrix corresponds to production thresholds of physical particles.
These principles were to replace the notion of microscopic causality in field theory, the idea that field operators exist at each space time point, and that spacelike separated operators commute with one another.
Read more about this topic: S-matrix Theory
Famous quotes containing the words basic and/or principles:
“The gay world that flourished in the half-century between 1890 and the beginning of the Second World War, a highly visible, remarkably complex, and continually changing gay male world, took shape in New York City.... It is not supposed to have existed.”
—George Chauncey, U.S. educator, author. Gay New York: Gender, Urban Culture, and the Making of the Gay Male World, 1890-1940, p. 1, Basic Books (1994)
“[The sceptic] must acknowledge, if he will acknowledge any thing, that all human life must perish, were his principles to prevail. All discourse, all action would immediately cease, and men remain in a total lethargy, till the necessities of nature, unsatisfied, put an end to their miserable existence.”
—David Hume (1711–1776)