This article is about subatomic particles in nuclear physics. A subatomic particle is an elementary or composite Particle smaller than an Atom. Nuclear physics is the field of Physics that studies the building blocks and interactions of Atomic nuclei. For the fictional power source used in the Transformers Universes, see Nucleon (Transformers). Fiction is the telling of stories which are not real More specifically fiction is an imaginative form of Narrative, one of the four basic Rhetorical modes. Nucleon is a power source in the Fictional Transformers universe. For the Ford concept car, see Ford Nucleon. The Ford Nucleon was a nuclear-powered Concept car developed by Ford Motor Company in 1958

In physics a nucleon is a collective name for two baryons: the neutron and the proton. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Baryons are the family of Subatomic particles with a Baryon number of 1 This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive They are constituents of the atomic nucleus and until the 1960s were thought to be elementary particles. The nucleus of an Atom is the very dense region consisting of Nucleons ( Protons and Neutrons, at the center of an atom In Particle physics, an elementary particle or fundamental particle is a particle not known to have substructure that is it is not known to be made In those days their interactions (now called internucleon interactions) defined strong interactions. The nuclear force (or nucleon-nucleon interaction or residual strong force) is the force between two or more Nucleons It is responsible for In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and Now they are known to be composite particles, made of quarks and gluons. In Physics, a bound state is a composite of two or more building blocks ( particles or bodies) that behaves as a single object In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the Understanding the nucleons' properties is one of the major goals of quantum chromodynamics, the modern theory of strong interactions. Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the

The proton is the lightest baryon and its stability is a measure of baryon number conservation. Baryons are the family of Subatomic particles with a Baryon number of 1 In Particle physics, the baryon number is an approximate conserved Quantum number of a system The proton's lifetime thus puts strong constraints on speculative theories which try to extend the Standard Model of particle physics. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles The neutron decays into a proton through the weak decay. Radioactive decay is the process in which an unstable Atomic nucleus loses energy by emitting ionizing particles and Radiation. The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature The two are members of an isospin I=1/2 doublet. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the

Contents 1 The proton 2 The neutron 3 Antinucleons 4 Quark model classification 5 Models of the nucleon 6 See also 7 References

The proton

Main article: proton

With spin and parity 1/2⁺, charge +1, and rest mass of 938 MeV, the proton is the nucleus of a hydrogen atom (₁H). The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Physics, a parity transformation (also called parity inversion) is the flip in the sign of one Spatial Coordinate. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 History See also Atomic theory, Atomism The concept that matter is composed of discrete units and cannot be divided into arbitrarily tiny It has a magnetic moment of 2. In Physics, Astronomy, Chemistry, and Electrical engineering, the term magnetic moment of a system (such as a loop of Electric current 79 nuclear magnetons. The nuclear magneton (symbol \mu_\mathrm{N}\! is a Physical constant of Magnetic moment, defined by \mu_\mathrm{N} = The electric dipole moment is consistent with zero; the bound on it is that it is less than 0. In Physics, the electric dipole moment (or electric dipole for short is a measure of the polarity of a system of Electric charges. 54×10^-23 e-cm.

In some speculative grand unified theories it may decay. Grand Unification, grand unified theory, or GUT refers to any of several very similar unified field theories or models in Physics that The half-life for this decay has been limited to be greater than 2. 1×10²⁹ years. The charge radius is measured mainly through elastic electron-proton scattering and is 0. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J 87 fm. For specific decay modes, into antilepton or lepton and a meson, the bound is often better than 10³² years. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their In Particle physics, a meson is a strongly interacting Boson &mdashthat is a Hadron with integer spin. The proton is therefore taken to be a stable particle, and baryon number is assumed to be conserved. In Particle physics, the baryon number is an approximate conserved Quantum number of a system

The neutron

Main article: neutron

The neutron has no charge, has spin and parity of 1/2⁺, and rest mass of 940 MeV. This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Physics, a parity transformation (also called parity inversion) is the flip in the sign of one Spatial Coordinate. The most precise measurements of its decay lifetime are mainly from traps of various kinds and in beams. The lifetime of a free neutron outside the nucleus is 885. A free neutron is a Neutron that exists outside of an Atomic nucleus. 7±0. 8 s (about 15 minutes). It decays weakly through the process

n⁰ → p⁺ + e⁻ + νe

Its magnetic moment is −1. The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature 91 nuclear magnetons. The nuclear magneton (symbol \mu_\mathrm{N}\! is a Physical constant of Magnetic moment, defined by \mu_\mathrm{N} = Both time reversal and parity invariance of the strong interactions implies that the neutron's electric dipole moment must be zero; the current observational bound is that it is less than 6. 3×10⁻²⁴ e-cm. The mean-square charge radius related to the scattering length measured in low energy electron-neutron scattering for the neutron is −0. The scattering length in Quantum mechanics describes low-energy Scattering. 116 fm².

Violation of baryon number conservation may give rise to oscillations between the neutron and antineutron, through processes which change B by two units. In Particle physics, the baryon number is an approximate conserved Quantum number of a system Using free neutrons from nuclear reactors, as well as neutrons bound inside nuclei, the mean time for these transitions is found to be greater than 1. This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled 3×10⁸ s. The much poorer bound, as compared to protons, is related to the difficulty of the observations.

A limit on electric charge non-conservation comes from the observed lack of the decay

n⁰ → p⁺ + νe + νe

The observations which limit the branching fraction of the neutron in this decay channel to less than 8×10⁻²⁷ are all done looking for appropriate decays of nuclei (A→A and Z→Z+1). Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. In Particle physics and Nuclear physics, the branching fraction for a decay is the fraction of particles which decay by an individual Decay mode with respect

Antinucleons

CPT-symmetry puts strong constraints on the relative properties of particles and antiparticles and, therefore, is open to stringent tests. CPT symmetry is a fundamental symmetry of Physical laws under transformations that involve the inversions of charge, parity and to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. For example, the charges of the proton and the antiproton have to be equal. (This equality has been tested to one part in 10⁸). The equality of their masses is also tested to 10^-8. By holding antiprotons in a Penning trap, the equality of the charge to mass ratio of the proton has been tested to 90×10⁻¹². Penning traps are devices for the storage of charged particles using a constant static Magnetic field and a spatially inhomogeneous static Electric field. The magnetic moment of the antiproton has been found with error of 8×10⁻³ nuclear Bohr magnetons, and is found to be equal and opposite to that of the proton. For the neutron-antineutron system, the masses are equal to within 9×10⁻⁵.

Quark model classification

In the quark model with SU(2) flavour, the two nucleons are part of the ground state doublet. In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i Special Unit 2In Mathematics, the special unitary group of degree n, denoted SU( n) is the group of n × n In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their The proton has quark content of uud, and the neutron, udd. In SU(3) flavour, they are part of the ground state octet (8) of spin 1/2 baryons, known as the Eightfold way. Special Unit 2In Mathematics, the special unitary group of degree n, denoted SU( n) is the group of n × n In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin Baryons are the family of Subatomic particles with a Baryon number of 1 In Physics, the Eightfold Way is a term coined by American Physicist Murray Gell-Mann for a theory organizing subatomic Baryons The other members of this octet are the hyperons strange isotriplet Σ^0,±, the Λ and the strange iso-doublet Ξ^0,-. In Particle physics, a hyperon is any Baryon containing a Strange quark, but no Charm quarks or Bottom quarks Properties One can extend this multiplet in SU(4) flavour (with the inclusion of the charm quark) to the ground state 20-plet.

The article on isospin provides an explicit expression for the nucleon wave functions in terms of the quark flavour eigenstates. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the

Models of the nucleon

Although it is known that the nucleon is made from three quarks, as of 2006, it is not known how to solve the equations of motion for quantum chromodynamics. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the Thus, the study of the low-energy properties of the nucleon are performed by means of models. The only first-principles approach available is to attempt to solve the equations of QCD numerically, using lattice QCD. In Physics, lattice quantum chromodynamics (lattice QCD is a theory of Quarks and Gluons formulated on a space-time lattice. This requires complicated algorithms and very powerful supercomputers. A supercomputer is a Computer that is at the frontline of processing capacity particularly speed of calculation (at the time of its introduction However, several analytic models also exist:

The Skyrmion models the nucleon as a topological soliton in a non-linear SU(2) pion field. In Theoretical physics, a skyrmion, conceived by Tony Skyrme, is a mathematical model used to model Baryons (a Subatomic particle) Also see base concepts Topology, Differential equations Quantum theory & Condensed matter physics. Special Unit 2In Mathematics, the special unitary group of degree n, denoted SU( n) is the group of n × n In Particle physics, pion (short for pi meson) is the collective name for three Subatomic particles, and. The topological stability of the Skyrmion is interpreted as the conservation of baryon number, that is, the non-decay of the nucleon. In Particle physics, the baryon number is an approximate conserved Quantum number of a system The local topological winding number density is identified with the local baryon number density of the nucleon. In Physics, a topological quantum number is any quantity in a physical theory that takes on only one of a discrete set of values due to topological considerations In Particle physics, the baryon number is an approximate conserved Quantum number of a system With the pion isospin vector field oriented in the shape of a hedgehog, the model is readily solvable, and is thus sometimes called the hedgehog model. A hedgehog is any of the small spiny Mammals of the Subfamily Erinaceinae and the order Erinaceomorpha. The hedgehog model is able to predict low-energy parameters, such as the nucleon mass, radius and axial coupling constant, to approximately 30% of experimental values.

The MIT bag model confines three non-interacting quarks to a spherical cavity, with the boundary condition that the quark vector current vanish on the boundary. In Mathematics, in the field of Differential equations a boundary value problem is a Differential equation together with a set of additional restraints In special and General relativity, the four-current is the Lorentz covariant Four-vector that replaces the Electromagnetic Current The non-interacting treatment of the quarks is justified by appealing to the idea of asymptotic freedom, whereas the hard boundary condition is justified by quark confinement. In Physics, asymptotic freedom is the property of some gauge theories in which the interaction between the particles such as Quarks, becomes arbitrarily Color confinement, often called just confinement, is the Physics phenomenon that Color charged particles (such as Quarks cannot be isolated singularly Mathematically, the model vaguely resembles that of a radar cavity, with solutions to the Dirac equation standing in for solutions to the Maxwell equations and the vanishing vector current boundary condition standing for the conducting metal walls of the radar cavity. A cavity magnetron is a high-powered Vacuum tube that generates coherent Microwaves They are commonly found in Microwave ovens as well as various In Physics, the Dirac equation is a relativistic quantum mechanical wave equation formulated by British physicist Paul Dirac in 1928 and provides In Classical electromagnetism, Maxwell's equations are a set of four Partial differential equations that describe the properties of the electric If the radius of the bag is set to the radius of the nucleon, the bag model predicts a nucleon mass that is within 30% of the actual mass. An important failure of the basic bag model is its failure to provide a pion-mediated interaction.

The chiral bag model merges the MIT bag model and the Skyrmion model. In this model, a hole is punched out of the middle of the Skyrmion, and replaced with a bag model. The boundary condition is provided by the requirement of continuity of the axial vector current across the bag boundary. Very curiously, the missing part of the topological winding number (the baryon number) of the hole punched into the Skyrmion is exactly made up by the non-zero vacuum expectation value (or spectral asymmetry) of the quark fields inside the bag. In Quantum field theory the vacuum expectation value (also called condensate) of an operator is its average Expected value in the vacuum In Mathematics and Physics, the spectral asymmetry is the asymmetry in the distribution of the Spectrum of Eigenvalues of an Operator As of 2006, this remarkable trade-off between topology and the spectrum of an operator does not have any grounding or explanation in the mathematical theory of Hilbert spaces and their relationship to geometry. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Topology ( Greek topos, "place" and logos, "study" is the branch of Mathematics that studies the properties of In Functional analysis, the concept of the spectrum of an operator is a generalisation of the concept of Eigenvalues for matrices This article assumes some familiarity with Analytic geometry and the concept of a limit. Geometry ( Greek γεωμετρία; geo = earth metria = measure is a part of Mathematics concerned with questions of size shape and relative position Several other properties of the chiral bag are notable: it provides a better fit to the low energy nucleon properties, to within 5-10%, and these are almost completely independent of the chiral bag radius (as long as the radius is less than the nucleon radius). This independence of radius is referred to as the Cheshire Cat principle, after the fading to a smile of Lewis Carroll's Cheshire Cat. Charles Lutwidge Dodgson (ˈdɒdsən (27 January 1832 &ndash 14 January 1898 better known by the Pen name Lewis Carroll (/ˈkærəl/ was an English The Cheshire Cat is a fictional cat appearing in Lewis Carroll 's Alice's Adventures in Wonderland. It is expected that a first-principles solution of the equations of QCD will demonstrate a similar duality of quark-pion descriptions.

See also

• List of particles, hadrons, proton, neutron and quark model
• Standard model of particle physics
• Strong interactions and quantum chromodynamics
• Weak decays and electroweak interactions
• Strange matter

References

• Gerald Edward Brown and A. This is a list of the different types of particles known and hypothesized In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the For the physics concept see Strange matter. Strange Matter is a Children's book series created by Marty M D. Jackson, The Nucleon-Nucleon Interaction, (1976) North-Holland Publishing, Amsterdam ISBN 0-7204-0335-9
• Linas Vepstas, A. D. Jackson, A. S. Goldhaber, Two-phase models of baryons and the chiral Casimir effect, Physics Letters B140 (1984) p. 280-284.
• Linas Vepstas, A. D. Jackson, Justifying the Chiral Bag, Physics Reports, 187 (1990) p. 109-143.
• Particle data group listing on the proton
• Particle data group listing on the neutron

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