Charmed Baryon Production (Charmed baryon Spectroscopy via p(  -,D* - )Y c ) 11 Sep., 2013 H. Noumi RCNP, Osaka University 1

2 What are good building blocks of Hadrons? Constituent Quark q q q q q Diquark? [qq] q (Colored cluster) hadron (colorless cluster) q q q q q

How to form baryons? 3 q q q Most fundamental question Interaction btwn quarks Diquark correlations 3 [qq]-pairs in a Light Baryon How to close up diquark correlations

Charmed Baryon 4 Q qq Weak CMI with a heavy Quark [qq] is well Isolated and developed Level structure of Y c * Decay Width/Decay Branching Ratios, etc. V CMI ～ [  s /(m i m j )]*( i  j )(  i  j )

5 Hydrogen Target    20 GeV/c   Beam Dispersive Focal Plane High-resolution, High-momentum Beam Line High-resolution, High-momentum Beam Line D*  Spectrometer Missing Mass Spectrum Missing Mass Spectroscopy Measure D* - Charmed Baryon Spectroscopy (P50)

Charmed baryon spectrometer Modified design FM cyclotron magnet J-PARC E16 ⇒ 2.3 Tm, 1 m gap High rate detectors ­ Fiber, SSD Large detectors Internal detectors ­ DC, RPC PID: RICH ­ Hybrid radiator  LH 2 -target Ring Image Cherenkov Counter Internal DC FM magnet ss  SSD Fiber tracker Beam GC Internal TOF DC TOF wall 2m Decay   Beam   Large acceptance multi-particle spectrometer system Multi propose spectrometer

＊ D* tagging: > 10 6 reduction ⇒ Other event selection ○ Forward scattering angle cut ⇒ Reduction ( GeV/c 2 ) = 15 ­ Signal acceptance = 0.54 ­ 1900 → 1000 counts Background reduction 3 K  cm KK ss D0sD0s DD Reduction S/N  D0 15×2.0×10 6 reduction background W/ signals

Background spectrum Clear peak 1 nb/peak case ＊ Main background structure is dominant. ⇒ Achievable sensitivity: nb (3  level,  < 100 MeV) Sum Main BG (s-production + Miss-PID) Associated charm production BG W/o signal W/ signal: 1900 counts/peak W/ signal: 1000 counts/peak W/o signal Only D* taggingW/ event selection

Decay measurement Method: Mainly Forward scattering due Lorentz boost (  < 40°) ­ Horizontal direction: Internal tracker and Surrounding TOF wall ­ Vertical direction: Internal tracker and Pole PAD TOF detector Mass resolution: ~ 10 MeV(rms) ­ Only internal detector tracking at the target downstream PID requirement: TOF time difference (  & K) ⇒  T > 500 ps ­ Decay particle has slow momentum: < 1.0 GeV/c Beam Target Magnet pole Beam Target Internal tracker Pole PAD TOF wall Surrounding TOF wall Magnet pole

Basic performances Acceptance ­ 50  60% ○exp(bt) (t-channel, b = 2 GeV  2 ) ­ 1 nb case: ~1900 counts ○4 g/cm 2 LH 2 target, 8.64×10 13   (100 days) ○  all = 0.55 ­ Acceptance for decay particles: ~85% ○  c (2940) + →  c (2455) 0 +   ○  c (2940) + → p  D 0 ＊ Compare coverage cos  >  0.5 Resolution ­  p/p = 5 GeV/c ­ Invariant mass resolution ○D 0 : 5.5 MeV ○Q-Value: 0.7 MeV ­ Missing mass resolution ○  c + : 16.0 MeV ○  c (2880) + : 9.0 MeV ­ Decay measurement ○  M ~10 MeV exp(bt) Isotropic in CM Acceptance: D*  detection Decay angle:  c (2940) + →  c (2455) 0 +   Forward direction (Beam direction)

Tagged missing mass spectra ＊ Full event w/ 1 nb Continuum background around the peak region Signal counts ­  c  mode: ~230 counts ­ p D mode: ~320 counts  c 0    c ++    c +     p D 0 SUM Signal Main BG c0c0  c ++ c+c+ D0D0

Tagged missing mass spectra ＊ Full event w/ 1 nb Selecting  c +     decay chain ⇒ Background level was drastically decreased. Signal counts ­  c  mode: ~230 counts ⇒ ~200 counts ­ p D mode: ~320 counts  c 0    c ++    c +     p D 0 SUM Signal Main BG c0c0  c ++ c+c+ D0D0

What We can Learn from P50… Production Cross Section Not only for feasibility but also… – Production Mechanism (Hosaka-san) Does the Regge model work? (large s & small |t|) – Coupling Constant/Form Factor -> LQCD? What does the state population tell us? – Spin/Isospin Structure – Wave Functions (Q-Diq picture or others) – So-called rho-mode (di-quark) excitation? – Application of pQCD (Kawamura-san) Applicable at large s &|t| (Hard process)? Prediction from pQCD Are there any feedback from the P50 measurement?

What We can Learn from P50… Expected Spectrum – Excitation Energy and Width Baryon Structure Can we see a Quark-diquark picture? Decay Property – Decay branch/partial width Baryon Structure –  (Y c * -> pD)/  (Y c * ->  c ) ? – Angular Distribution Spin/Parity

Charm production Cross Section No exp. data for the p(  ,D*  )  c is available but σ<7nb at p  =13 GeV/c at BNL (1985)

Charm production Cross Section Photoprod. of  c D* bar X on p at E  =20 GeV. –  (  c D bar X ) =44± nb –  (D - X)=29± nb –  (D* - X)=12± nb  (  c D* bar X ) ~ 18 nb This seems sizable. Abe et al., PRD33, 1(1986) D*  C, X p 

Charm production Cross Section  (  N→J/ψX) = （ 1±0.6 ） nb and (3.1±0.6)nb at 16 GeV/c and 22 GeV/c. – OZI-suppressed process! J/ψ X N  LeBritton et al., PLB81, 401(1979)

Comparison in strange sector OZI-suppressed process in Strange Sector –  (   p→  n) = （ 1.66±0.32 ） nb at 4 GeV/c. –  (   p→   p) = （ 9.5±2.0 ） nb at 3.75 GeV/c ->  (  N→  N)/  (  N→  X)~1/10? OZI-non-suppressed process –  (   p→    ) = （ 53±2 ） nb at 4.5 GeV/c ->  (   p→    )/  (  N→  X)~2? -> ???  (   p→D   c )/  (  N→J  X)~2? Crennell et al., PRD6, 1220(1972) Avres et al., PRL32, 1463(1973) Gidal et al., PRD17, 1256(1978)

Comparison in strange sector s/s 0  (  b) ∝s-∝s-

Theoretical Estimations t-channel PS meson exchange Comment on the pQCD model Regge Model: revisit

Revisit the Regge Theory shows the typical s-dependence of binary reaction cross sections at the large s region; – Regge trajectory: – scale parameter s 0 : s at the threshold energy of the reaction AB → CD (*In Kaidalov’s Model: s 0 2(  D* (0)-1) =s CD    0)-1 *s CD  J/   0)-1 s AB =( Σ m i ) A *( Σ m j ’) B, m i :transversal masses of the consituent quark) Treatment of  (-  (t)) to avoid possible singularities – Actually introduce phenomenological form factor  (-  (t)) →  (-  (t 0 )): naïve Regge →  (1-  (t 0 )) : Kaidalov’s Regge [Z. Phys. C12, 63(1982)] → exp(R 2 t): Grishina’s Regge [EPJ A25, 141(2005)] discussed with A. Hosaka

Regge Theory PS(K,D)-Regge (Top): s/c-prod: ~10 -5 (Naïve), ~3x10 -5 (Kaidalov) V(K*,D*)-Regge (Bottom): s/c-prod.: ~10 -4 (Naïve), ~3x10 -5 (Kaidalov) calculated by A. Hosaka  (0)  T 1/2 (GeV) K D K* D* s/s   (arb.) s/s  s 0 (GeV 2 ) Naïve K*  K*  c Kaidalov K*  K*  c Regge Trajectory Scale Parameter p  =20 GeV/c

Regge Theory Normalization with  (p(  -,K*)  ) data [ PR163, 1377(1967), PRD6, 1220(1972) ] – Naïve Regge shows a steeper s-dependence – Grishina’s Regge with R 2 =2.13 GeV -2 reproduces data well. Charm production: ~10 -4 of strangeness production, → We expect  (p(  -,D*)  c ) close to 10 nb at p  =20 GeV/c. s/s   (  b/sr)  (-  (t 0 )) exp(R 2 t)  (-  (t 0 )) exp(R 2 t)  (-  (t 0 )) exp(R 2 t)  (p(  -,K*)  )/  (p(  -,D*)  c ) s/s  p(  -,K*)  p  =20 GeV/c p(  -,D*)  c Ratio of s- to c-prod.

Comment on the Coupling Constant Comparison of g D*D*  /g K*K*   and  g  cND /g  NK* – Estimated by means of the Light Cone QCD Sum Rule – Exp. Data Taking g D*D*  /g K*K*   g  cND* /g  NK*  → We expect  (p(  -,D*)  c )  a few nb. g K*K*  g D*D*  g D*D*  /g K*K*  3.5* g K*K  g D*D  g D*D  /g K*K  4.5* A. Khodjamirian et al. EJPA48, 31(2012) g  NK* g  cND* g  cND* /g  NK* g  NK g  cND g  cND /g  NK g K*K  g D*D  g D*D  /g K*K  ~ ~ M.E. Bracco et al. Prog. Part Nucl. Phys. 67, 1019(2012) *note:g[Bracco]/2=g[Khodjamirian] 24

25 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. 25 Hosaka-san

Excitation Energy Dependence Production Rate in a quark-diquark model: – D* exchange at a forward angle – Radial integral of wave functions Taking Harmonic Oscillator Wave Functions I ~ (q eff /A) L exp(-q eff 2 /2A 2 ) I ~ (q eff /A) L exp(-q eff 2 /2A 2 ), where A: oscillator parameter (0.4~0.45 GeV) q eff ~ (q eff /A) L For larger q eff, the relative rate of a higher L state to the GS increases as ~ (q eff /A) L – Spectroscopic Factor:  pick up good/bad diquark configuration in a proton A residual “ud” diquark acts as a spectator – Kinematic Factor w/ a propagator : – Spin Dependent Coefficient, C: Products of CG coefficients based on quark-diquark spin configuration Characterized by the spin operator in the vector meson exchange, u c “ud” D*  f g YcYc p discussed by A. Hosaka  =1/2 for  c ’s =1/6 for  c ’s

Estimated Relative Yield p  =20 GeV/c  c 1/  c 1/  c 3/  c 1/  c 3/  c 1/  c 3/  c 1/  c 3/  c 5/  c 5/  1/21/6 1/2 1/6 ½ C11/98/91/32/31/272/27 56/1352/53/5 K q eff R (Rel.) The estimation is valid for the D* exchange at a very forward angle. The yields for some of  c ’s are suppressed due to  and C. The C coefficient is characterized by spin dependent interaction at the D*NY c vertex. Those for  c ’s are not suppressed very much at the excited states. |I| reduces (increases!) an order of (q eff /A) L at higher L states. 27 calculated by A. Hosaka

Estimated Relative Yield (strange sector) p  =4.5 GeV/c  1/  1/  3/  1/  3/  1/21/6 1/2 C11/98/91/32/3 K q eff R (rel.) Exp(  b/sr) The yield for  1/2+ is suppressed due to  and C. The estimation is not very far from the experimental data but for  ’s. This already suggests a necessary modification of the model. The measurement in charm sector provides valuable information on the reaction mechanism and structure of baryons. Exp.: p(  ,K 0 )Y, D.J. Crennell et al., PRD6, 1220(1972) 28 calculated by A. Hosaka

Production Rate 29

30  c (1/2 + )  c (1/2 - )  (1/2 + )  (1/2 - ) q eff =1.33 GeV/c q eff =1.37 GeV/c q eff =0.29 GeV/c q eff =0.27 GeV/c L=0 r {fm} L=1 charm strange

Summary… Experimental Design – 1000 count/nb/100d – Background reduction Signal Sensitivity: 0.1~0.2 nb for  ~100 MeV state 1 Decay particle detection inprove S/N very much – Improve the acceptance Decay particle Acceptance Production Rate – A few nb for  c production seems a plausible estimation Excitation Energy Dependence – The production rate is kept even at higher L spin/isospin structures – The production rate is kept even at higher L states, depending on spin/isospin structures of baryons. – How are the rho-mode states excited? How can we extract “diquark” in baryons Can we can learn characteristic baryon structures from – Excitation Energy Spectrum – Population (Production Rate) – Decay (Partial) Width/Branching Ratio – Angular Correlation – What is similarity to/difference from strange baryons 31

Structure and Decay Partial Width 32 Excited (qq)Good [qq]  (1520) -> NK (D wave!)>π , similarly  (1820),  (2100) Possible explanation of narrow widths of Charmed Baryons Illustrated by Hosaka

33 Possible Subjects Charmed Baryon Spectroscopy N*, Y* resonances via ( ,ρ), ( ,K*)  ’, , , J/ , D, D* productions off N/A “K - K - pp” strongly interacting hadronic system S=-1, -2, -3 baryon spectroscopy w/ K beam others We welcome you to join !