The Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution equations are equations in
QCD
In theoretical physics, quantum chromodynamics (QCD) is the theory of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a ty ...
describing the variation of
parton distribution functions
In particle physics, the parton model is a model of hadrons, such as protons and neutrons, proposed by Richard Feynman. It is useful for interpreting the cascades of radiation (a parton shower) produced from quantum chromodynamics (QCD) processes a ...
with varying energy scales.
Experimentally observed scaling violation in
deep inelastic scattering
Deep inelastic scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons, muons and neutrinos. It provided the first convincing evidence of the reali ...
is important evidence for the correctness of the equations and of QCD in general.
The equations were first published in the western world by
Guido Altarelli
Guido Altarelli (12 July 1941 – 30 September 2015) was an Italian theoretical physicist.
Biography
Altarelli graduated in Physics from the Sapienza University of Rome in 1963 with Raoul Gatto whom he followed to the University of Florence (196 ...
and
Giorgio Parisi
Giorgio Parisi (born 4 August 1948) is an Italian theoretical physicist, whose research has focused on quantum field theory, statistical mechanics and complex systems. His best known contributions are the QCD evolution equations for parton densit ...
in 1977, and so are still sometimes called the Altarelli–Parisi equations. Only later did it become known that an equivalent formula had been published in Russia by in 1977, and by
Vladimir Gribov
Vladimir Naumovich Gribov (Russian Влади́мир Нау́мович Гри́бов; March 25, 1930, LeningradAugust 13, 1997, Budapest) was a prominent Russian theoretical physicist, who worked on high-energy physics, quantum field theory an ...
and
Lev Lipatov
Lev Nikolaevich Lipatov (russian: Лев Никола́евич Липа́тов; 2 May 1940, Leningrad – 4 September 2017, Dubna) was a Russian physicist, well known for his contributions to nuclear physics and particle physics. He has been th ...
in 1972.
[V. N. Gribov, L. N. Lipatov. ''Sov. J. Nucl. Phys.'' 15:438 (1972).]
The DGLAP QCD evolution equations are widely used in global determinations of
parton distributions, like those from the
CTEQ or
NNPDF
NNPDF is the acronym used to identify the parton distribution functions from the NNPDF Collaboration. NNPDF parton densities are
extracted from global fits to data based on a combination of a Monte Carlo method
Monte Carlo methods, or Monte C ...
collaborations.
See also
*
Jet (particle physics)
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 quantum ...
*
HERA
In ancient Greek religion, Hera (; grc-gre, Ἥρα, Hḗrā; grc, Ἥρη, Hḗrē, label=none in Ionic and Homeric Greek) is the goddess of marriage, women and family, and the protector of women during childbirth. In Greek mythology, she ...
*
APFEL (Software)
APFEL is an opensource software able to perform Dokshitzer–Gribov–Lipatov–Altarelli–Parisi (DGLAP) evolution up to next to next to leading order (NNLO) in quantum chromodynamics (QCD) and to leading order (LO) in quantum electrodynamic ...
References
Further reading
External links
* Guido Altarelli (2009
QCD evolution equations for parton densities Scholarpedia, 4(1):7124.
Quantum chromodynamics
{{particle-stub