View source for D meson

{{Short description|Particle in physics}}
{{Infobox particle
| name = D meson
| image = 
| caption = 
| num_types = 
| composition = {{plainlist|
*{{SubatomicParticle|D+}}: {{SubatomicParticle|Charm quark}}{{SubatomicParticle|Down antiquark}}
*{{SubatomicParticle|D-}}: {{SubatomicParticle|Down quark}}{{SubatomicParticle|Charm antiquark}}
*{{SubatomicParticle|D0}}: {{SubatomicParticle|Charm quark}}{{SubatomicParticle|Up antiquark}}
*{{SubatomicParticle|AntiD0}}: {{SubatomicParticle|Up quark}}{{SubatomicParticle|Charm antiquark}}
*{{SubatomicParticle|Strange D+}}: {{SubatomicParticle|Charm quark}}{{SubatomicParticle|Strange antiquark}}
*{{SubatomicParticle|Strange D-}}: {{SubatomicParticle|Strange quark}}{{SubatomicParticle|Charm antiquark}}}}
| statistics = [[Bosonic]]
| group = [[Meson]]s
| interaction = [[Strong interaction|Strong]], [[Weak interaction|weak]], [[Electromagnetic interaction|electromagnetic]], [[Gravity|gravitational]]
| antiparticle = {{plainlist|
*{{SubatomicParticle|D+}}: {{SubatomicParticle|D-}}
*{{SubatomicParticle|D0}}: {{SubatomicParticle|antiD0}}
*{{SubatomicParticle|Strange D+}}: {{SubatomicParticle|Strange D-}}}}
| status = 
| theorized = 
| discovered = [[SLAC]] (1976)
| symbol = {{SubatomicParticle|D+}}, {{SubatomicParticle|D-}}, {{SubatomicParticle|D0}}, {{SubatomicParticle|AntiD0}}, {{SubatomicParticle|Strange D+}}, {{SubatomicParticle|Strange D-}}
| mass = {{plainlist|
*{{SubatomicParticle|D+-}}: {{val|1869.62|0.20|ul=MeV/c2}}
*{{SubatomicParticle|D0}},{{SubatomicParticle|AntiD0}}: {{val|1864.84|0.17|u=MeV/c2}}
*{{SubatomicParticle|Strange D+-}}: {{val|1968.47|0.33|ul=MeV/c2}}}}
| mean_lifetime = {{plainlist|
*{{SubatomicParticle|D+-}}: {{val|1.040|0.007|e=-12}}
*{{SubatomicParticle|D0}},{{SubatomicParticle|AntiD0}}: {{val|4.101|0.015|e=-13}}
*{{SubatomicParticle|Strange D+-}}: {{val|5.00|0.07|e=-13}}}}
| decay_particle = 
| electric_charge = {{plainlist|
*{{SubatomicParticle|D+-}},{{SubatomicParticle|Strange D+-}}: ±1 [[Elementary charge|''e'']]
*{{SubatomicParticle|D0}},{{SubatomicParticle|AntiD0}}: 0 ''e''}}
| spin = 0
| strangeness = {{plainlist|
*{{SubatomicParticle|D+-}},{{SubatomicParticle|D0}},{{SubatomicParticle|antiD0}}: 0
*{{SubatomicParticle|Strange D+-}}: {{+-}}1}}
| charm = +1
| isospin = {{plainlist|
*{{SubatomicParticle|D+}},{{SubatomicParticle|antiD0}}: +{{sfrac|1|2}}
*{{SubatomicParticle|D-}},{{SubatomicParticle|D0}}: &minus;{{sfrac|1|2}}
*{{SubatomicParticle|Strange D+-}}: 0}}
| hypercharge = 
| parity = &minus;1
}}

The '''D&nbsp;mesons''' are the lightest particle containing [[charm quark]]s. They are often studied to gain knowledge on the [[weak interaction]].<ref name=autogenerated1>{{cite web |editor=Nave, G. |year=2016 |title=D&nbsp;meson |website=HyperPhysics |department=Department of Physics & Astronomy |place=Atlanta, GA |publisher=[[Georgia State University]] |url=http://hyperphysics.phy-astr.gsu.edu/hbase/particles/dmeson.html}}</ref>  The [[strangeness|strange]] D [[mesons]] (D<sub>s</sub>) were called "'''F&nbsp;mesons'''" prior to 1986.<ref>{{cite journal |first=C.G. |last=Wohl |year=1984 |title=Review of Particle Physics |publisher=[[Particle Data Group]] |journal=[[Reviews of Modern Physics]] |volume=56 |number=2, Part&nbsp;II |doi=10.1103/RevModPhys.56.S1 |url=https://cds.cern.ch/record/153729/files/RevModPhys.56.S1.pdf}}</ref>

==Overview==
The D&nbsp;mesons were discovered in 1976 by the [[Mark I (detector)|Mark&nbsp;I]] detector at the [[Stanford Linear Accelerator Center]].<ref>{{cite web |last=Kudryavtsev |first=Vitaly A. |title=Charmed mesons |series=Physics&nbsp;466 |type=course files |publisher=[[University of Sheffield]] |url=http://www.kudryavtsev.staff.shef.ac.uk/phy466/charmed-mesons_files/charmed-mesons.ppt}}{{dead link|date=September 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

Since the D&nbsp;mesons are the lightest mesons containing a single charm [[quark]] (or antiquark), they must change the charm (anti)quark into an (anti)quark of another type to decay. Such transitions involve a change of the internal [[Charm (quantum number)|charm quantum number]], and can take place only via the [[weak interaction]]. In D&nbsp;mesons, the charm quark preferentially changes into a strange quark via an exchange of a [[W and Z bosons|W&nbsp;particle]], therefore the D&nbsp;meson preferentially decays into [[kaon]]s ({{Subatomic particle|link=yes|Kaon}}) and [[pion]]s ({{Subatomic particle|link=yes|pion}}).<ref name=autogenerated1/>

==List of D mesons==
{| class="wikitable sortable" style="text-align:center;"
|+ D mesons
|-
! class=unsortable | Particle <br/>name
! Particle <br>symbol
! Antiparticle <br>symbol
! class=unsortable | Quark <br/>content<ref name=PDGQuarkmodel>{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title=Quark Model |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/reviews/quarkmodrpp.pdf}}</ref>
! [[Rest mass]] ([[electron volt|MeV]]/[[speed of light|''c'']]<sup>2</sup>)
! width="50" | [[Isospin|I]]
! width="50" | [[Total angular momentum|J]]<sup>[[Parity (physics)|P]]</sup>
! width="50" | [[strangeness|S]]
! width="50" | [[charm (quantum number)|C]]
! width="50" | [[bottomness|B']]
! [[Mean lifetime]] ([[second|s]])
! class=unsortable|Commonly decays to <br>(>5% of decays)
|-
| Charged D&nbsp;meson<ref name="PDGD+">{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title={{Subatomic particle|D+-}} |series=Particle listings |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/listings/s031.pdf}}</ref>
| {{Subatomic particle|D+}}
| {{Subatomic particle|D-}}
| {{Subatomic particle|link=yes|Charm quark}}{{Subatomic particle|link=yes|Down antiquark}}
| {{val|1869.62|0.20}}
| {{sfrac|1|2}}
| 0<sup>&minus;</sup>
| 0
| +1
| 0
| {{val|1.040|0.007|e=-12}}
| <ref>{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title={{Subatomic particle|D+-}} |series=Decay modes |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/listings/s031.pdf}}</ref>
|-
| Neutral D&nbsp;meson<ref name=PDGD0>{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title={{Subatomic particle|D0}} |series=Particle listings |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/listings/s032.pdf}}</ref>
| {{Subatomic particle|D0}}
| {{Subatomic particle|AntiD0}}
| {{Subatomic particle|link=yes|Charm quark}}{{Subatomic particle|link=yes|up antiquark}}
| {{val|1864.84|0.17}}
| {{sfrac|1|2}}
| 0<sup>&minus;</sup>
| 0
| +1
| 0
| {{val|4.101|0.015|e=-13}}
| <ref>{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title={{Subatomic particle|D0}} |series=Decay modes |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/listings/s032.pdf}}</ref>
|-
| Strange D&nbsp;meson<ref name=PDGDs>{{cite web |first1=N. |last1=Nakamura |display-authors=etal |collaboration=Particle Data Group |year=2010 |title={{Subatomic particle|Strange D+-}} |series=Particle listings |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2010/listings/rpp2010-list-Ds-plus-minus.pdf}}</ref>
| {{Subatomic particle|Strange D+}}
| {{Subatomic particle|Strange D-}}
| {{Subatomic particle|link=yes|Charm quark}}{{Subatomic particle|link=yes|strange antiquark}}
| {{val|1968.47|0.33}}
| 0
| 0<sup><span style="color:red">&minus;</span></sup>
| +1
| +1
| 0
| {{sort|-13.1|{{val|5.00|0.07|e=-13}}}}
| <ref>{{cite web |first1=N. |last1=Nakamura |display-authors=etal |collaboration=Particle Data Group |year=2010 |title={{Subatomic particle|Strange D+}} |series=Decay modes |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2010/listings/rpp2010-list-Ds-plus-minus.pdf}}</ref>
|-
| Excited charged D&nbsp;meson<ref name="PDGD*+">{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title={{Subatomic particle|D*+-}} |series=Decay modes |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/listings/m062.pdf}}</ref>
| {{Subatomic particle|D*+}}(2010)
| {{Subatomic particle|D*-}}(2010)
| {{Subatomic particle|link=yes|Charm quark}}{{Subatomic particle|link=yes|Down antiquark}}
| {{val|2010.27|0.17}}
| <span style="color:red">{{sfrac|1|2}}</span>
| <span style="color:red">1</span><sup><span style="color:red">&minus;</span></sup>
| 0
| +1
| 0
| {{val|6.9|1.9|e=-21}}<sup>{{ref|Lifetime|‡}}</sup>
| {{nowrap|{{Subatomic particle|D0}} + {{Subatomic particle|link=yes|Pion+}} or}}<br/>{{nowrap|{{Subatomic particle|D+}} + {{Subatomic particle|link=yes|Pion0}}}}
|-
| Excited neutral D&nbsp;meson<ref name=PDGD*0>{{cite web |first1=C. |last1=Amsler |display-authors=etal |collaboration=Particle Data Group |year=2008 |title={{Subatomic particle|D*0}} (2007) |series=Decay modes |publisher=[[Lawrence Berkeley Laboratory]] |url=http://pdg.lbl.gov/2008/listings/m061.pdf}}</ref>
| {{Subatomic particle|D*0}}(2007)
| {{Subatomic particle|antiD*0}}(2007)
| {{Subatomic particle|link=yes|Charm quark}}{{Subatomic particle|link=yes|up antiquark}}
| {{val|2006.97|0.19}}
| <span style="color:red">{{sfrac|1|2}}</span>
| <span style="color:red">1</span><sup><span style="color:red">&minus;</span></sup>
| 0
| +1
| 0
| >{{val|3.1||e=-22}}<sup>{{ref|Lifetime|‡}}</sup>
| {{nowrap|{{Subatomic particle|D0}} + {{Subatomic particle|link=yes|Pion0}} or}}<br/>{{nowrap|{{Subatomic particle|D0}} + {{Subatomic particle|link=yes|Photon}}}}
|}
‡ {{note|Lifetime}} PDG reports the resonance width <math>~\left(\Gamma\right)~.</math> Here the conversion <math>\; \tau = \frac{\hbar}{\Gamma} \;</math> is given instead.

==CP violation==
In 2019, an analysis by the [[LHCb experiment]] reported the first observation of [[CP violation]] in the decays of the neutral {{Subatomic particle|D0}} meson, with a significance of over five [[standard deviations]].<ref>{{cite journal |collaboration=LHCb collaboration |author1=Aaij, R. |date=29 May 2019 |orig-date=21 March 2019 |title=Observation of CP Violation in Charm Decays |id=1903.08726  |journal=Physical Review Letters |volume=122 |issue=21 |page=211803 |doi=10.1103/PhysRevLett.122.211803  |pmid=31283320 |arxiv=1903.08726|bibcode=2019PhRvL.122u1803A }}</ref> The results of a subsequent data analysis by the same collaboration was presented in 2022, which announced that they found evidence of direct [[CP violation]] in the decay of the {{Subatomic particle|D0}} meson into [[pion]]s.<ref>{{cite journal |collaboration=LHCb collaboration |author1=Aaij, R. |date=29 August 2023 |orig-date=9 September 2022 |title=Measurement of the Time-Integrated CP Asymmetry in D0 -> KK Decays |id=1903.08726  |journal=Physical Review Letters |volume=131 |issue=9 |page=091802 |doi=10.1103/PhysRevLett.131.091802  |pmid=37721849 |arxiv=2209.03179}}</ref>

=={{Subatomic particle|D}}–{{Subatomic particle|AntiD}} oscillations==
In 2021 it was confirmed with a significance of more than seven [[standard deviations]], that the neutral {{Subatomic particle|D0}} meson spontaneously transforms into its own antiparticle and back. This phenomenon is called [[Neutral particle oscillation|flavor oscillation]] and was prior known to exist in the neutral [[K meson]] and [[B meson]].<ref>{{cite journal |collaboration=LHCb collaboration |author1=Aaij, R. |date=14 September 2021 |orig-date=7 June 2021 |title=Observation of the mass difference between neutral charm-meson eigenstates |id=2106.03744 |journal=Physical Review Letters |volume=127 |issue=11 |page=111801 |doi=10.1103/PhysRevLett.127.111801 |pmid=34558945 |arxiv=2106.03744 |bibcode=2021PhRvL.127k1801A |s2cid=235358523 |quote=Published 2021 in ''Physical Review Letters'' '''127''', 111801. Report numbers: LHCb-PAPER-2021-009, CERN-EP-2021-099.}}</ref>

==See also==
{{div col |colwidth=15em}}
* [[List of mesons]]
* [[List of particles]]
* [[Timeline of particle discoveries]]
{{div col end}}

==References==
{{reflist|25em}}

{{particles}}
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[[Category:Mesons]]