Charmed Baryons Productions and decays

Transcription

1 Charmed Baryons Productions and decays Atsushi Hosaka RCNP, Osaka University Reimei( ), Jan.17-20, 2016 Collaborators: Noumi, Shirotori, Kim, Sadato, Yoshida, Oka, Hiyama, Nagahiro, Yasui PTEP 2014 (2014) 10, 103D01 PRD92 (2015) 9, PRD92 (2015) 11, Introduction 2. Structure Masses and WF 3. Production 4. Decays Studied at J-PARC Reaction rates and structure, WF Jan ,

2 1. Introduction X(3872) Exotic threshold phenomena Z(10610, 10650) Pc(4380, 4450) M max (πj/ψ) (GeV/c ) Jan , Events / 0.02 GeV/c Z(3900) data Fit Background PHSP MC

3 Multiquarks, correlations near the threshold 4.2 Z(4430) Meson molecules Diquark Tetraquark qq qqqq qq 3.8 Z(3900) X(3872)?? creation and rearrangement of multiquarks Correlations qq hadrons qq diquarks Jan , qq

4 Charmed baryons for the study of qq dynamics [GeV]? 5/2 + More states at J-PARC? 1/2? 3/2 + Excited states ρ λ 3/2 1/2 1hω 1/2 + 3/2 + 1/2 + 3/2 + 1/2 + Ξ C csq Ξ C Ξ C 1/2 + Ω C css Disentangle the role of qq Ground states λ ρ 1 Ξ + cc cqq cqq Feb.16 - Mar.21, 2015 HHIQCD, YITP 4

5 2. Structure: what do we expect to study? A heavy quark distinguish the fundamental modes λ and ρ Place to look at qq dynamics Isotope-shift: Copley-Isgur-Karl, PRD20, 768 (1979) ρ ρ qq λ λ λ ρ m Q,m Q Jan , 2016 ρ = λ ρ λ m Q = m u,d m Q Smooth change in mq is useful 5

6 Negative parity states p-wave excitations - 1/2, 3/2 Quark model 3-body calculation Yoshida, Sadato, Hiyama, Oka, Hosaka arxiv: (2015) Model Hamiltonian H = p p p 2 3 2m q 2m q 2M Q P2 2M tot + V conf (HO) + V spin spin (Color magnetic) +... Solved by the Gaussian expansion method Jan ,

7 Excitation energies p- wave states M = m M = m s 0.7 ρ mode M = m c HQ singlet Σ(5 / 2 ) Σ(3 / 2 ) Σ(1/ 2 ) Λ(5 / 2 ) Λ(3 / 2 ) Λ(1/ 2 ) HQ doublet M [GeV] 5 λ mode Jan ,

8 Wave functions, ρ and λ mixing Mixing of Λ(phys) = c λ Λ( 2 λ) + c ρ Λ( 2 ρ) e.g. λ-mode dominant state: How much the other mode mixes? λ mode prob Probability c 2 Strange Λ solid Σ dashed ρ mode prob Charm Λ c * is almost pure λ mode Reflect more qq nature SU(3) M Q [GeV] Heavy quark Jan ,

9 3. Productions π + N à D * + Λ c i O f Jan ,

10 3. Productions π + N à D * + Λ c A. B. Kaidalov and P. E. Volkovitsky, B. Z. Phys. C 63, 517 (1994) Reaction dynamics Regge model i O f How much is charm produced? Jan ,

11 3. Productions π + N à D * + Λ c A. B. Kaidalov and P. E. Volkovitsky, B. Z. Phys. C 63, 517 (1994) Reaction dynamics Regge model i O f How much is charm produced? PTEP 2014 (2014) 10, 103D01, PRD92 (2015) 9, How are they related to internal structure? Jan ,

12 dσ [µb / sr] dω π p ΛK *0 π p ΣK *0 p π, Lab = 4.5 GeV 10 D.J. Krennel et al PRD6, 1220 (1972) , Dec cosθ cosθ 12

13 Regge model description Kim Hosaka Kim Noumi, arxiv: π + N K *0 + Λ of threshold whereas its effect becomes much smaller as s increases. This can od from the behavior of the u-channel Regge amplitude: T Σ s Note that of Σ reggeon exchange is significantly different from that of Σ exchange in the rangian method, where the u-channel makes a negligibly small contribution (see mparison). σ [µb] K R K * R N Σ R total How much is charm produced? π p -> K *0 Λ s/s th [Regge] P lab = 3.95 GeV/c t GeV 2 Vector-Reggeon dominance with some pseudoscalar Energy dependence is also well produced lor online). Each contribution to the total cross sections for the π p K 0 Λ reaction nction of s/s th, based on a Regge approach. The dotted and dashed curves show the s of K reggeon exchange and K reggeon exchange, respectively. The dot-dashed one ect of the nucleon in the s-channel, whereas the dot-dot-dashed one depicts that of Σ ange in the u channel. The solid curve represents the total result. The experimental en from Ref. [24] (triangles) and from Ref. [25] (circles). Jan , dσ/dt [µb/gev 2 ]

14 Prediction to the charm production 10 2 π p -> ( K *0 Λ & D *- Λ c + ) [Regge] σ [µb] K *0 Λ D *- Λ c s/s th Jan ,

15 How are they related to internal structure? PTEP 2014 (2014) 10, 103D01 N i O f Various YC Quark model wave functions Jan ,

16 Dynamical part ~ radial integral q(p i ) c(p f ) q eff : the momentum transfer ~ Large GS d Excited states B c (S-wave) e! σ! e i! q eff!x N(S-wave) radial ~ 1 exp q 2 eff 4A 2 B c (P-wave)! e! σ e i! q eff!x N(S-wave) radial ~ q eff A 1 exp q 2 eff 4A 2 B c (D-wave)! e! σ e i! q eff!x N(S-wave) radial ~ 2015, Dec Transitions to excited states are not suppressed q eff A 2 exp q 2 eff 4A 2 16

17 Results Charm k π CM = 2.71 [GeV], k π Lab = 16 [GeV] Feb.16 - Mar.21, 2015 HHIQCD, YITP 17 Strange k π CM = 1.59 [GeV], k π Lab = 5.8 [GeV]

18 Charm production spectrum Ground state Excited states l = 0 l = 1 1/ 2 + 1/ 2 3 / 2 HQ doublet J = j l + s H = j l ±1/ 2 l = 2 3 / / : 2 2 : 3 Jan ,

19 Similarity Establishing single particle orbits: 89 Y f1/2, 3/2 d1/2, 3/2 p1/2, 3/2 s1/2 H.#Hotch#et#al.,## Phys.#Rev.#C64,#044302(2001)# Jan ,

20 π + p D * + B c* (J P ) s p d π Y K ΛY(J P ) d Jan ,

21 π + p D * + B c* (J P ) p s d π Y K ΛY(J P ) s p d Jan ,

22 4. Decays Pion emission N π Y c * M c Y c * Y c Jan ,

23 4. Decays Pion emission... On going, Nagahiro, Yasui,,, Unique feature ~ very near the threshold Λc(2625, 3/2 ) l = 1 Λ (2595, 1/2 ) c p = 102MeV p ~ 0 MeV Σc(2455, 1/2+) Ground states l=0 p = 94MeV Λc(2286, 1/2+) Place to look at the two independent operators π!!!!!! σ q!! σ p, σ p i f p p f i * Λc Σc µ q γ q φ, q γ γ 5 q µ φπ 5 π Jan , 2016 Reimei WS@J- PARC 23

24 Example { ( )( ) } ( ) ( ) Λ c(1/2, λ-mode) + Σ gs c (1/2 + ) ++ π { λ ( ) (1 ) it σ = ig ω π 2 2M Λ 2MΣ m 3 2 q qλ λ + q ρ e q 2 λ 4a 2 λ e q 2 ρ 4a 2 ρ 2aλ ( ) ( ) it q σ = ig q M 2 2M Λ 2MΣ m 2m + M ω q π 2m ( 1) λ e q 2 λ 4a 2 λ e q 2 ρ 4a 2 ρ 3 2aλ Form factor a: Wave function parameter q: Pion momentum π Jan ,

25 Ground (1/2, 3/2 + ) > Ground (1/2 + ) B i J P Γ full exp(γ i ) q Γ th (Σ c (J + ) ++ Λ gs c (1/2 + ;2286) + π + ) (MeV) (MeV) (MeV) (MeV) Σ c (2455) 1/ (2.26) ( ) (2.26) (ω π =0limit) Σ c (2520) 3/ (14.9) (2517.9) (ω π =0limit) 1/2 > Ground (1/2 + ) Preliminary results g A q = 1 g A N = 5/3 Γ th (Λ c(j ) + Σ gs c (2455; 1/2 + ) ++ π ) B i J P Γ full exp q λ-mode ρ-mode (MeV) (Γ i ) (MeV/c) doublet singlet doublet doublet (MeV) 1/2 3/2 1/2 1/2 3/2 3/2 5/2 Λ c (2595) 1/2 2.6 π ( ) (0.624) π total Λ c (2625) (3/2 ) < ( ) (0.0485) Jan , 2016 x 3 x 3 Λ c (2765)?? (2766.6) (not seen)

26 Decays right on the threshold Λ c 2595; 1/2 + Σ c π : π π + π Finite Γ Σc Λ c Λ c Σ c gs Σ c gs++ π + Finite Γ Σc Λ c gs+ Λ c gs+ Γ = 2.6 MeV 24 % = 0. (isospin sym. assumed [P = MeV = MeV M Λ(2595) < M Σ m π Γ π = 0? Oct. 5-10, 2015 Partial decay width Γ i [MeV] (~transition cross section) 8 Partial decay width Γ i [MeV] (~transition cross section) M Σ m π Γ π s [GeV] NUFRA H. Nagahiro Γ π 0 > Γ π ~ phase space Γ π Λ c Λ c / /2 ~ 138 MeV 26

27 Summary Heavy quarks identify and disentangle different modes of baryons, ρ and λ modes Productions are useful for structure study A similar feature with hyper nuclei Charm baryons could be abundantly produced Decays are useful to further understand the structure Jan ,

28 1. Introduction Hyper nuclei Λ Go into deep inside Established shell structure Charmed baryons ρ λ Q Causes isotope- shift Will discriminates modes Three particles Internal ρ and λ modes Jan ,

29 Another interest: Exotics - Multiquarks Jan ,

30 LHCb found Pentaquarks = cc bar uud TeV pp collision > Λ b Λ b J /ψ, p!" # $#, K ] 2 [GeV ψp J/ m LHCb mkp 2 [GeV ] Jan ,

31 2. Structure: what do we expect to study? A heavy quark distinguish the fundamental modes λ and ρ Place to look at qq dynamics Isotope-shift: Copley-Isgur-Karl, PRD20, 768 (1979) ρ λ ρ = λ Jan ,

32 4. Decays N π Y c * M c Y c * Y c Jan ,

33 ρ-modes Decays of baryons π J P J P + π(0,l π ) Jan ,

34 ρ-modes Decays of baryons = of diquarks j P j P + π(0,l π ) π J P J P + π(0,l π ) Two conditions must be satisfied for baryons and for diquarks Λ c (1/ 2,ρ) Σ c (1/ 2 +,GS) + π d( 3 P 0 ) d( 3 S 1 ) + π is not allowed Jan ,

35 Model Hamiltonian H = p p p 2 3 2m q 2m q 2M Q P2 2M tot + V conf (HO) + V spin spin (Color magnetic) +... Solved by the Gaussian expansion method Jan ,

36 ωω ρλ = ω λ ρ m M 1/2 = 1 ( 1+ 2x ) 3 1/2 cqq bqq ccq qqq bbq &2012 JPARC<Collab M/m Jan ,

37 Strategy: Forward peak (high energy) à t-channel dominant We look at: (1) Absolute values by (Λ c /Λ s ) by the Regge model, K*, D * Vector-Reggeon (2) Ratios of B c *(λ modes) / B c by a one step process of Qd picture for λ-mode Pion-induced reaction π + p à D * + B c * π D * Jan , p d D * Reggeon Quark model WF B c *

38 Unique feature ~ very near the threshold Λ c *(2625, 3/2 ) Λ c *(2595, 1/2 ) ~ 140 MeV Σ c (2455, 1/2 + ) Place to look at the two independent operators Λ c * 4. Decays Pion emission! p i! σ! q On going, Nagahiro and Yasui π! p f Σ c p = 102MeV; allowed p ~ 0; marginally allowed p = 94MeV; allowed Λ c (2286, 1/2 + )! σ! p i,! σ! p f qγ 5 qφ π, qγ µ γ 5 q µ φ π Jan ,

39 Actual computations Λ c * (P-wave excitations, J P ) Σ c (2455, 1/2 + ) + π π Quark model (H.O.) wave functions λ ρ Sd = 0, 1 l λ,ρ = 1 S Q = 1/2 } J Light = 0,1,2 JTotal }= 1/2, 3/2, 5/2 } } HQ doublet HQ singlet m = 0.4 GeV, k = 0.03 GeV 3 M = 1.5 GeV R2 1/2 = 0.5 fm g A (q) = 1, f π = 93 MeV L πqq = g A (q) Jan , f π qγ µ γ 5 q µ φ π

40 Initial baryons Λc * Λc(2595) Λc(2625) Λc(2765) Σc?, Λc(2880) Λc(2940) Γexp (full ) [MeV] p [MeV] Γcalc(Λc * > Σc(2455) π) [MeV] λ-mode, lλ=1 ( ρ-mode, lρ=1 Doublet d( 1 S0) [lλ, c] 1/2, Singlet [d( 3 P0)] 1/2 Doublet [d( 3 P1) c] 1/2, 3/2 Doublet [d( 3 P2) c] 3/2, 5/2 1/2 3/2 1/2 1/2 3/2 3/2 5/ * * * * * * * < 0.97 (102) 50 (262 ) 5.8 (376) 17 (427) ** ** ** ** * Almost threshold carefully studied, ** Forbidden (selection rule) 1/2 : s- wave πσ decay 3/2, 5/2 + : d, f- wave πσ decay > suppressed by power (q/a) 4, 6 Λ c (2880) and Λ c (2940) could be higher spin states? Jan ,