Diquarks in heavy baryons Atsushi Hosaka (RCNP, Osaka U. ） 9/10-13, 2013Charmed baryons1 Practical questions of hadron physics How ground and excited states are described? Are there simple language for it when quarks and gluons interact strongly Are there kinds of quasi-particles interacting weakly Constituent quarks: Mere useful tool of symmetry realization or Dynamically realistic and active object How can diquarks be be identified in multi-quark systems Baryons, nuclei, nuclear matter, quark matter

Quark-diquark baryon Selem-Wilczek: e-Print: hep-ph/ hep-ph/ ee has repulsive force, BUT qq has attractive force SU(3) c : half of qq bar attraction SU(2) c : Same as qq bar  Pauli-Gursey symmetry ~ several hundred MeV Diquark can be seen better in heavy baryons than in light Color magnetic int. Good Bad

Some evidences 9/10-13, 2013Charmed baryons3 Σ-Λ (80 MeV), Σ c -Λ c (215 MeV) mass difference Production rate of Λ, Σ GeV) Λ : Σ = 0.08:0.023, Λc : Σc = 0.074:0.014 ΔI = ½ rule F 2 n /F 2 p  ¼ Lack of exotics  Repulsive between good diquarks?

In QCD 9/10-13, 2013Charmed baryons4 How diquarks are defined? -- correlation function ud-diquark Heavy quark t = 0 2t t How are they observed in charmed baryons? Spectrum, decay rate, production Are there other opportunities to hunt diquarks? qq interaction in a baryon (colored environment)

Density correlations 9/10-13, 2013Charmed baryons5 Alexandrou, deForcrand, Lucini PRL 97, (2006) cosθ 1.0 r θ r = 0.69 fm r = 0.47 fm r = 0.35 fm Good diquark Bad diquark Indicates significant attraction between quarks in good diquark pair

Baryon spectrum S=1/2 S=3/2 qqq qq c q cc c I Light flavor baryons (uds) Ground and excited ~ 80 states 9/10-13, 2013Charmed baryons6 uds

S=3/2 S=1/2 Charmed baryons 14 c ＋ 1 cc << 80 uds (6 excited ) 1/2 + 1/2 – 1/2 + 3/2 + 1/2 – 1/2 + 3/2 + 3/2 – 5/2 + ? ΞCΞC [GeV] ? 1/2 + 3/2 + ΩCΩC cqq csq css ΞCΞC Ξ’ C 1hω ? 1 Ξ + cc 9/10-13, 2013Charmed baryons7

Advantage of heavy quark Discriminate of modes Light baryon One HQ baryon Two HQ baryon Spectrum, productions and decays 9/10-13, 2013Charmed baryons8

λ and ρ motions split  known as isotope shift  q  q, SO  c (1/2-,3/2-) Λ c ( 1/2-,1/2- 3/2-,3/2-, 5/2- ) Λ c (1/2-,3/2-) Σ c (1/2-,1/2- 3/2-,3/2-, 5/2- )  c (1/2+,3/2+) Λ c ( 1/2+ ) “Q” may isolate “qq” q q q Q  q-q Q  λ mode ρ mode G.S. 9/10-13, 2013Charmed baryons9

Decays Ratio: 9/10-13, 2013Charmed baryons10 ρ-mode λ-mode ρ-mode バリオンは軽い中間子と重いバリオンに λ-mode 重い 軽い に崩壊

9/10-13, 2013Charmed baryons11 1/2 –  1/2 + E1 transition λ mode Good diquark 0 + l λ = 1 3P0 diquark 0 – lρ = 1 ρ mode 0 –  0 + is forbidden Good diquark 0 +

9/10-13, 2013Charmed baryons12 5/2 –  1/2 + M2, E3 transition λ mode 3 S 1 diquark 1 + l λ = 1 3 P 2 diquark 2 – lρ = 1 ρ mode 2 –  0 + is M2 Good diquark 0 + Both M2 E3

Role of a heavy quark 9/10-13, 2013Charmed baryons13 Filter out 2-body correlations Excitation spectru, λ-ρ modes, Good vs bad diquark Decay pattern, selection rules Diquark densities Establish diquarks from QCD  Phenomena