Editing Particle physics (section)

=== Composite ===
{{Main|Composite particle}}
[[File:Quark_structure_proton.svg|thumb|A [[proton]] consists of two up quarks and one down quark, linked together by [[gluon]]s. The quarks' color charge are also visible.]]
The [[neutron]]s and [[proton]]s in the [[Atomic nucleus|atomic nuclei]] are [[baryon]]s – the neutron is composed of two down quarks and one up quark, and the proton is composed of two up quarks and one down quark.<ref name="Knowing2">{{cite book |author=M. Munowitz |title=Knowing |publisher=[[Oxford University Press]] |year=2005 |isbn=0195167376 |page=35}}</ref> A baryon is composed of three quarks, and a [[meson]] is composed of two quarks (one normal, one anti). Baryons and mesons are collectively called [[hadron]]s. Quarks inside hadrons are governed by the strong interaction, thus are subjected to [[quantum chromodynamics]] (color charges). The [[Bound state|bounded]] quarks must have their color charge to be neutral, or "white" for analogy with [[Additive color|mixing the primary colors]].<ref>{{cite book |author=B. A. Schumm |url=https://archive.org/details/deepdownthingsbr00schu/page/131 |title=Deep Down Things |publisher=[[Johns Hopkins University Press]] |year=2004 |isbn=978-0-8018-7971-5 |pages=[https://archive.org/details/deepdownthingsbr00schu/page/131 131–132]}}</ref> More [[exotic hadron]]s can have other types, arrangement or number of quarks ([[tetraquark]], [[pentaquark]]).<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>

A normal atom is made from protons, neutrons and electrons.{{Citation needed|date=July 2022}} By modifying the particles inside a normal atom, [[exotic atom]]s can be formed.<ref>§1.8, ''Constituents of Matter: Atoms, Molecules, Nuclei and Particles'', Ludwig Bergmann, Clemens Schaefer, and Wilhelm Raith, Berlin: Walter de Gruyter, 1997, {{ISBN|3-11-013990-1}}.</ref> A simple example would be the [[hydrogen-4.1]], which has one of its electrons replaced with 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}}</ref>