{{Short description|Subatomic particle}}

! class=unsortable|Particle! Symbol! Makeup! Rest mass (MeV/c2)! Isospin, I! Spin, parity, J P! Q! S! C! B! Mean lifetime (s)! class=unsortable|Decays to| XiJOURNAL

, W.-M., Yao
, etal
, Particle Data Group
, 2006
, Particle listings â€“ Xi{{sup, 0,
|journal=Journal of Physics G
|volume=33 |issue=1 |pages=1â€“1232]
|bibcode=2006JPhG...33....1Y |arxiv=astro-ph/0601168
|doi=10.1088/0954-3899/33/1/001
|url=http://pdg.lbl.gov/2007/listings/s023.pdf

}}| XiJOURNAL

, W.-M., Yao
, etal
, Particle Data Group
, 2006
, Particle listings â€“ Xi{{sup, −,
|url=http://pdg.lbl.gov/2007/listings/s022.pdf
|journal=Journal of Physics G
|volume=33 |issue=1 |pages=1â€“1232
|bibcode=2006JPhG...33....1Y |doi=10.1088/0954-3899/33/1/001
|arxiv=astro-ph/0601168

}}| Xi resonanceJOURNAL

, W.-M., Yao
, etal
, Particle Data Group
, 2006
, Particle Listings â€“ Xi(1530)
,weblink
, Journal of Physics G
, 33, 1, 1â€“1232
, 10.1088/0954-3899/33/1/001
, astro-ph/0601168, 2006JPhG...33....1Y

, | Xi resonance| charmed XiJOURNAL

, W.-M., Yao
, etal
, Particle Data Group
, 2006
, Particle listings â€“ Charmed baryons
, Journal of Physics G
,weblink
, 33, 1, 1â€“1232
, astro-ph/0601168
, 2006JPhG...33....1Y
, 10.1088/0954-3899/33/1/001

, | charmed Xi| charmed Xi resonance| charmed Xi resonance<{{val| bottom XiJOURNAL

, W.-M., Yao
, etal
, Particle Data Group
, Particle listings â€“ Xib
, Journal of Physics G
, 2006
, 33, 1, 1â€“1232
, astro-ph/0601168, 2006JPhG...33....1Y
, 10.1088/0954-3899/33/1/001
,weblink

, | bottom Xi orCascade B|||

factoids

name

Xi baryon| num_types = 2

: {{SubatomicParticle|Up quark{edih}{{SubatomicParticle|Strange quark}}{{SubatomicParticle|Strange quark}}

{{SubatomicParticle|Xi-}}: {{SubatomicParticle|Down quark}}{{SubatomicParticle|Strange quark}}{{SubatomicParticle|Strange quark}}}}| statistics = Fermionic| group = Baryons

Strong interaction>Strong, Weak interaction

{{nowrap|{{SubatomicParticle|Xi0{edih}: {{val|1314.86|0.20|ul=MeV/c2}}JOURNAL, Review of Particle Physics, Zyla, P. A., Barnett, R. M., 1, Particle Data Group, Progress of Theoretical and Experimental Physics, 2020, 083C01, 2020, 8, 10.1093/ptep/ptaa104, free, 11585/772320, free, }}
{{nowrap|{{SubatomicParticle|Xi-}}: {{val|1321.71|0.07|u=MeV/c2}}}}}}| mean_lifetime = | width = | decay_particle = | electric_charge = | charge_radius = | electric_dipole_moment = | electric_polarizability = | magnetic_moment = | magnetic_polarizability = | color_charge =

1|2}}| num_spin_states = | baryon_number = | strangeness = -2| charm = | bottomness = | topness =

1|2}}| weak_isospin = | weak_isospin_3 = | hypercharge = | weak_hypercharge = | chirality = | B-L =| X_charge =| parity = | g_parity = | c_parity = | r_parity = | condensed_symmetries =}}The Xi baryons or cascade particles are a family of subatomic hadron particles which have the symbol {{math|Îž}} and may have an electric charge ({{mvar|Q}}) of +2 {{mvar|e}}, +1 {{mvar|e}}, 0, or âˆ’1 {{mvar|e}}, where {{mvar|e}} is the elementary charge.Like all conventional baryons, {{math|Îž}} particles contain three quarks. {{math|Îž}} baryons, in particular, contain either one up or one down quark and two other, more massive quarks. The two more massive quarks are any two of strange, charm, or bottom (doubles allowed). For notation, the assumption is that the two heavy quarks in the {{math|Îž}} are both strange; subscripts "c" and "b" are added for each even heavier charm or bottom quark that replaces one of the two presumed strange quarks.They are historically called the cascade particles because of their unstable state; they are typically observed to decay rapidly into lighter particles, through a chain of decays (cascading decays).WEB

, R., Nave
, The Xi Baryon
, HyperPhysics
,weblink
, 4 April 2013

The first discovery of a charged Xi baryon was in cosmic ray experiments by the Manchester group in 1952.

JOURNAL

, R., Armenteros
, etal
, Manchester group
, 1952
, The properties of charged V-particles
, Philosophical Magazine
, 43, 341, 597
, 10.1080/14786440608520216

The first discovery of the neutral Xi particle was at Lawrence Berkeley Laboratory in 1959.

JOURNAL

, L.W., Alvarez
, etal
, 1959
, Neutral Cascade Hyperon Event
, Physical Review Letters
, 2, 5, 215
, 1959PhRvL...2..215A, 10.1103/PhysRevLett.2.215
,weblink

It was also observed as a daughter product from the decay of the omega baryon ({{math|{{SubatomicParticle|Omega-}}}}) observed at Brookhaven National Laboratory in 1964. The Xi spectrum is important to nonperturbative quantum chromodynamics (QCD), such as lattice QCD.{{why|date=December 2016}}

History

The {{math|{{SubatomicParticle|Bottom Xi-}}}} particle is also known as the cascade B particle and contains quarks from all three families. It was discovered by DÃ˜ and CDF experiments at Fermilab. The discovery was announced on 12 June 2007. It was the first known particle made of quarks from all three quark generations â€“ namely, a down quark, a strange quark, and a bottom quark. The DÃ˜ and CDF collaborations reported the consistent masses of the new state. The Particle Data Group world average mass is {{val|5.7924|0.0030|u=GeV/c2}}.For notation, the assumption is that the two heavy quarks are both strange, denoted by a simple {{math|Îž}} ; a subscript "c" is added for each constituent charm quark, and a "b" for each bottom quark. Hence {{math|Îž}}{{sub|c}}, {{math|Îž}}{{sub|b}}, {{math|Îž}}{{sub|cc}}, {{math|Îž}}{{sub|cb}}, etc.Unless specified, the non-up/down quark content of Xi baryons is strange (i.e. there is one up or down quark and two strange quarks). However a {{math|{{SubatomicParticle|Bottom Xi0}}}} contains one up, one strange, and one bottom quark, while a {{math|{{SubatomicParticle|Double bottom xi0}}}} contains one up and two bottom quarks.In 2012, the CMS experiment at the Large Hadron Collider detected a {{math|{{SubatomicParticle|bottom xi*0}}}} baryon (reported mass {{val|5945|2.8|u=MeV/c2}}).WEB

, C., Simpson
, 28 April 2013
, New particle discovered with 'Higgs boson' machine
, The Atlantic Wire
,weblink
, 2013-04-04

, JOURNAL

, S., Chatrchyan
, etal
, Compact Muon Solenoid, CMS Collaboration
, 2012
, Observation of a new Îžb baryon
, Physical Review Letters
, 108, 25, 252002
, 1204.5955, 2012PhRvL.108y2002C, 23004588
, 10.1103/PhysRevLett.108.252002, 119204847
,
(Here,"*" indicates a baryon decuplet.) The LHCb experiment at CERN discovered two new Xi baryons in 2014: {{math|{{Subatomic particle|bottom xi'-}}}} and {{math|{{Subatomic particle|bottom xi*-}}}}.

PRESS RELEASE

, LHCb experiment observes two new baryon particles never seen before
, 19 November 2014
, CERN
, Bern, CH
,weblink

, In 2017, the LHCb researchers reported yet another Xi baryon: the double charmed {{math| {{SubatomicParticle|Double charmed Xi++}} }} baryon, consisting of two heavy charm quarks and one up quark. The mass of {{math|{{SubatomicParticle|Double charmed Xi++}}}} is about 3.8 times that of a proton.PRESS RELEASE

, The LHCb experiment is charmed to announce observation of a new particle with two heavy quarks
, 2017-07-06
, CERN
,weblink
, 2017-07-06

, NEWS

, Chang, Kenneth
, 2017-07-06
, CERN physicists find a particle with a double dose of charm
, The New York Times
, en-US, 0362-4331
,weblink
, 2017-07-08

List of Xi baryons

Isospin and spin values in parentheses have not been firmly established by experiments, but are predicted by the quark model and are consistent with the measurements.{| class="wikitable sortable"|+ Xi baryonsJOURNAL

, V., Abazov
, etal
, D0 experiment, D0 Collaboration
, 2007
, Direct observation of the strange b baryon {{math, {{SubatomicParticle, Bottom Xi-, }}
|journal=Physical Review Letters
|volume=99 |issue=5 |pages=52001
|arxiv=0706.1690 |bibcode=2007PhRvL..99e2001A
|doi=10.1103/PhysRevLett.99.052001
|pmid=17930744 |hdl=10211.3/194385 |s2cid=11568965

}}PRESS RELEASE

, Fermilab physicists discover "triple-scoop" baryon
, 13 June 2007
, Fermilab
,weblink
, 2007-06-14

, PRESS RELEASE

, Back-to-back b baryons in Batavia
, 25 June 2007
, Fermilab
,weblink
, 2007-06-25

, JOURNAL

, T., Aaltonen
, etal
, Collider Detector at Fermilab, CDF Collaboration
, 2007
, Observation and mass measurement of the baryon Îž{{su, b, −,
|journal=Physical Review Letters
|volume=99 |issue=5 |page=52002
|arxiv=0707.0589 |bibcode=2007PhRvL..99e2002A |s2cid=45025038
|pmid=17930745 |hdl=10261/8530 |doi=10.1103/PhysRevLett.99.052002

}}

{{math

Xi0}} }}

{{math

link=yes

link=yes|Strange quark}} }}

{{val

0.20}}

{{sfrac

2}}

{{sfrac

2}}(+)

âˆ’2

{{val

0.09|e=-10}}

{{math

{{SubatomicParticle

Lambda0}} + {{SubatomicParticle

Pion0}}}} }}

{{math

Xi-}} }}

{{math

link=yes

link=yes|Strange quark}} }}

{{val

0.07}}

{{sfrac

2}}

{{sfrac

2}}(+)

âˆ’1

âˆ’2

{{val

0.015|e=-10}}

{{math

{{SubatomicParticle

Lambda0}} + {{SubatomicParticle

Pion-}} }} }}

{{math

Xi0}}}}(1530)

{{math

link=yes

link=yes|Strange quark}} }}

{{val

0.32}}

{{sfrac

2}}

{{sfrac

2}}+

âˆ’2

{{val

0.4

name="decaywidth"

Î“}}) was reported for this species. Here the conversion {{mvar

Ä§|Î“}} }} is given instead.}}

{{math

{{SubatomicParticle

Xi}} + {{SubatomicParticle

Pion}} }} }}

{{math

Xi-}}}}(1530)

{{math

link=yes

link=yes|Strange quark}} }}

{{val

0.6}}

{{sfrac

2}}

{{sfrac

2}}+

âˆ’1

âˆ’2

{{val

1.6

e=-23}}{{efn|name="decaywidth"}}

{{math

{{SubatomicParticle

Xi}} + {{SubatomicParticle

Pion}} }} }}

{{math

Charmed Xi+}} }}

{{math

link=yes

link=yes|Charm quark}} }}

{{val

0.4}}

{{sfrac

2}}

({{sfrac

2}}{{thinsp}}+)

âˆ’1

{{val

0.26|e=-13}}

See {{math

charmed Xi+}} }}decay modes

{{math

Charmed Xi0}} }}

{{math

link=yes

link=yes|Charm quark}} }}

{{val

0.4}}

{{sfrac

2}}

({{sfrac

2}}{{thinsp}}+)

âˆ’1

{{val

+0.13

e=-13}}

See {{math

charmed Xi0}} }}decay modes

{{math

Charmed xi'+}} }}

{{math

link=yes

link=yes|Charm quark}} }}

{{val

3.1}}

{{sfrac

2}}

({{sfrac

2}}+)

âˆ’1

{{math

{{SubatomicParticle

Photon}} }}(Seen)}}

{{math

Charmed xi'0}} }}

{{math

link=yes

link=yes|Charm quark}} }}

{{val

2.9}}

{{sfrac

2}}

({{sfrac

2}}+)

âˆ’1

{{math

Charmed xi0}} + {{SubatomicParticle|Photon}}}} }}(Seen)}}

Îžcc++>double charmed Xi

{{math

Double charmed Xi++}} }}

{{math

link=yes

link=yes|Charm quark}} }}

{{val

0.72|errend= Â± 0.27 Â± 0.14}}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

0.256{{SubSup

âˆ’0.022|+0.024}}Â±0.014Ã—10âˆ’12WEB

, Long-lived doubly-charmed particle
, May 2018
, Updates
, CERN
,weblink

{{math

{{SubatomicParticle

Charmed lambda+}} + {{SubatomicParticle

Kaon-}} + {{SubatomicParticle

Pion+}} + {{SubatomicParticle

Pion+}} }} }}

name="dispute"|Some controversy exists about this data. See references}}JOURNAL

, W.-M., Yao
, etal
, Particle Data Group
, 2006
, Particle listings â€“ Îž{{su, +, cc,
|url=http://pdg.lbl.gov/2007/listings/s065.pdf
|journal=Journal of Physics G
|volume=33 |issue=1 |page=1
|arxiv= astro-ph/0601168 |bibcode= 2006JPhG...33....1Y
|doi= 10.1088/0954-3899/33/1/001

}}

{{math

Double charmed Xi+}} }}

{{math

link=yes

link=yes|Charm quark}} }}

{{val

0.9}}{{efn|name="dispute"}}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

e=-14}}{{efn|name="dispute"}}

{{math

{{SubatomicParticle

Charmed lambda+}} + {{SubatomicParticle

Kaon-}} + {{SubatomicParticle

Pion+}}}}}}[e] or {{math

{{SubatomicParticle

Proton+}} + {{SubatomicParticle

D+}} + {{SubatomicParticle

Kaon-}}}}}}[e]

{{math

Bottom Xi0}} }}

{{math

link=yes

link=yes|Bottom quark}} }}

{{val

3}}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

âˆ’1

{{val

+0.28

e=-12}}{{efn

This is actually a measurement of the average lifetime of b-baryons that decay to a jet containing a same-sign {{math

Xi}}Â± {{SubatomicParticle

{{SubatomicParticle

{{SubatomicParticle|Bottom lambda}}.}} }}

See {{math

Bottom Xi}} }}decay modes

{{math

Bottom Xi-}} }}

{{math

link=yes

link=yes|Bottom quark}} }}

{{val

3.0}}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

âˆ’1

{{val

e=-12}}

See {{math

Bottom Xi}} }}decay modes ({{math

{{SubatomicParticle

link=yes|J/Psi}} }} }} was also seen)

{{math

Bottom Xi'-}}}}JOURNAL

, Aaij, R.
, etal
, LHCb Collaboration
, 2015
, Observation of two new {{math, Îž, {{su|p=âˆ’|b=b}} baryon resonances
|journal = Physical Review Letters
|volume = 114 |issue = 6 |pages = 062004
|doi =10.1103/PhysRevLett.114.062004 |pmid = 25723210
|bibcode = 2015PhRvL.114f2004A |s2cid = 6055559 |arxiv = 1411.4849

}}

{{math

link=yes

link=yes|Bottom quark}} }}

{{val

0.02|errend= Â± 0.01 Â± 0.50}}

1/2+

âˆ’1

>{{val

e=-21}}{{efn

name="decaywidth"}}

{{math

Bottom Xi*-}}}}

{{math

link=yes

link=yes|Bottom quark}} }}

{{val

0.12|errend= Â± 0.06 Â± 0.50}}

3/2+

âˆ’1

{{val

0.75

errend= Â± 0.25}}{{efn|name="decaywidth"}}

{{math

Bottom Xi}}}}(6227)âˆ’JOURNAL

, 1805.09418
, Aaij, R.
, CMS Collaboration
, etal
, 2018
, Observation of a new {{math, Îž, {{su|b=b|p=âˆ’}} resonance
|journal = Physical Review Letters
|volume = 121 |issue = 72002 |pages = 072002
|doi = 10.1103/PhysRevLett.121.072002 |pmid = 30169090 |bibcode =2018PhRvL.121g2002A |s2cid =52139397

}}

{{math

link=yes

link=yes|Bottom quark}} }}

{{val

2.0|errend= Â± 0.3 Â± 0.2}}

âˆ’1

3.64{{SubSup

âˆ’0.84

name="decaywidth"}}

{{math

Bottom lambda}} + {{SubatomicParticle

{{SubatomicParticle

Pion-}} }}

name="notobservered"|Particle (or quantity, i.e. spin) has neither been observed nor indicated}}

{{math

Double Bottom Xi0}} }}

{{math

link=yes

link=yes|Bottom quark}} }}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

âˆ’2

name="notobservered"}}

{{math

Double Bottom Xi-}} }}

{{math

link=yes

link=yes|Bottom quark}} }}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

âˆ’1

âˆ’2

name="notobservered"}}

{{math

Charmed bottom Xi+}} }}

{{math

link=yes

link=yes|Bottom quark}} }}

({{sfrac

2}})

({{sfrac

2}}){{thinsp}}+

âˆ’1

name="notobservered"}}

{{math

Charmed bottom Xi0}} }}

{{math

link=yes

link=yes|Bottom quark}} }}

({{sfrac

2}})

({{sfrac

2}}{{thinsp}}+)

âˆ’1

Table notes:

References

External links

REPORT

, Listings for Xi particles
, Particle Data Group
,weblink
, 2007-07-31, dead
,weblink" title="archive.today/20121212045433weblink">weblink
, 2012-12-12

, Direct observation of the strange b baryon Xi(b)-
, Stanford University
,weblink" title="archive.today/20121215010243weblink">weblink

PRESS RELEASE

, Fermilab physicists discover "triple-scoop" baryon
, 2007-06-18
, Fermilab
,weblink
, 2007-06-18

PRESS RELEASE

, Back-to-back b baryons in Batavia
, 2007-06-25
, Fermilab
,weblink
, 2007-06-25

, Observation and mass measurement of the baryon Xi(b)-
, Stanford University
,weblink" title="archive.today/20120526104150weblink">weblink

, {{Particles}}{{Authority control}}

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Xi baryon

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List of Xi baryons

See also

References

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