In
particle physics, the
Lund
Lund (, , ) is a city in the southern Swedish provinces of Sweden, province of Scania, across the Øresund, Öresund strait from Copenhagen. The town had 91,940 inhabitants out of a municipal total of 121,510 . It is the seat of Lund Municipali ...
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
Renormalization is a collection of techniques in quantum field theory, the statistical mechanics of fields, and the theory of self-similarity, self-similar geometric structures, that are used to treat infinity, infinities arising in calculated ...
and so form a narrow tube (or string) of
strong color field. Compared to electric or
magnetic field lines, which are spread out because the carrier of the
electromagnetic force, the
photon, does not interact with itself.
String fragmentation is one of the
parton fragmentation models used in the
PYTHIA/Jetset and
UCLA event generators, and explains many features of hadronization quite well. In particular, the model predicts that in addition to the
particle jet
A jet is a narrow cone of hadrons and other particles produced by the hadronization of a quark or gluon in a particle physics or heavy ion experiment. Particles carrying a color charge, such as quarks, cannot exist in free form because of quant ...
s formed along the original paths of two separating
quark
A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly o ...
s, there will be a spray of
hadrons produced between the jets by the string itself—which is precisely what is observed.
This use of "string" is not the same as in
string theory
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interac ...
, in which strings are the fundamental objects of nature rather than collections of field lines.
See also
*
QCD string
References
*
Quantum chromodynamics
Experimental particle physics
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