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Fix Matter see-also invoke

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Fix Matter see-also invoke

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{{Short description|Study of subatomic particles and forces}}

{{Quantum matter backlink|Particles}}

'''Particle physics''' or '''high-energy physics''' is the study of fundamental particles and forces that constitute [[Book:Quantum_Collection/Matter_(by_scale)#Matter|matter]] and radiation. It studies elementary particles, their interactions, and composite particles such as protons, neutrons, mesons, and other hadrons.

<div style="float:right; border:1px solid #e0d890; background:#fff8cc; padding:6px; margin:0 0 1em 1em; width:460px;">
[[File:Particle Physics.png|450px]]
<div style="font-size:90%;">Overview of particle physics showing the Standard Model, particle interactions, composite particles, antimatter, accelerators, and quantum field concepts.</div>
</div>

== Description ==
Particle physics studies the smallest known building blocks of nature and the forces acting between them. The fundamental particles in the universe are classified in the [[Physics:Quantum Standard Model|Standard Model]] as [[Physics:Quantum fermion|fermions]], which are matter particles, and [[Physics:Quantum boson|bosons]], which are force-carrying particles.

Ordinary matter is made mainly from first-generation fermions: [[Physics:Quantum quark|up and down quarks]], [[Physics:Quantum atoms/electron|electrons]], and electron neutrinos. Up and down quarks form protons and neutrons, while electrons form the outer structure of atoms.

The Standard Model describes three fundamental interactions:

* [[Physics:Quantum electromagnetism|electromagnetism]]
* the weak interaction
* the strong interaction

Gravity is not yet fully incorporated into the Standard Model. Attempts to reconcile gravity with quantum theory include string theory, loop quantum gravity, and other approaches beyond the Standard Model.

== History ==
The idea that matter is made of smaller constituents dates back to ancient atomism.<ref>{{cite web |title=Fundamentals of Physics and Nuclear Physics |url=http://novelresearchinstitute.org/library/PhysNuclphys196p.pdf |url-status=usurped |archive-url=https://web.archive.org/web/20121002214053/http://novelresearchinstitute.org/library/PhysNuclphys196p.pdf |archive-date=2 October 2012 |access-date=21 July 2012}}</ref> In the nineteenth century, John Dalton argued from stoichiometry that each chemical element consisted of a distinct kind of atom.<ref name="MARK I. GROSSMAN">{{cite journal |title=John Dalton and the London Atomists |year=2014 |pmc=4213434 |last1=Grossman |first1=M. I. |journal=Notes and Records of the Royal Society of London |volume=68 |issue=4 |pages=339–356 |doi=10.1098/rsnr.2014.0025 }}</ref>

In the twentieth century, atoms were shown to contain smaller particles such as electrons, protons, and neutrons. Nuclear physics and quantum physics led to the understanding of nuclear fission and fusion. Hans Bethe’s work on the Lamb shift is often regarded as opening the way toward modern particle physics.<ref>{{Cite book |last1=Brown |first1=Gerald Edward |url=https://archive.org/details/hansbethehisphys0000unse/page/161 |title=Hans Bethe and His Physics |last2=Lee |first2=Chang-Hwan |date=2006 |publisher=World Scientific Publishing |isbn=978-981-256-609-6 |location=Singapore |page=161}}</ref>

During the 1950s and 1960s, many new particles were discovered in high-energy collisions. This variety became known as the "particle zoo". The development of the quark model and the Standard Model explained many of these particles as composites of a smaller set of elementary particles.<ref>{{cite book |last1=Weinberg |first1=Steven |title=The quantum theory of fields |date=1995–2000 |publisher=Cambridge University Press |isbn=978-0-521-67053-1 |location=Cambridge}}</ref><ref>{{Cite journal |last=Jaeger |first=Gregg |date=2021 |title=The Elementary Particles of Quantum Fields |journal=Entropy |volume=23 |issue=11 |page=1416 |bibcode=2021Entrp..23.1416J |doi=10.3390/e23111416 |pmc=8623095 |pmid=34828114 |doi-access=free}}</ref>

== Standard Model ==
The [[Physics:Quantum Standard Model|Standard Model]] is the current framework for classifying elementary particles and describing their electromagnetic, weak, and strong interactions. It includes quarks, leptons, gauge bosons, and the Higgs boson.

The gauge bosons include the photon, eight gluons, the W and Z bosons, and the Higgs boson as a scalar boson associated with the Higgs field.<ref name="Baker p 120">{{cite book |last=Baker |first=Joanne |title=50 quantum physics ideas you really need to know |date=2013 |isbn=978-1-78087-911-6 |publication-place=London |pages=120–123 |oclc=857653602}}</ref>

The Standard Model contains fundamental fermions arranged in three generations. It has been tested with great precision, but it is incomplete because it does not include gravity and does not fully explain dark matter, dark energy, or the origin of neutrino masses.<ref name="pdg">{{cite journal |last=Nakamura |first=K. |date=1 July 2010 |title=Review of Particle Physics |journal=Journal of Physics G: Nuclear and Particle Physics |volume=37 |issue=7A |pages=1–708 |bibcode=2010JPhG...37g5021N |doi=10.1088/0954-3899/37/7A/075021 |pmid=10020536 |doi-access=free |hdl-access=free |hdl=10481/34593}}</ref><ref>{{cite web |title=Neutrinos in the Standard Model |url=https://t2k-experiment.org/neutrinos/in-the-standard-model |url-status=live |archive-url=https://web.archive.org/web/20191016010901/https://t2k-experiment.org/neutrinos/in-the-standard-model/ |archive-date=16 October 2019 |access-date=15 October 2019 |publisher=The T2K Collaboration}}</ref>

On 4 July 2012, CERN announced the discovery of a new particle consistent with the Higgs boson.<ref>{{cite journal |last=Mann |first=Adam |date=28 March 2013 |title=Newly Discovered Particle Appears to Be Long-Awaited Higgs Boson |url=https://www.wired.com/wiredscience/2012/07/higgs-boson-discovery/ |url-status=live |journal=Wired Science |archive-url=https://web.archive.org/web/20140211212906/http://www.wired.com/wiredscience/2012/07/higgs-boson-discovery/ |archive-date=11 February 2014 |access-date=6 February 2014}}</ref>

== Elementary particles ==
Elementary particles are particles that, according to current understanding, are not made of smaller constituents.<ref name="braibant">{{cite book |last1=Braibant |first1=S. |url=https://books.google.com/books?id=0Pp-f0G9_9sC&q=61+fundamental+particles&pg=PA314 |title=Particles and Fundamental Interactions: An Introduction to Particle Physics |last2=Giacomelli |first2=G. |last3=Spurio |first3=M. |publisher=[[Springer Science+Business Media|Springer]] |year=2009 |isbn=978-94-007-2463-1 |pages=313–314 |access-date=19 October 2020 |archive-url=https://web.archive.org/web/20210415025723/https://books.google.com/books?id=0Pp-f0G9_9sC&q=61+fundamental+particles&pg=PA314 |archive-date=15 April 2021 |url-status=live}}</ref> They are described by quantum states and by quantum field theory.

Particle physics includes electrons, quarks, neutrinos, photons, muons, gluons, W and Z bosons, the Higgs boson, and many composite particles produced in radioactive decay, scattering, cosmic rays, and accelerator experiments.<ref>{{cite book |last1=Terranova |first1=Francesco |title=A Modern Primer in Particle and Nuclear Physics. |date=2021 |publisher=Oxford Univ. Press |isbn=978-0-19-284524-5}}</ref>

== Quarks and leptons ==
Quarks and leptons are fermions. Ordinary matter is composed almost entirely of first-generation particles: up quarks, down quarks, electrons, and electron neutrinos.<ref name="Povh02">{{cite book |author=Povh |first1=B. |title=Particles and Nuclei: An Introduction to the Physical Concepts |last2=Rith |first2=K. |last3=Scholz |first3=C. |last4=Zetsche |first4=F. |last5=Lavelle |first5=M. |date=2004 |publisher=Springer |isbn=978-3-540-20168-7 |edition=4th |chapter=Part I: Analysis: The building blocks of matter |quote=Ordinary matter is composed entirely of first-generation particles, namely the u and d quarks, plus the electron and its neutrino. |access-date=28 July 2022 |chapter-url=https://books.google.com/books?id=rJe4k8tkq7sC&q=povh+%22building+blocks+of+matter%22&pg=PA9 |archive-url=https://web.archive.org/web/20220422024501/https://books.google.com/books?id=rJe4k8tkq7sC&q=povh+%22building+blocks+of+matter%22&pg=PA9 |archive-date=22 April 2022 |url-status=live}}</ref>

Fermions have half-integer spin and obey the Pauli exclusion principle.<ref>{{cite book |author=Peacock |first=K. A. |url=https://archive.org/details/quantumrevolutio00peac |title=The Quantum Revolution |publisher=[[Greenwood Publishing Group]] |year=2008 |isbn=978-0-313-33448-1 |page=[https://archive.org/details/quantumrevolutio00peac/page/n143 125] |url-access=limited}}</ref>

Quarks have fractional electric charge and color charge.<ref>{{cite book |author=Quigg |first=C. |title=The New Physics for the Twenty-First Century |publisher=[[Cambridge University Press]] |year=2006 |isbn=978-0-521-81600-7 |editor=G. Fraser |page=91 |chapter=Particles and the Standard Model}}</ref><ref name="R. Nave">{{cite web |author=Nave |first=R. |title=The Color Force |url=http://hyperphysics.phy-astr.gsu.edu/hbase/forces/color.html#c2 |url-status=live |archive-url=https://web.archive.org/web/20181007142048/http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/color.html#c2 |archive-date=7 October 2018 |access-date=2009-04-26 |work=[[HyperPhysics]] |publisher=[[Georgia State University]], Department of Physics and Astronomy}}</ref> Because of color confinement, isolated quarks are not observed under ordinary conditions.<ref name="R. Nave"/>

Leptons include the electron, muon, tau, and their associated neutrinos. Leptons have integer electric charge: charged leptons have charge −1, while neutrinos are electrically neutral.<ref>{{Cite book |last1=Serway |first1=Raymond A. |url=https://books.google.com/books?id=ecYWAAAAQBAJ |title=Physics for Scientists and Engineers, Volume 2 |last2=Jewett |first2=John W. |date=2013-01-01 |publisher=Cengage Learning |isbn=978-1-285-62958-2 |language=en}}</ref>

== Bosons ==
Bosons are particles with integer spin. In the Standard Model, gauge bosons mediate fundamental interactions.<ref name="DarkMatter">{{cite book |author=Carroll, Sean |author-link = Sean M. Carroll | title=Guidebook |publisher=The Teaching Company |year=2007 |isbn=978-1-59803-350-2 |series=Dark Matter, Dark Energy: The dark side of the universe |at=Part 2, p. 43 }}</ref>

The photon mediates electromagnetism.<ref>"Role as gauge boson and polarization" §5.1 in {{cite book |last1=Aitchison |first1=I. J. R. |title=Gauge Theories in Particle Physics |last2=Hey |first2=A. J. G. |publisher=[[IOP Publishing]] |year=1993 |isbn=978-0-85274-328-7}}</ref> The W and Z bosons mediate the weak interaction.<ref>{{cite book |first=Peter |last=Watkins |url=https://books.google.com/books?id=J808AAAAIAAJ&pg=PA70 |title=Story of the W and Z |publisher=[[Cambridge University Press]] |year=1986 |isbn=978-0-521-31875-4 |location=Cambridge |page=70 |access-date=28 July 2022 |archive-url=https://web.archive.org/web/20121114055111/http://books.google.co.uk/books?id=J808AAAAIAAJ&pg=PA70 |archive-date=14 November 2012 |url-status=live}}</ref> Gluons mediate the strong interaction and bind quarks into hadrons.<ref name="HyperPhysics">{{cite web |author=Nave |first=C. R. |title=The Color Force |url=http://hyperphysics.phy-astr.gsu.edu/hbase/forces/color.html |url-status=live |archive-url=https://web.archive.org/web/20181007142048/http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/color.html |archive-date=7 October 2018 |access-date=2012-04-02 |work=[[HyperPhysics]] |publisher=[[Georgia State University]], Department of Physics}}</ref>

The Higgs boson is associated with the Higgs mechanism, which gives mass to the W and Z bosons.<ref name="PDG">{{cite web |author1=Bernardi, G. |author2=Carena, M. |author3=Junk, T. |year=2007 |title=Higgs bosons: Theory and searches |url=http://pdg.lbl.gov/2008/reviews/higgs_s055.pdf |url-status=live |archive-url=https://web.archive.org/web/20181003190309/http://pdg.lbl.gov/2008/reviews/higgs_s055.pdf |archive-date=3 October 2018 |access-date=28 July 2022 |series=Review: Hypothetical particles and Concepts |publisher=Particle Data Group}}</ref>

== Composite particles ==
Composite particles are made of smaller constituents. Protons and neutrons are baryons made of three quarks.<ref name="Knowing2">{{cite book |author=Munowitz |first=M. |title=Knowing |publisher=[[Oxford University Press]] |year=2005 |isbn=0-19-516737-6 |page=35}}</ref> A proton contains two up quarks and one down quark, while a neutron contains two down quarks and one up quark.

Baryons and mesons are collectively called hadrons. Mesons contain a quark and an antiquark. More exotic hadrons, such as tetraquarks and pentaquarks, contain other arrangements of quarks.<ref>{{cite journal |last=Close |first=F. E. |year=1988 |title=Gluonic Hadrons |journal=Reports on Progress in Physics |volume=51 |pages=833–882 |bibcode=1988RPPh...51..833C |doi=10.1088/0034-4885/51/6/002 |number=6|s2cid=250819208 }}</ref>

Atoms are made from protons, neutrons, and electrons.<ref>{{Cite book |last1=Kofoed |first1=Melissa |last2=Miller |first2=Shawn |date=July 2024 |title=Introductory Chemistry |url=https://uen.pressbooks.pub/introductorychemistry/}}</ref> Exotic atoms may be formed when one ordinary constituent is replaced by another particle, such as a muon.<ref>{{Cite journal |last1=Fleming |first1=D. G. |last2=Arseneau |first2=D. J. |last3=Sukhorukov |first3=O. |last4=Brewer |first4=J. H. |last5=Mielke |first5=S. L. |last6=Schatz |first6=G. C. |last7=Garrett |first7=B. C. |last8=Peterson |first8=K. A. |last9=Truhlar |first9=D. G. |date=28 Jan 2011 |title=Kinetic Isotope Effects for the Reactions of Muonic Helium and Muonium with H<sub>2</sub> |url=https://www.science.org/doi/abs/10.1126/science.1199421 |journal=Science |volume=331 |issue=6016 |pages=448–450 |doi=10.1126/science.1199421 |pmid=21273484 |bibcode=2011Sci...331..448F |s2cid=206530683|url-access=subscription }}</ref>

== Antiparticles ==
Most particles have corresponding antiparticles with the same mass but opposite charge or opposite quantum numbers. The antiparticle of the electron is the positron. When a particle and its antiparticle meet, they may annihilate into other particles or photons.<ref>{{cite web |title=Antimatter |url=http://www.lbl.gov/abc/Antimatter.html |url-status=live |archive-url=https://web.archive.org/web/20080823180515/http://www.lbl.gov/abc/Antimatter.html |archive-date=23 August 2008 |access-date=3 September 2008 |publisher=[[Lawrence Berkeley National Laboratory]]}}</ref>

Antiparticles carry opposite baryon or lepton number compared with their corresponding matter particles.<ref>{{cite journal |last=Tsan |first=Ung Chan |date=2013 |title=Mass, Matter, Materialization, Mattergenesis and Conservation of Charge |journal=International Journal of Modern Physics E |volume=22 |issue=5 |page=1350027 |bibcode=2013IJMPE..2250027T |doi=10.1142/S0218301313500274 }}</ref>

== Experimental particle physics ==
Experimental particle physics studies particles using radioactive decay, cosmic rays, detectors, and particle accelerators. Important laboratories include CERN, Fermilab, Brookhaven National Laboratory, DESY, KEK, SLAC, and other accelerator centers.

The [[Physics:Quantum Large Hadron Collider|Large Hadron Collider]] at CERN is the world’s most powerful proton collider and was used in the discovery of the Higgs boson.<ref>{{cite web |url=http://info.cern.ch/ |title=Welcome to |publisher=Info.cern.ch |access-date=23 June 2012 |archive-date=5 January 2010 |archive-url=https://web.archive.org/web/20100105103513/http://info.cern.ch/ |url-status=live }}</ref>

Other experiments study neutrino oscillations, heavy-ion collisions, antimatter, rare decays, and possible physics beyond the Standard Model.<ref>{{cite web|url=http://legacy.kek.jp/intra-e/index.html |title=Kek | High Energy Accelerator Research Organization |publisher=Legacy.kek.jp |access-date=23 June 2012 |archive-url=https://web.archive.org/web/20120621201554/http://legacy.kek.jp/intra-e/index.html |archive-date=21 June 2012 }}</ref>

== Theory ==
Theoretical particle physics develops models and mathematical tools to explain experiments and predict new phenomena. It uses quantum mechanics, special relativity, quantum field theory, gauge theory, effective field theory, perturbation theory, and lattice field theory.

Major theoretical directions include:

* precision tests of the Standard Model
* quantum chromodynamics
* neutrino physics
* Higgs physics
* physics beyond the Standard Model
* supersymmetry
* dark matter candidates
* string theory
* quantum gravity

The Standard Model is highly successful but incomplete, motivating searches for new particles and interactions.<ref>{{Cite web |last=Gagnon |first=Pauline |date=March 14, 2014 |title=Standard Model: a beautiful but flawed theory |url=http://www.quantumdiaries.org/2014/03/14/the-standard-model-a-beautiful-but-flawed-theory/ |access-date=September 7, 2023 |website=Quantum Diaries}}</ref><ref>{{Cite web |title=The Standard Model |url=https://home.cern/science/physics/standard-model |access-date=September 7, 2023 |website=CERN}}</ref>

== Practical applications ==
Particle physics has produced many practical technologies. Particle accelerators are used to create medical isotopes, support radiation therapy, and study materials. Detector technologies are used in imaging, security, and industry.

The World Wide Web was developed at CERN, and accelerator and detector research has contributed to superconducting technology, computing, medical imaging, and radiation treatment.<ref>{{cite web |url=http://www.fnal.gov/pub/science/benefits/ |title=Fermilab | Science at Fermilab | Benefits to Society |publisher=Fnal.gov |access-date=23 June 2012 |archive-date=9 June 2012 |archive-url=https://web.archive.org/web/20120609161544/http://www.fnal.gov/pub/science/benefits/ |url-status=live }}</ref>

== Future directions ==
Future particle physics aims to test the Standard Model more precisely and search for new physics. Proposed or planned directions include next-generation colliders, neutrino experiments, dark matter searches, precision Higgs measurements, and underground detectors.

The Future Circular Collider has been proposed as a possible successor to the LHC at CERN.<ref>{{Cite web |title=Muon Colliders Hold a Key to Unraveling New Physics |url=http://www.aps.org/publications/apsnews/202111/muon.cfm |access-date=2023-09-17 |website=www.aps.org |language=en}}</ref>

== Properties ==

* studies fundamental particles and interactions
* based on quantum mechanics and quantum field theory
* classified by the Standard Model
* includes fermions, bosons, antiparticles, and composite particles
* uses accelerators, detectors, and high-energy collisions
* connects atomic physics, nuclear physics, cosmology, and quantum theory

=See also=
{{#invoke:PhysicsQC|tocHeadingAndList|Physics:Quantum basics/See also/Matter}}

=References=
{{reflist|3}}

{{Author|Harold Foppele}}

{{Sourceattribution|Particle physics|1}}

Physics:Quantum particle - Revision history

imported>WikiHarold: Fix Matter see-also invoke

imported>WikiHarold: Fix Matter see-also invoke