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String vibrations. In physics, a string is a physical entity postulated in string theory and related subjects. Unlike elementary particles, which are zero-dimensional or point-like by definition, strings are one-dimensional extended entities. Researchers often have an interest in string theories because theories in which the fundamental ...
String theory has been used to construct a variety of models of particle physics going beyond the standard model. Typically, such models are based on the idea of compactification. Starting with the ten- or eleven-dimensional spacetime of string or M-theory, physicists postulate a shape for the extra dimensions.
The Standard Model is the set of rules that describes the interactions of these particles. In the 1980s, a new mathematical model of theoretical physics, called string theory, emerged. It showed how all the different subatomic particles known to science could be constructed by hypothetical one-dimensional "strings", infinitesimal building ...
In particle physics, the Lund string model is a phenomenological model of hadronization. It treats all but the highest- energy gluons as field lines, which are attracted to each other due to the gluon self-interaction and so form a narrow tube (or string) of strong color field .
At low energies, type IIA string theory is described by type IIA supergravity in ten dimensions which is a non-chiral theory (i.e. left–right symmetric) with (1,1) d=10 supersymmetry; the fact that the anomalies in this theory cancel is therefore trivial.
In physics, the Polyakov action is an action of the two-dimensional conformal field theory describing the worldsheet of a string in string theory.It was introduced by Stanley Deser and Bruno Zumino and independently by L. Brink, P. Di Vecchia and P. S. Howe in 1976, [1] [2] and has become associated with Alexander Polyakov after he made use of it in quantizing the string in 1981. [3]
In 1974, together with John H. Schwarz, Scherk realised that string theory was a theory of quantum gravity. In 1978, together with Eugène Cremmer and Bernard Julia , Scherk constructed the Lagrangian and supersymmetry transformations for eleven-dimensional supergravity , [ 3 ] which is one of the foundations of M-theory .
These parameters can be adjusted so that calculations give adequate results. In string theory, this is unnecessary since the behaviour of the strings is presumed to be known to every scale. Fermions: in the bosonic string, a string can be described as an elastic one-dimensional object (i.e. a line) "living" in spacetime. In superstring theory ...