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The S-matrix is closely related to the transition probability amplitude in quantum mechanics and to cross sections of various interactions; the elements (individual numerical entries) in the S-matrix are known as scattering amplitudes. Poles of the S-matrix in the complex-energy plane are identified with bound states, virtual states or resonances.
The Scattering transfer parameters or T-parameters of a 2-port network are expressed by the T-parameter matrix and are closely related to the corresponding S-parameter matrix. However, unlike S parameters, there is no simple physical means to measure the T parameters in a system, sometimes referred to as Youla waves.
In S-matrix theory, the S-matrix relates the infinite past to the infinite future in one step, without being decomposable into intermediate steps corresponding to time-slices. This program was very influential in the 1960s, because it was a plausible substitute for quantum field theory , which was plagued with the zero interaction phenomenon at ...
In quantum physics, the scattering amplitude is the probability amplitude of the outgoing spherical wave relative to the incoming plane wave in a stationary-state scattering process. [1] At large distances from the centrally symmetric scattering center, the plane wave is described by the wavefunction [ 2 ]
The transition amplitude is then given as the matrix element of the S-matrix between the initial and final states of the quantum system. Feynman used Ernst Stueckelberg's interpretation of the positron as if it were an electron moving backward in time. [3] Thus, antiparticles are represented as moving backward along the time axis in Feynman ...
In quantum field theory, correlation functions, often referred to as correlators or Green's functions, are vacuum expectation values of time-ordered products of field operators. They are a key object of study in quantum field theory where they can be used to calculate various observables such as S-matrix elements.
The S-matrix describes the amplitude for a process with an initial state evolving into a final state .If the initial and final states consist of two clusters, with and close to each other but far from the pair and , then the cluster decomposition property requires the S-matrix to factorize
Crossing states that the same formula that determines the S-matrix elements and scattering amplitudes for particle to scatter with and produce particle and will also give the scattering amplitude for + ¯ + to go into , or for ¯ to scatter with to produce + ¯. The only difference is that the value of the energy is negative for the antiparticle.