Z(4430)

{{Short description|Mesonic resonance discovered by the Belle experiment}}

{{Expert needed|1=Physics|date=December 2022}}

{{Infobox particle

| name = Z(4430)

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| classification = Exotic meson

| composition = {{Subatomic particle|Charm quark|link=yes}}{{Subatomic particle|Charm antiquark|link=yes}}{{Subatomic particle|Down quark|link=yes}}{{Subatomic particle|Up antiquark|link=yes}}

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Z(4430) is a mesonic resonance discovered by the Belle experiment.

{{cite journal

|last1=Choi | first1=S.-K.

|author2=Belle Collaboration

|author2-link=Belle experiment

|title=Observation of a resonance-like structure in the {{Subatomic particle|Pion+-}}Ψ{{prime}} mass distribution in exclusive B→K{{Subatomic particle|Pion+-}}Ψ{{prime}} decays

|year=2008

|doi=10.1103/PhysRevLett.100.142001

| pmid=18518023

|journal=Physical Review Letters

|volume=100

|issue=14

| pages=142001

|arxiv=0708.1790

|bibcode = 2008PhRvL.100n2001C | s2cid=119138620

|display-authors=etal}}{{cite press release

|url=http://www.kek.jp/intra-e/press/2007/BellePress11e.html

|title=Belle Discovers a New Type of Meson

|publisher=KEK

|year=2007

|access-date=2009-06-20

|archive-date=2009-01-22

|archive-url=https://web.archive.org/web/20090122213256/http://www.kek.jp/intra-e/press/2007/BellePress11e.html

|url-status=dead

}} It has a mass of {{val|4430|ul=MeV/c2}}. The resonant nature of the peak has been confirmed by the LHCb experiment with a significance of at least 13.9 σ.{{cite journal |last=LHCb collaboration |author-link=LHCb |arxiv=1404.1903 |title=Observation of the resonant character of the Z(4430)− state |year=2014 |doi=10.1103/PhysRevLett.112.222002 |pmid=24949760 |volume=112 |issue=22 |pages=222002 |journal=Physical Review Letters |bibcode=2014PhRvL.112v2002A|s2cid=904429 }} The particle is charged and is thought to have a quark content of {{Subatomic particle|Charm quark|link=yes}}{{Subatomic particle|Charm antiquark|link=yes}}{{Subatomic particle|Down quark|link=yes}}{{Subatomic particle|Up antiquark|link=yes}}, making it a tetraquark candidate. It has the spin-parity quantum numbers J^P = 1⁺.

The particle joins the X(3872), Zc(3900) and Y(4140) as exotic hadron candidates observed by multiple experiments, although it is the first to be confirmed as a resonance.{{cite web|url=http://home.web.cern.ch/about/updates/2014/04/lhcb-confirms-existence-exotic-hadrons|title=LHCb confirms existence of exotic hadrons|publisher=CERN|author=Cian O'Luanaigh|date=9 April 2014}}{{cite web|url=http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#Z(4430)|title=Unambiguous observation of an exotic particle which cannot be classified within the traditional quark model|date=9 April 2014|publisher=European Organization for Nuclear Research}}