Pomeron
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physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, the pomeron is a
Regge trajectory Regge may refer to * Tullio Regge (1931-2014), Italian physicist, developer of Regge calculus and Regge theory * Regge calculus, formalism for producing simplicial approximations of spacetimes * Regge theory, study of the analytic properties of s ...
— a family of particles with increasing spin — postulated in 1961 to explain the slowly rising
cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **Abs ...
of
hadron In particle physics, a hadron (; grc, ἁδρός, hadrós; "stout, thick") is a composite subatomic particle made of two or more quarks held together by the strong interaction. They are analogous to molecules that are held together by the ele ...
ic collisions at high energies. It is named after
Isaak Pomeranchuk Isaak Yakovlevich Pomeranchuk (russian: Исаа́к Я́ковлевич Померанчу́к (Polish spelling: Isaak Jakowliewicz Pomieranczuk); 20 May 1913, Warsaw, Russian Empire – 14 December 1966, Moscow, USSR) was a Soviet Union, Sov ...
.


Overview

While other trajectories lead to falling cross sections, the pomeron can lead to logarithmically rising cross sections — which, experimentally, are approximately constant ones. The identification of the pomeron and the prediction of its properties was a major success of the
Regge theory Regge may refer to * Tullio Regge (1931-2014), Italian physicist, developer of Regge calculus and Regge theory * Regge calculus, formalism for producing simplicial approximations of spacetimes * Regge theory, study of the analytic properties of ...
of
strong interaction The strong interaction or strong force is a fundamental interaction that confines quarks into proton, neutron, and other hadron particles. The strong interaction also binds neutrons and protons to create atomic nuclei, where it is called the n ...
phenomenology. In later years, a BFKL pomeron was derived in further kinematic regimes from perturbative calculations 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 ...
, but its relationship to the pomeron seen in soft high energy scattering is still not fully understood. One consequence of the pomeron hypothesis is that the cross sections of proton–proton and proton–antiproton scattering should be equal at high enough energies. This was demonstrated by the Soviet physicist
Isaak Pomeranchuk Isaak Yakovlevich Pomeranchuk (russian: Исаа́к Я́ковлевич Померанчу́к (Polish spelling: Isaak Jakowliewicz Pomieranczuk); 20 May 1913, Warsaw, Russian Empire – 14 December 1966, Moscow, USSR) was a Soviet Union, Sov ...
by
analytic continuation In complex analysis, a branch of mathematics, analytic continuation is a technique to extend the domain of definition of a given analytic function. Analytic continuation often succeeds in defining further values of a function, for example in a new ...
assuming only that the cross sections do not fall. The pomeron itself was introduced 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 it incorporated this theorem into
Regge theory Regge may refer to * Tullio Regge (1931-2014), Italian physicist, developer of Regge calculus and Regge theory * Regge calculus, formalism for producing simplicial approximations of spacetimes * Regge theory, study of the analytic properties of ...
. Geoffrey Chew and
Steven Frautschi Steven C. Frautschi (; born December 6, 1933) is an American theoretical physicist, currently professor of physics emeritus at the California Institute of Technology (Caltech). He is known principally for his contributions to the bootstrap theory ...
introduced the pomeron in the West. The modern interpretation of
Pomeranchuk's theorem Pomeranchuk's theorem, named after Soviet physicist Isaak Pomeranchuk, states that difference of cross sections of interactions of elementary particles \kappa_1+\kappa_2 and \kappa_1+\bar (i. e. particle with particle \kappa_2, and with its antipa ...
is that the pomeron has no conserved charges—the particles on this trajectory have the
quantum number In quantum physics and chemistry, quantum numbers describe values of conserved quantities in the dynamics of a quantum system. Quantum numbers correspond to eigenvalues of operators that commute with the Hamiltonian—quantities that can be kno ...
s of the
vacuum A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
. The pomeron was well accepted in the 1960s despite the fact that the measured cross sections of proton–proton and proton–antiproton scattering at the energies then available were unequal. The pomeron carries no charges. The absence of electric charge implies that pomeron exchange does not lead to the usual shower of Cherenkov radiation, while the absence of
color charge Color charge is a property of quarks and gluons that is related to the particles' strong interactions in the theory of quantum chromodynamics (QCD). The "color charge" of quarks and gluons is completely unrelated to the everyday meanings of ...
implies that such events do not radiate
pion In particle physics, a pion (or a pi meson, denoted with the Greek letter pi: ) is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the lightest mesons and, more gene ...
s. This is in accord with experimental observation. In high energy proton–proton and proton–antiproton collisions in which it is believed that pomerons have been exchanged, a rapidity gap is often observed: This is a large angular region in which no outgoing particles are detected.


Odderon

The odderon, the counterpart of the pomeron that carries odd
charge parity In physics, the C parity or charge parity is a multiplicative quantum number of some particles that describes their behavior under the symmetry operation of charge conjugation. Charge conjugation changes the sign of all quantum charges (that is, a ...
, was introduced in 1973 by Leszek Łukaszuk and
Basarab Nicolescu Basarab Nicolescu (born March 25, 1942, Ploieşti, Romania) is an honorary theoretical physicist at the Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Nucléaire et de Hautes Énergies, Université Pierre et Marie ...
. Odderons exist 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 ...
as a compound state of three reggeized gluons. Potentially theorized in 2015. It was potentially observed only in 2017 by the TOTEM experiment at the
LHC The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundre ...
. This observation was later confirmed in a joint analysis with the
DØ experiment The DØ experiment (sometimes written D0 experiment, or DZero experiment) was a worldwide collaboration of scientists conducting research on the fundamental nature of matter. DØ was one of two major experiments (the other was the CDF experim ...
at the
Tevatron The Tevatron was a circular particle accelerator (active until 2011) in the United States, at the Fermilab, Fermi National Accelerator Laboratory (also known as ''Fermilab''), east of Batavia, Illinois, and is the second highest energy particle ...
and appeared in the media as the particle's discovery in March 2021.


String theory

In early particle physics, the 'pomeron sector' was what is now called the '
closed string 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 h ...
sector' while what was called the ' reggeon sector' is now the ' open string theory'.


See also

*
Giuseppe Cocconi Giuseppe Cocconi (1914–2008) was an Italian physicist who was director of the Proton Synchrotron at CERN in Geneva. He is known for his work in particle physics and for his involvement with SETI where he wrote, " e probability of success is d ...
* Tamás Csörgő


References


Further reading

* *


External links


Pomerons at Fermilab
* {{Authority control Subatomic particles Quantum chromodynamics Hadrons Hypothetical particles