Editing Strange quark (section)

{{Short description|Type of quark}}
{{distinguish|squark}}
{{Infobox Particle
 |bgcolour        =
 |name            =  Strange quark
 |image           =  [[File:Strange quark.svg|Strange quark]]
 |caption         =
 |num_types       =
 |composition     = [[Elementary particle]]
 |statistics      = [[Fermionic]]
 |group           = [[Quark]]
 |generation      = Second
 |interaction = [[Strong interaction|strong]], [[Weak interaction|weak]], [[electromagnetic force]], [[gravity]]
 |particle        =
 |antiparticle    = {{nowrap|Strange antiquark ({{SubatomicParticle|Strange antiquark}})}}
 |theorized       = [[Murray Gell-Mann]] (1964)<br/>[[George Zweig]] (1964)
 |discovered      = 1947 [[Department of Physics and Astronomy, University of Manchester]], 1968 [[SLAC]]
 |symbol          = {{SubatomicParticle|Strange quark}}
 |mass            = {{val|95|+9|-3|ul=MeV/c2}}<ref name="PDG2018">
  {{cite journal
   |author=M. Tanabashi et al. (Particle Data Group)
   |title=Review of Particle Physics
   |year= 2018
   |doi=10.1103/PhysRevD.98.030001
   |volume=98
   |issue=3
   |pages=1–708
   |journal=Physical Review D
   |pmid=10020536
   |url=http://pdglive.lbl.gov/DataBlock.action?node=Q123SM
   |bibcode=2018PhRvD..98c0001T
   |doi-access=free
  |hdl=10044/1/68623
   |hdl-access=free
   }}</ref>
 |decay_time      =
 |decay_particle  = [[Up quark]]
 |electric_charge = −{{sfrac|1|3}}&nbsp;[[Elementary charge|''e'']]
 |color_charge    = Yes
 |spin            = {{sfrac|1|2}}&nbsp;[[reduced Planck constant|''ħ'']]
 |num_spin_states =
 |weak_isospin    = {{nowrap|[[Chirality (physics)|LH]]: −{{sfrac|1|2}}, [[Chirality (physics)|RH]]: 0}}
 |weak_hypercharge= {{nowrap|[[Chirality (physics)|LH]]: {{sfrac|1|3}}, [[Chirality (physics)|RH]]: −{{sfrac|2|3}}}}
}}

The '''strange quark''' or '''s quark''' (from its symbol, s) is the third lightest of all [[quark]]s, a type of [[elementary particle]]. Strange quarks are found in [[subatomic particle]]s called [[hadron]]s. Examples of hadrons containing strange quarks include [[kaon]]s ({{SubatomicParticle|Kaon}}), [[strange D meson]]s ({{SubatomicParticle|Strange D}}), [[Sigma baryon]]s ({{SubatomicParticle|Sigma}}), and other [[strange particle]]s.

According to the [[IUPAP]], the symbol '''s''' is the official name, while "strange" is to be considered only as a mnemonic.<ref>{{cite book |last1=Cohen |first1=Richard E. |url=http://iupap.org/wp-content/uploads/2014/05/A4.pdf |title=Symbols, Units, Nomenclature and Fundamental Constants in Physics |last2=Giacomo |first2=Pierre |publisher=IUPAP |edition=2010 |page=12 |access-date=25 March 2017 |archive-url=https://web.archive.org/web/20150318052346/http://iupap.org/wp-content/uploads/2014/05/A4.pdf |archive-date=18 March 2015 |url-status=dead}}</ref> The name '''sideways''' has also been used because the s quark (but also the other three remaining quarks) has an [[isospin|I{{sub|3}} value]] of 0 while the u ("up") and d ("down") quarks have values of +{{sfrac|1|2}} and −{{sfrac|1|2}} respectively.<ref>{{cite book |last1=McGervey |first1=John D. |title=Introduction to Modern Physics |date=1983 |publisher=Academic Press |location=New York |isbn=978-0-12-483560-3 |page=658 |edition=second |url=https://books.google.com/books?id=2a94GI0-QF0C&q=%22sideways+quark%22&pg=PA658 |access-date=25 March 2017}}</ref>

Along with the [[charm quark]], it is part of the [[generation (physics)|second generation]] of matter. It has an [[electric charge]] of {{sfrac|−|1|3}}&nbsp;[[elementary charge|''e'']] and a [[bare mass]] of {{val|95|+9|-3|ul=MeV/c2}}.<ref name="PDG2018"/> Like all [[quark]]s, the strange quark is an [[elementary particle|elementary]] [[fermion]] with [[Spin (physics)|spin]] [[spin-1/2|{{sfrac|1|2}}]], and experiences all four [[fundamental interaction]]s: [[gravitation]], [[electromagnetism]], [[weak interaction]]s, and [[strong interaction]]s. The [[antiparticle]] of the strange quark is the '''strange antiquark''' (sometimes called ''antistrange quark'' or simply ''antistrange''), which differs from it only in that some of its properties have [[additive inverse|equal magnitude but opposite sign]].

The first [[strange particle]] (a particle containing a strange quark) was discovered by [[George Rochester]] and [[Clifford Butler]] in [[Department of Physics and Astronomy, University of Manchester]] in 1947 ([[kaon]]s), with the existence of the strange quark itself (and that of the [[up quark|up]] and [[down quark]]s) postulated in 1964 by [[Murray Gell-Mann]] and [[George Zweig]] to explain the ''[[Eightfold way (physics)|eightfold way]]'' classification scheme of [[hadron]]s. The first evidence for the existence of quarks came in 1968, in [[deep inelastic scattering]] experiments at the [[Stanford Linear Accelerator Center]]. These experiments confirmed the existence of up and down quarks, and by extension, strange quarks, as they were required to explain the ''eightfold way''.