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A pentaquark is a subatomic particle consisting of a group of five quarks (compared to three quarks in normal baryons and two in mesons), or more specifically four quarks and one anti-quark. Hence it has baryon number 1. It has therefore been assigned a new particle classification, called an exotic baryon. Several experiments have shown that a pentaquark exists with a mass of about 1540 MeV.

The existence of pentaquarks was originally hypothesized by Maxim Polyakov , Dmitri Diakonov , and Victor Petrov at the Petersburg Nuclear Physics Institute in Russia in 1997, but their theory was met with skepticism.

The existence of pentaquarks was proven in July 2003 by experiments run by Takashi Nakano of Osaka University, Japan, and by Ken Hicks at the Thomas Jefferson National Accelerator Facility {Jefferson Lab} in Newport News, Virginia. Their experiments caused a high-energy gamma rayThis article is about electromagnatic radiation. For the power metal band, see Gamma Ray (band Gamma rays (often denoted by the Greek letter gamma, γ) are an energetic form of electromagnetic radiation (see Electromagnetic spectrum) produced by radi to interact with a neutronNeutron Classification Subatomic particle Fermion Hadron Baryon Nucleon Neutron Properties Mass: 940 MeV/ c 2 Electric Charge: 0 C Spin: 1/2 In physics, the neutron is a subatomic particle with no net electric charge and a mass of 940 MeV/ c 2 ( kg; very, creating a meson and a pentaquark. However, the pentaquark only survived for about 10-20 secondsTo help compare orders of magnitude of different times this page lists times between 10-20 seconds and 10-19 seconds (10 zeptoseconds and 100 zeptoseconds) See also times of other orders of magnitude. shorter times about 17 zs the approximate period of el before decayRadioactivity Radioactive decay is the process by which radionuclides decay, emitting ionizing radiation. Such nuclear reactions involve a change in the composition of the nucleus, in contrast to chemical reactions which involve only an exchange or sharining into a meson and a neutron.

The first pentaquark discovered, with the symbol Θ+, is composed of two up quarks, two down quarks and an anti-strange quark ().


1 See also

List of particlesElementary particles An elementary particle is a particle with no measurable internal structure, that is, it is not a composite of other particles. In a quantum field theory, these are the particles which are created and annihilated by the field operators

Particles in Physics - Composite particles

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Molecules | Atoms | Atomic nuclei | Hadrons | Baryons | Mesons | Exotic baryons | Exotic mesons | Tetraquarks | Pentaquarks | Hyperons | Hybrids

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PentaquarkA pentaquark is a subatomic particle consisting of a group of five quarks (compared to three quarks in normal baryons and two in mesons), or more specifically four quarks and one anti-quark. Hence it has baryon number 1. It has therefore been assigned a n  


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