Standard Model - Citizendia

For the mathematical formulation of the Standard Model of particle physics, see Standard Model (mathematical formulation). For a basic description see the article on the Standard Model.

For the standard model in cryptography, see Standard Model (cryptography). Cryptography (or cryptology; from Greek grc κρυπτός kryptos, "hidden secret" and grc γράφω gráphō, "I write" In Cryptography the standard model is the model of computation in which the adversary is only limited by the amount of time and computational power available

For standard models in mathematical logic, see intended interpretation. Mathematical logic is a subfield of Logic and Mathematics with close connections to Computer science and Philosophical logic. See also Formal interpretation One who constructs a syntactical system usually has in mind from the outset some Interpretation of this

Quantum field theory

Feynman diagram
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The Standard Model of particle physics is a theory that describes three of the four known fundamental interactions between the elementary particles that make up all matter. In quantum field theory (QFT the forces between particles are mediated by other particles Motivation and history When calculating Scattering cross sections in Particle physics, the interaction between particles can be described The history of quantum field theory starts with its creation by Dirac when he attempted to quantize the Electromagnetic field in the late 1920s Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms 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 Matter is commonly defined as being anything that has mass and that takes up space. It unifies the electroweak theory and quantum chromodynamics into a structure denoted by the gauge groups SU(3)×SU(2)×U(1). In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the Gauge theory is a peculiar Quantum field theory where the Lagrangian is invariant under certain transformations It is a quantum field theory which is consistent with both quantum mechanics and special relativity. In quantum field theory (QFT the forces between particles are mediated by other particles Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons Special relativity (SR (also known as the special theory of relativity or STR) is the Physical theory of Measurement in Inertial To date, almost all experimental tests of the three forces described by the Standard Model have agreed with its predictions. However, the Standard Model falls short of being a complete theory of fundamental interactions, primarily because of its lack of inclusion of gravity, the fourth known fundamental interaction, but also because of the eighteen numerical parameters (such as masses and coupling constants) that must be put "by hand" into the theory (rather than being derived from first principles). A theory of everything ( TOE) is a putative Theory of Theoretical physics that fully explains and links together all known physical phenomena Gravitation is a natural Phenomenon by which objects with Mass attract one another Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object In Physics, a coupling constant, usually denoted g, is a number that determines the strength of an Interaction. First Principles is also the title of a work by Herbert Spencer.

1 Historical background
2 Overview
3 Tests and predictions
4 Challenges to the standard model
5 See also
6 Notes
7 References
8 External links

Historical background

The formulation of the unification of the electromagnetic and weak interactions in the Standard Model is due to Steven Weinberg, Abdus Salam and, subsequently, Sheldon Glashow. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature Steven Weinberg (born May 3, 1933) is an American Physicist, and Nobel laureate in Physics for his contributions with Abdus Salam Abdus Salam ( Urdu: محمد عبد السلام) ( January 29, 1926; Jhang Punjab &ndash November 21, Sheldon Lee Glashow (born December 5, 1932) is an American physicist. The unification model was initially proposed by Steven Weinberg in 1967,^[1] and completed integrating it with the proposal by Peter Higgs of spontaneous symmetry breaking^[2]^[3]^[4] which gives origin to the masses of all particles described in the model. Steven Weinberg (born May 3, 1933) is an American Physicist, and Nobel laureate in Physics for his contributions with Abdus Salam Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar. Peter Ware Higgs, FRS, FRSE, (born May 29, 1929) is a British theoretical physicist and an Emeritus professor In Physics, spontaneous symmetry breaking occurs when a system that is symmetric with respect to some Symmetry group goes into a Vacuum state Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object

After the discovery, made at CERN of the existence of neutral weak currents,^[5]^[6]^[7]^[8] mediated by the Z boson, foreseen in the Standard Model, Glashow, Salam, and Weinberg received the Nobel Prize in physics in 1979. The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN The W and Z bosons are the Elementary particles that mediate the Weak force. The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature Year 1979 ( MCMLXXIX) was a Common year starting on Monday (link displays the 1979 Gregorian calendar)

Overview

In physics, the dynamics of both matter and energy in nature is presently best understood in terms of the kinematics and interactions of fundamental particles. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Matter is commonly defined as being anything that has mass and that takes up space. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός Nature, in the broadest sense is equivalent to the natural world, physical universe, material world or material universe. 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 To date, science has managed to reduce the laws which seem to govern the behavior and interaction of all types of matter and energy we are aware of, to a small core of fundamental laws and theories. Science (from the Latin scientia, meaning " Knowledge " or "knowing" is the effort to discover, and increase human understanding A scientific law is a statement that describes the behavior of some particular thing or set of things within the natural world, with an adequately thorough history of successful A major goal of physics is to find the 'common ground' that would unite all of these into one integrated model of everything, in which all the other laws we know of would be special cases, and from which the behavior of all matter and energy can be derived (at least in principle). "Details can be worked out if the situation is simple enough for us to make an approximation, which is almost never, but often we can understand more or less what is happening. " (Feynman's lectures on Physics, Vol 1. 2–7)

The standard model is a grouping of two major theories — quantum electroweak and quantum chromodynamics — which provides an internally consistent theory describing interactions between all experimentally observed particles. The Feynman Lectures on Physics by Richard Feynman, Robert Leighton, and Matthew Sands is perhaps Feynman's most accessible technical work In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the Technically, quantum field theory provides the mathematical framework for the standard model. In quantum field theory (QFT the forces between particles are mediated by other particles Mathematical physics is the scientific discipline concerned with the interface of Mathematics and Physics. The standard model describes each type of particle in terms of a mathematical field. In Physics, a field is a Physical quantity associated to each point of Spacetime. For a technical description of the fields and their interactions, see standard model (mathematical formulation). For a basic description see the article on the Standard Model.

For ease of description, the standard model can be divided into three parts — particles of matter, force mediating particles, and the Higgs boson. The Higgs Boson is a hypothetical massive scalar Elementary particle predicted to exist by the Standard Model of Particle physics

Particles of matter

The matter particles described by the standard model all have an intrinsic property known as 'spin' whose value is determined to be ½, i. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin e. all matter particles are fermions. In Particle physics, fermions are particles which obey Fermi-Dirac statistics; they are named after Enrico Fermi. For this reason, they follow the Pauli exclusion principle in accordance with the spin-statistics theorem, and it is this which causes their 'material' quality. The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925 The spin-statistics theorem in Quantum mechanics relates the spin of a particle to the statistics obeyed by that particle Apart from their antiparticle partners, a total of twelve different types of matter particles are known and accounted for by the standard model. to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. Six of these are classified as quarks (up, down, charm, strange, top and bottom), and the other six as leptons (electron, muon, tau, and their corresponding neutrinos). In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. The up quark is a particle described by the Standard Model theory of Physics. The down quark is a first-generation Quark with a charge of -(1/3 e. The charm Quark is a second-generation quark with an electric charge of +(2/3 e. The strange quark is a second- generation Quark with a charge of &minus(1/3 e and a strangeness of &minus1 The top quark is the third- generation up-type Quark with a charge of +(2/3 e. The bottom quark is a third-generation Quark with a charge of − e. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 The tau lepton (often called the tau, tau particle, or occasionally the tauon; symbol) is a negatively charged Elementary particle with Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost

Organization of Fermions
	Generation 1		Generation 2		Generation 3
Quarks	Up	u	Charm	c	Top	t
Quarks	Down	d	Strange	s	Bottom	b
Leptons	Electron Neutrino	νe	Muon Neutrino	νμ	Tau Neutrino	ντ
Leptons	Electron	e⁻	Muon	μ⁻	Tau	τ⁻

Matter particles (as do mediating particles) also carry various charges which make them susceptible to the fundamental forces, which are in turn mediated as described in the next subsection. In Physics, a charge may refer to one of many different quantities such as the Electric charge in Electromagnetism or the Color charge in In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms

Each quark can carry any one of three color charges (red, green, or blue), enabling them to participate in strong interactions. In Particle physics, color charge is a property of Quarks and Gluons which are related to their Strong interactions in the context of Quantum In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and
The up-type quarks (up, charm, and top quarks) carry an electric charge of +²⁄₃, and the down-type quarks (down, strange, and bottom) carry an electric charge of −¹⁄₃, enabling both types to participate in electromagnetic interactions. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. In Physics, the electromagnetic force is the force that the Electromagnetic field exerts on electrically charged particles
Leptons do not carry any color charge — they are color neutral, preventing them from participating in strong interactions.
The electron-type leptons (the electron, the muon, and the tau lepton) carry an electric charge of −1, enabling them to participate in electromagnetic interactions.
The neutrino-type leptons (the electron neutrino, the muon neutrino and the tau neutrino) carry no electric charge, preventing them from participating in electromagnetic interactions
Both quarks and leptons carry a handful of flavor charges, including the weak isospin, enabling all particles to interact via the weak nuclear interaction. In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their The weak isospin in Particle physics is a quantum number relating to the Weak interaction, and parallels the idea of Isospin under the Strong The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature

Pairs from each group (one up-type quark, one down-type quark, a down-type lepton and its corresponding neutrino) form what is known as a 'generation'. In Particle physics, a generation is a division of the Elementary particles Between generations particles differ only by their Mass. The corresponding particles between each generation are identical to each other, with the exception of their mass and a property known as their flavor. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object

Force-mediating particles

Summary of interactions between particles described by the Standard Model.

Forces in physics are the ways that particles interact and influence each other. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. At a macro level, the electromagnetic force allows particles to interact with one another via magnetic fields, and the force of gravitation allows two particles with mass to attract one another in accordance with Newton's Law of Gravitation. Macroscopic is commonly used to describe physical objects that are measurable and observable by the Naked eye. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges Gravitation is a natural Phenomenon by which objects with Mass attract one another Newton 's law of universal Gravitation is a physical law describing the gravitational attraction between bodies with mass The standard model explains such forces as resulting from matter particles exchanging other particles, known as force-mediating particles. When a force-mediating particle is exchanged, at a macro level the effect is equivalent to a force influencing both of them, and the particle is therefore said to have mediated (i. Macroscopic is commonly used to describe physical objects that are measurable and observable by the Naked eye. e. , been the agent of) that force. Force-mediating particles are believed to be the reason why the forces and interactions between particles observed in the laboratory and in the universe exist.

The known force-mediating particles described by the Standard Model also all have spin (as do matter particles), but in their case, the value of the spin is 1, meaning that all force-mediating particles are bosons. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein As a result, they do not follow the Pauli Exclusion Principle. The Pauli exclusion principle is a quantum mechanical principle formulated by Wolfgang Pauli in 1925 The different types of force mediating particles are described below.

Photons mediate the electromagnetic force between electrically charged particles. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The photon is massless and is well-described by the theory of quantum electrodynamics. Quantum electrodynamics ( QED) is a relativistic Quantum field theory of Electrodynamics.

The W⁺, W⁻, and Z gauge bosons mediate the weak interactions between particles of different flavors (all quarks and leptons). The W and Z bosons are the Elementary particles that mediate the Weak force. The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their They are massive, with the Z being more massive than the W^±. The weak interactions involving the W^± act on exclusively left-handed particles and right-handed antiparticles. Furthermore, the W^± carry an electric charge of +1 and −1 and couple to the electromagnetic interactions. The electrically neutral Z boson interacts with both left-handed particles and antiparticles. These three gauge bosons along with the photons are grouped together which collectively mediate the electroweak interactions. In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the

The eight gluons mediate the strong interactions between color charged particles (the quarks). Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and In Particle physics, color charge is a property of Quarks and Gluons which are related to their Strong interactions in the context of Quantum Gluons are massless. The eightfold multiplicity of gluons is labeled by a combination of color and an anticolor charge (e. g. , Red-anti-Green). ^[9] Because the gluon has an effective color charge, they can interact among themselves. The gluons and their interactions are described by the theory of quantum chromodynamics. Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the

The interactions between all the particles described by the Standard Model are summarized in the illustration immediately above and to the right.

Force Mediating Particles
Electromagnetic Force		Weak Nuclear Force		Strong Nuclear Force
Photon	γ	W⁺, W⁻, and Z Gauge Bosons	W⁺, W⁻, Z	Gluons	g

The Higgs boson

Main article: Higgs boson

The Higgs particle is a hypothetical massive scalar elementary particle predicted by the Standard Model, and the only fundamental particle predicted by that model which has not been directly observed as yet. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The W and Z bosons are the Elementary particles that mediate the Weak force. The W and Z bosons are the Elementary particles that mediate the Weak force. The W and Z bosons are the Elementary particles that mediate the Weak force. Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the The Higgs Boson is a hypothetical massive scalar Elementary particle predicted to exist by the Standard Model of Particle physics For the pseudoscientific "scalar field theory" see " Scalar field theory (pseudoscience " In Theoretical physics, 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 This is partly because it requires an exceptionally large amount of energy to create and observe under laboratory circumstances. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός It has no intrinsic spin, and thus, (like the force-mediating particles, which also have integral spin) is also classified as a boson. In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein

The Higgs boson plays a unique role in the Standard Model, and a key role in explaining the origins of the mass of other elementary particles, in particular the difference between the massless photon and the very heavy W and Z bosons. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The W and Z bosons are the Elementary particles that mediate the Weak force. Elementary particle masses, and the differences between electromagnetism (caused by the photon) and the weak force (caused by the W and Z bosons), are critical to many aspects of the structure of microscopic (and hence macroscopic) matter; thus, if it is proven to exist, the Higgs boson has an enormous effect on the world around us. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature Macroscopic is commonly used to describe physical objects that are measurable and observable by the Naked eye. In electroweak theory it generates the masses of the massive leptons (electron, muon and tau); and also of the quarks. In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 The tau lepton (often called the tau, tau particle, or occasionally the tauon; symbol) is a negatively charged Elementary particle with In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle.

As of 2007, no experiment has directly detected the existence of the Higgs boson, but there is some indirect evidence for it. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. It is hoped that upon the completion of the Large Hadron Collider, experiments conducted at CERN would bring experimental evidence confirming the existence of the particle. The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN

Science, a journal of original scientific research, has reported: ". . . experimenters may have already overlooked a Higgs particle, argues theorist Chien-Peng Yuan of Michigan State University in East Lansing and his colleagues. Michigan State University ( MSU) is a co-educational public Research university in East Lansing, Michigan USA. They considered the simplest possible supersymmetric theory. Ordinarily, theorists assume that the lightest of theory's five Higgses is the one that drags on the W and Z. Those interactions then feed back on Higgs and push its mass above 121 times the mass of the proton, the highest mass searched for at CERN's Large Electron-Positron (LEP) collider, which ran from 1989 to 2000. But it's possible that the lightest Higgs weighs as little as 65 times the mass of a proton and has been missed, Yuan and colleagues argue in a paper to be published in Physical Review Letters`. Physical Review Letters is one of the most prestigious journals in Physics. "^[10]

List of standard model fermions

This table is based in part on data gathered by the Particle Data Group (QuarksPDF (54. The Particle Data Group is an international collaboration of particle Physicists that compiles and reanalyzes published results related to the properties of particles 8 KiB)). A kibibyte (a contraction of ki lo bi nary byte) is a unit of Information or Computer storage, established by the International

**Left-handed fermions in the Standard Model**
Generation 1
Fermion (left-handed)	Symbol	Electric charge	Weak isospin	Weak hypercharge	Color charge *	Mass **
Electron	$e^-\,$	$-1\,$	$-1/2\,$	$-1\,$	$\bold{1}\,$	511 keV
Positron	$e^+\,$	$+1\,$	$0\,$	$+2\,$	$\bold{1}\,$	511 keV
Electron-neutrino	$\nu_e\,$	$0\,$	$+1/2\,$	$-1\,$	$\bold{1}\,$	< 2 eV ****
Up quark	$u\,$	$+2/3\,$	$+1/2\,$	$+1/3\,$	$\bold{3}\,$	~ 3 MeV ***
Up antiquark	$\bar{u}\,$	$-2/3\,$	$0\,$	$-4/3\,$	$\bold{\bar{3}}\,$	~ 3 MeV ***
Down quark	$d\,$	$-1/3\,$	$-1/2\,$	$+1/3\,$	$\bold{3}\,$	~ 6 MeV ***
Down antiquark	$\bar{d}\,$	$+1/3\,$	$0\,$	$+2/3\,$	$\bold{\bar{3}}\,$	~ 6 MeV ***

Generation 2
Fermion (left-handed)	Symbol	Electric charge	Weak isospin	Weak hypercharge	Color charge *	Mass **
Muon	$\mu^-\,$	$-1\,$	$-1/2\,$	$-1\,$	$\bold{1}\,$	106 MeV
Antimuon	$\mu^+\,$	$+1\,$	$0\,$	$+2\,$	$\bold{1}\,$	106 MeV
Muon-neutrino	$\nu_\mu\,$	$0\,$	$+1/2\,$	$-1\,$	$\bold{1}\,$	< 2 eV ****
Charm quark	$c\,$	$+2/3\,$	$+1/2\,$	$+1/3\,$	$\bold{3}\,$	~ 1. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. The weak isospin in Particle physics is a quantum number relating to the Weak interaction, and parallels the idea of Isospin under the Strong The weak hypercharge in Particle physics is a quantum number relating the Electrical charge and the third component of Weak isospin, and is similar In Particle physics, color charge is a property of Quarks and Gluons which are related to their Strong interactions in the context of Quantum Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. 3 GeV
Charm antiquark	$\bar{c}\,$	$-2/3\,$	$0\,$	$-4/3\,$	$\bold{\bar{3}}\,$	~ 1. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. 3 GeV
Strange quark	$s\,$	$-1/3\,$	$-1/2\,$	$+1/3\,$	$\bold{3}\,$	~ 100 MeV
Strange antiquark	$\bar{s}\,$	$+1/3\,$	$0\,$	$+2/3\,$	$\bold{\bar{3}}\,$	~ 100 MeV

Generation 3
Fermion (left-handed)	Symbol	Electric charge	Weak isospin	Weak hypercharge	Color charge *	Mass **
Tau lepton	$\tau^-\,$	$-1\,$	$-1/2\,$	$-1\,$	$\bold{1}\,$	1. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. The tau lepton (often called the tau, tau particle, or occasionally the tauon; symbol) is a negatively charged Elementary particle with 78 GeV
Anti-tau lepton	$\tau^+\,$	$+1\,$	$0\,$	$+2\,$	$\bold{1}\,$	1. The tau lepton (often called the tau, tau particle, or occasionally the tauon; symbol) is a negatively charged Elementary particle with 78 GeV
Tau-neutrino	$\nu_\tau\,$	$0\,$	$+1/2\,$	$-1\,$	$\bold{1}\,$	< 2 eV ****
Top quark	$t\,$	$+2/3\,$	$+1/2\,$	$+1/3\,$	$\bold{3}\,$	171 GeV
Top antiquark	$\bar{t}\,$	$-2/3\,$	$0\,$	$-4/3\,$	$\bold{\bar{3}}\,$	171 GeV
Bottom quark	$b\,$	$-1/3\,$	$-1/2\,$	$+1/3\,$	$\bold{3}\,$	~ 4. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. 2 GeV
Bottom antiquark	$\bar{b}\,$	$+1/3\,$	$0\,$	$+2/3\,$	$\bold{\bar{3}}\,$	~ 4. In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. 2 GeV
Notes: * These are not ordinary abelian charges, which can be added together, but are labels of group representations of Lie groups. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. In the mathematical field of Representation theory, group representations describe abstract groups in terms of Linear transformations of In Mathematics, a Lie group (ˈliː sounds like "Lee" is a group which is also a Differentiable manifold, with the property that the group Mass is really a coupling between a left-handed fermion and a right-handed fermion. For example, the mass of an electron is really a coupling between a left-handed electron and a right-handed electron, which is the antiparticle of a left-handed positron. to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. The positrons or antielectron is the Antiparticle or the Antimatter counterpart of the Electron. Also neutrinos show large mixings in their mass coupling, so it's not accurate to talk about neutrino masses in the flavor basis or to suggest a left-handed electron antineutrino. In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their *** The masses of baryons and hadrons and various cross-sections are the experimentally measured quantities. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object Baryons are the family of Subatomic particles with a Baryon number of 1 In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( Since quarks can't be isolated because of QCD confinement, the quantity here is supposed to be the mass of the quark at the renormalization scale of the QCD scale. Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the Color confinement, often called just confinement, is the Physics phenomenon that Color charged particles (such as Quarks cannot be isolated singularly In Quantum field theory, the Statistical mechanics of fields and the theory of self-similar geometric structures renormalization refers to a collection ****** The Standard Model assumes that neutrinos are massless. However, several contemporary experiments prove that neutrinos oscillate between their flavour states, which could not happen if all were massless. Neutrino oscillation is a quantum mechanical phenomenon predicted by Bruno Pontecorvo whereby a Neutrino created with a specific Lepton In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their ^[11] It is straightforward to extend the model to fit these data but there are many possibilities, so the mass eigenstates are still open. In Mathematics, given a Linear transformation, an of that linear transformation is a nonzero vector which when that transformation is applied to it changes An open problem is a known problem with importance or interest in some scientific area that can be accurately stated and has not yet been solved (no solution for it is known See Neutrino#Mass. Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost

Log plot of masses in the Standard Model.

Tests and predictions

The Standard Model predicted the existence of W and Z bosons, the gluon, the top quark and the charm quark before these particles had been observed. Their predicted properties were experimentally confirmed with good precision.

The Large Electron-Positron Collider at CERN tested various predictions about the decay of Z bosons, and found them confirmed. The European Organization for Nuclear Research (Organisation Européenne pour la Recherche Nucléaire known as CERN

To get an idea of the success of the Standard Model a comparison between the measured and the predicted values of some quantities are shown in the following table:

Quantity	Measured (GeV)	SM prediction (GeV)
Mass of W boson	80. 398±0. 025	80. 3900±0. 0180
Mass of Z boson	91. 1876±0. 0021	91. 1874±0. 0021

Challenges to the standard model

Unsolved problems in physics: Parameters in the Standard Model: What gives rise to the Standard Model of particle physics? Why do its particle masses and coupling constants possess the values we have measured? Does the Higgs boson predicted by the model really exist? Why are there three generations of particles in the Standard Model?

The Standard Model of particle physics has been empirically determined through experiments over the past fifty years. This is a list of some of the major unsolved problems in Physics. In Physics, a coupling constant, usually denoted g, is a number that determines the strength of an Interaction. The Higgs Boson is a hypothetical massive scalar Elementary particle predicted to exist by the Standard Model of Particle physics In Particle physics, a generation is a division of the Elementary particles Between generations particles differ only by their Mass. Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them A central concept in Science and the Scientific method is that all Evidence must be empirical, or empirically based that is dependent on evidence In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or Currently the Standard Model predicts that there is one more particle to be discovered, the Higgs boson. The Higgs Boson is a hypothetical massive scalar Elementary particle predicted to exist by the Standard Model of Particle physics One of the reasons for building the Large Hadron Collider is that the increase in energy is expected to make the Higgs observable. However, as of 2007, there are only indirect experimental indications for the existence of the Higgs boson and it can not be claimed to be found. In scientific inquiry an experiment ( Latin: Ex- periri, "to try out" is a method of investigating particular types of research questions or

There has been a great deal of both theoretical and experimental research exploring whether the Standard Model could be extended into a complete theory of everything. Research is defined as Human activity based on Intellectual application in the investigation of Matter. A theory of everything ( TOE) is a putative Theory of Theoretical physics that fully explains and links together all known physical phenomena This area of research is often described by the term 'Beyond the Standard Model'. In Physics, the Standard Model of Particle physics is currently the best description of all experimental data There are several motivations for this research. First, the Standard Model does not attempt to explain gravity, and it is unknown how to combine quantum field theory which is used for the Standard Model with general relativity which is the best physical model of gravity. Gravitation is a natural Phenomenon by which objects with Mass attract one another In quantum field theory (QFT the forces between particles are mediated by other particles General relativity or the general theory of relativity is the geometric theory of Gravitation published by Albert Einstein in 1916 This means that there is not a good theoretical model for phenomenon such as the early universe.

Another avenue of research is related to the fact that the standard model seems very ad-hoc and inelegant. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles For example, the theory contains many seemingly so unrelated parameters of the theory — 21 in all (18 parameters in the core theory, plus G, c and h; there are believed to be an additional 7 or 8 parameters required for the neutrino masses although neutrino masses are outside the standard model and the details are unclear). The gravitational constant, denoted G, is a Physical constant involved in the calculation of the gravitational attraction between objects with mass The Planck constant (denoted h\ is a Physical constant used to describe the sizes of quanta. Research also focuses on the Hierarchy problem (why the weak scale and Planck scale are so disparate), and attempts to reconcile the emerging Standard Model of Cosmology with the Standard Model of particle physics. In Theoretical physics, a hierarchy problem occurs when the fundamental parameters ( couplings or masses of some Lagrangian are vastly different (usually In Particle physics and Physical cosmology, the Planck scale is an Energy scale around 1 Cosmology (from Greek grc κοσμολογία - grc κόσμος kosmos, "universe" and grc -λογία -logia) is study Many questions relate to the initial conditions that led to the presently observed Universe. In Mathematics, in the field of Differential equations an initial value problem is an Ordinary differential equation together with specified value called The Universe is defined as everything that Physically Exists: the entirety of Space and Time, all forms of Matter, Energy Examples include: Why is there a matter/antimatter asymmetry? Why is the Universe isotropic and homogeneous at large distances?

Notes

^ S. Matter is commonly defined as being anything that has mass and that takes up space. In Particle physics and Quantum chemistry, antimatter is the extension of the concept of the Antiparticle to Matter, where antimatter is composed Asymmetry is the absence of or a violation of a Symmetry. In organisms Due to how cells divide in Organisms asymmetry in organisms is Isotropy is uniformity in all directions Precise definitions depend on the subject area For other uses see Homogeneous. In Physics, homogeneous mixtures are mixtures that have definite consistent composition and properties For a basic description see the article on the Standard Model. The weak interaction (often called the weak force or sometimes the weak nuclear force) is one of the four Fundamental interactions of nature In Physics, Fermi's interaction is an old explanation of the Weak force, proposed by Enrico Fermi. In Particle physics, the electroweak interaction is the unified description of two of the four Fundamental interactions of nature Electromagnetism and the In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i Quantum chromodynamics (abbreviated as QCD is a theory of the Strong interaction ( color force a Fundamental force describing the interactions of the Quark matter or QCD matter (see QCD) refers to any of a number of theorized phases of matter whose degrees of freedom include Quarks and Gluons In Particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics Neutrinos are Elementary particles that travel close to the Speed of light, lack an Electric charge, are able to pass through ordinary matter almost In Physics, the Standard Model of Particle physics is currently the best description of all experimental data The noncommutative standard model is an extension of the Standard Model to include a modified form of General relativity, developed by Alain Connes Weinberg Phys. Rev. Lett. 19 1264-1266 (1967).
^ P. W. Higgs Phys. Lett. 12 132 (1964), Broken Symmetries, Massless Particles and Gauge Fields
^ P. W. Higgs Phys. Rev. Lett. 13 508 (1964), Broken Symmetries and the Masses of Gauge Bosons
^ Peter Higgs: the man behind the boson. Physicsworld. com (2004-07-10). "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Events 48 BC - Battle of Dyrrhachium, Julius Caesar barely avoids a catastrophic defeat to Pompey in Macedonia. Retrieved on 2008-05-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 589 - Reccared summons the Third Council of Toledo 1450 - Jack Cade's Rebellion: Kentishmen
^ F. J. Hasert et al. Phys. Lett. 46B 121 (1973).
^ F. J. Hasert et al. Phys. Lett. 46B 138 (1973).
^ F. J. Hasert et al. Nucl. Phys. B73 1(1974).
^ The discovery of the weak neutral currents. CERN courier (2004-10-04). "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Events 610 - Heraclius arrives by ship from Africa at Constantinople, overthrows Byzantine Emperor Phocas Retrieved on 2008-05-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 589 - Reccared summons the Third Council of Toledo 1450 - Jack Cade's Rebellion: Kentishmen
^ Technically, there are nine such color-anticolor combinations. However there is one color symmetric combination that can be constructed out of a linear superposition of the nine combinations, reducing the count to eight.
^ Higgs Hiding in Plain Sight?. ScienceNOW (2008-01-23). 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 393 - Roman Emperor Theodosius I proclaims his nine year old son Honorius co-emperor Retrieved on 2008-05-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 589 - Reccared summons the Third Council of Toledo 1450 - Jack Cade's Rebellion: Kentishmen
^ Particle Data Group: Neutrino mass, mixing, and flavor change (2006v)

References

Introductory textbooks

Griffiths, David J. The Particle Data Group is an international collaboration of particle Physicists that compiles and reanalyzes published results related to the properties of particles (1987). Introduction to Elementary Particles. Wiley, John & Sons, Inc. ISBN 0-471-60386-4.
D. A. Bromley (2000). Gauge Theory of Weak Interactions. Springer. ISBN 3-540-67672-4.
Gordon L. Kane (1987). Modern Elementary Particle Physics. Perseus Books. ISBN 0-201-11749-5.

Advanced textbooks

Cheng, Ta Pei; Li, Ling Fong. Gauge theory of elementary particle physics. Oxford University Press. ISBN 0-19-851961-3.

— introduction to all aspects of gauge theories and the Standard Model.
Donoghue, J. F. ; Golowich, E. ; Holstein, B. R. . Dynamics of the Standard Model. Cambridge University Press. ISBN 978-0521476522.

— highlights dynamical and phenomenological aspects of the Standard Model.
O'Raifeartaigh, L. . Group structure of gauge theories. Cambridge University Press. ISBN 0-521-34785-8.

— highlights group-theoretical aspects of the Standard Model.

Journal articles

S. F. Novaes, Standard Model: An Introduction, hep-ph/0001283
D. P. Roy, Basic Constituents of Matter and their Interactions — A Progress Report, hep-ph/9912523
Y. Hayato et al. , Search for Proton Decay through p → νK⁺ in a Large Water Cherenkov Detector. Phys. Rev. Lett. 83, 1529 (1999).
Ernest S. Abers and Benjamin W. Lee, Gauge theories. Physics Reports (Elsevier) C9, 1-141 (1973).

External links

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