Cascade Production in K- and Photon-induced Reactions. Collaboration: Benjamin Jackson (UGA) Helmut Haberzettl (GWU) Yongseok Oh (KNU) K. N.

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1 Cascade Production in K- and Photon-induced Reactions Collaboration: Benjamin Jackson (UGA) Helmut Haberzettl (GWU) Yongseok Oh (KNU) K. N. (UGA) KL2016, Feb. 1-3, 2016

2 Our Ξ collaboration:! Theoretical investigation of the reactions: - ΚΝ KΞ γn KKΞ [JLab] [J-PARC] πn KKΞ [J-PARC] pp ΞΞ - - [FAIR] Build a reliable model to analyze the cascade spectroscopy data: Start learning the production mechanism of the established Ξs. [g.s. Ξ 1/2+ (1318)] To date: - ΚΝ KΞ: recent calculations: Sharov, Korotkikh and Lanskoy (EPJA47, 11), Shyam, Scholten and Thomas (PRC84, 11), Feijoo, Magas and Ramos (PRC92, 15), UχPT + high-spin resonances Kamano, Nakamura, Lee and Sato (PRC90, 14), DCC approach they all point to the importance of the S=-1 hyperons γn KKΞ: no calculation is available so far, except for: Liu and Ko (PRC69, 04), in connection with the Ξ 5 production. Our group (PRC74, 06; PRC83, 12), analyzing the CLAS data.

3 KN KΞ

4 KN KΞ : model T = V + VG 0 T = T P + T NP T P = X r F r is r hf r! M s T NP = V NP + V NP G 0 T NP! M u + M c M c M T c ++ = M T c = X L M T c + = M T c + = X L a LT p 0 S b LT p 0 S L exp apple L exp apple LT p02 2 S LT p02 2 S P L ( ) P 1 L ( ) a LT, b LT, αlt = fit parameters Λ S ~ 1 GeV (scale parameter)

5 KN KΞ : model Λ(1116) Σ(1193) Λ(1405) Σ(1385) Λ(1520) the model parameters may be fixed from the relevant decay rates(pdg) and/or quark models and SU(3) symmetry considerations. no enough information to fix the parameters of the model.

6 KN KΞ : model Λ(1116) Σ(1193) Λ(1405) Σ(1385) Λ(1520) the model parameters may be fixed from the relevant decay rates(pdg) and/or quark models and SU(3) symmetry considerations. no enough information to fix the parameters of the model. Σ 5/2- (2250) M = 2270 ± 50 MeV Σ 9/2- (2250) M = 2210 ± 30 MeV [A. de Bellefon et al., N. Cim. A7( 72)]

7 KN KΞ : model Λ(1116) Σ(1193) Λ(1405) Σ(1385) Λ(1520) the model parameters may be fixed from the relevant decay rates(pdg) and/or quark models and SU(3) symmetry considerations. no enough information to fix the parameters of the model. Σ 5/2- (2250) M = 2270 ± 50 MeV Σ 9/2- (2250) M = 2210 ± 30 MeV [A. de Bellefon et al., N. Cim. A7( 72)] Strategy: consider all the 3- & 4-star hyperon resonances which affects the fit quality significantly (δχ 2 /N > 0.1).

8 KN KΞ(1320) : model Λ(1116) Σ(1193) Λ(1405) Σ(1385) Λ(1520) the model parameters may be fixed from the relevant decay rates(pdg) and/or quark models and SU(3) symmetry considerations. no enough information to fix the parameters of the model. W thr 1814 MeV Σ 5/2- (2250) M = 2270 ± 50 MeV Σ 9/2- (2250) M = 2210 ± 30 MeV [A. de Bellefon et al., N. Cim. A7( 72)] Strategy: consider all the 3- & 4-star hyperon resonances which affects the fit quality significantly (δχ 2 /N > 0.1). Λ 3/2+ (1890) Σ 5/2- (2265) Σ 7/2+ (2030) Σ 3/2+ (1385) (g.s. Λ and Σ) on-shell: M 1/2±, M 5/2± (ε N m N )(ε Ξ m Ξ ) M 3/2±, M 7/2± (ε N ± m N )(ε Ξ ± m Ξ )

9 KN KΞ(1320) : model results

10 KN KΞ(1320) : model results

11 KN KΞ(1320) : model results

12 KN KΞ(1320) : model results Model-independent result : (for hard processes) c L = constant p = final state rel. momentum

13 KN KΞ(1320) : model results Model-independent result : (for hard processes) c L = constant p = final state rel. momentum

14 KN KΞ(1320) : model results (efficient P-D destructive interference at low energies) (P-wave supressed) α L = spin-non-flip partial-wave m.e. β L = spin-flip partial-wave m.e.

15 KN KΞ(1320) : model results (prediction)

16 KN KΞ(1320) : model results recoil polarization P

17 KN KΞ(1320) : model results recoil polarization P an opportunity to measure the parity of the g.s. Ξ parity has never been measured [A. Bohr, NPA10, 486(1959)] [K.N., Oh, Haberzettl, PRC89 14] based on Bohr s theorem [π fi = (-) (Mf Mi) ]: π fi = product of the intrinsic parities of all the particles in the final and initial state M f (M i ) = sum of the spin projections of the particles in the final (initial) state along the direction perpendicular to the reaction plane K yy = π Ξ K yy = target-recoil asymmetry (spin transfer coefficient) π Ξ = parity of Ξ

18 KN KΞ(1320) : model results recoil polarization P an opportunity to measure the parity of the g.s. Ξ parity has never been measured [A. Bohr, NPA10, 486(1959)] [K.N., Oh, Haberzettl, PRC89 14] based on Bohr s theorem [π fi = (-) (Mf Mi) ]: π fi = product of the intrinsic parities of all the particles in the final and initial state M f (M i ) = sum of the spin projections of the particles in the final (initial) state along the direction perpendicular to the reaction plane K yy = π Ξ K yy = target-recoil asymmetry (spin transfer coefficient) π Ξ = parity of Ξ T = π Ξ P measure T and P

19 γn KKΞ

20 γn KKΞ : model Nakayama, Oh and Haberzettl (PRC74, 06) Man, Oh and Nakayama (PRC83, 12) K-exchange N/N Ξ/Ξ Y/Y contact current + ( K 1 (q 1 ) K 2 (q 2 ) ) K*-exchange

21 γn KKΞ(1320) : (improved) model results Man, Oh and Nakayama (PRC83, 12)

22 γn KKΞ(1320) : (improved) model results Man, Oh and Nakayama (PRC83, 12) Kaon-exchange: responsible for the forward (backward) angle peaking of the K+ (X-) distribution S=-1 resonances needed

23 γn KKΞ(1320) : (improved) model results Man, Oh and Nakayama (PRC83, 12) above threshold resonances off

24 γn KKΞ(1320) : (improved) model results Man, Oh and Nakayama (PRC83, 12) Kaon-exchange: responsible for the forward (backward) angle peaking of the K+ (X-) distribution above threshold S=-1 resonances needed

25 γn KKΞ(1320) : (improved) model results Man, Oh and Nakayama (PRC83, 12) Λ 3/2+ (1890) Σ 7/2+ (2030)

26 γn KKΞ : beam and target asymmetries t-channel Kaon exchange: Σ = -1 NYK vertex

27 Summary : " KN KΞ(1320) : a) overall, existing data are described well. b) suited for learning about S=-1 hyperon resonances in the 2 GeV mass region: # Hints for the coupling to Σ 7/2+ (2030), Σ 5/2- (2265), Λ 3/2+ (1890) : more accurate data required for a definite confirmation and more complete model. c) P-wave dominance even close to threshold in K - + p K + + Ξ -. total and differential cross section data are consistent with each other. d) for further detailed analysis : more accurate data required. " γp KKΞ(1320) : a) basic features of γp K + K + Ξ - (1318) understood: K-exchange currents : essential for describing the dσ/dω data. (above the threshold S=-1 resonances needed) b) suited for learning about S=-1 hyperon resonances in the 2 GeV mass region: # Hints for the coupling to Λ 3/2+ (1890), Σ 7/2+ (2030) : required to describe m KΞ data. c) more data needed, especially, the spin observables: beam-asymmetry : sensitive to the K-exchange currents (Σ =-1). target-asymmetry : sensitive to the ps-pv mixing in the KNY couplings.

28 The End