Production rates of Strange and Charmed baryons at

Production rates of Strange and Charmed baryons at Belle Nuclear physics consortium string @ s = 10. 52 Ge. V 1

Production rate of hadrons Slope of meson (qqbar) is different from baryons (qqq). Slope depends on quark counting s/shad/(2 J+1) Production rate s/shad/(2 J+1) exp(-amh) due to linear potential “ 4 or 5 -quark state” do not lie on “ 3 -quark state”? L(1405), pentaquark, Q+? mh(mass of hadrons)[Ge. V] 2

Previous data LEP s=92 Ge. V L(g. s. )/L(1520) deviate in LEP good di-quark > bad di-quark? L(1520)[3/2 -] deviates in ARGUS [3/2 -] state is special? L=0 ≠ L=1 ? L(1520) [3/2 -] Lc*(2625)[3/2 -] L(1405) [1/2 -] Lc*(2595)[1/2 -] s/shad/(2 J+1) R. L. Jaffe, Phys. Rept. 409: 1 -45, 2005 ARGUS s=10. 5 Ge. V Error bar in ARGUS is large More precise data Belle deviate No series of charmed baryon First systematic measurement of production rate for charmed baryons. Mass of baryons (Ge. V) 3

Diquark picture • Interaction between quarks • Diquark correlations Strange baryons q q q (L[uds], S[uds]) mu, md ≈ ms (qqq) uniform Charmed baryon (Lc[udc], Sc [udc]) q q Q Diquark correlation is enhanced by weak Color Magnetic Interaction with a heavy quark mu, md << mc diquark + quark (qq) (Q) qq ( ) S=0 “good” diquark ) S=1 “bad” diquark 4

Strange baryon & Charmed baryon Strange baryons Charmed baryons L, S Lc , S c diquark + Quark [qq] [c] [qqs] uniform S=0 u d s L S=0 S=1 u d s S u u L c S=1 d L d c Lc > Sc good di-quark > bad di-quark due to strong attractive force of good diquark 5

In this work Systematic study of baryons to search for “exotic” baryons in strange and charmed baryons. Information on diquark picture of charmed baryons in contrast with strange baryons. L, S, S*, X, W, Lc* , Sc* First systematic measurement for series of charmed baryons. It is interesting and important to look at the tendency of many baryons by precise measurement. Belle data, well constructed detectors and good statistics. 6

Data of Belle Aerogel Cerenkov Cs. I calorimeter Time Of Flight S. C. solenoid 3. 5 Ge. V e+ 1. 5 T 8 Ge. V e- Silicon Vertex Detector KL μ system Central Drift Chamber Integrated luminosity 79. 366 fb-1 @ s = 10. 52 Ge. V 702. 623 fb-1 @ s = 10. 58 Ge. V ϒ(4 S) 7

Good vertex reconstruction Profile of interaction point (IP) SSD placed in 3 cm/2 cm from Interaction point (IP), and low materials. Resolution of reconstructed vertex for B J/Psi Ks is about 80 mm. Good for hyperon (long life) reconstruction. 8

Hyperon reconstruction Decay processes • X- Lp • W- LK • Wc 0 W-p+ • L p p • S 0 Lg • S*(1385)+ Lp+ p- momentum vector of L p p- p IP Interaction point L ct = 7. 89 cm ct=7. 89 cm X-/W- Dx p+ (S 0 o ) rg (S * + ) IP ct = 4. 91 cm / 2. 64 cm p+ for Wc 0 p- 9

ds/dxp L L / Lbar m li e r p ry a in Mass spectrum of L Xp “Inclusive” total cross section Feed down processes from higher states L + Lbar = 373. 9 ± 0. 5 pb 10

Mass spectra S 0(1192) Lg(BR~100%) real data events in 0. 3 < xp <0. 4 S*(1383)+ Lp+(BR=87%) real data events in 0. 3 < xp <0. 4 11

S 0 +c. c. ds/dxp “Inclusive” cross sections vs. xp li e r p S*+ +c. c. ry a in m Xp Inclusive total cross section S 0 + S 0 = 97. 0 ± 1. 5 pb Xp Inclusive total cross section S* + S* = 33. 2 ± 2. 4 pb 12

direct cross section of L • feed-down were subtracted from inclusive cross sections. • Isospin symmetry was assumed for S* and X production cross-sections. Result (inclusive) 13

direct S 0 and S*+ production • feed-down were subtracted from inclusive cross sections. • Isospin symmetry was assumed for S* and X production cross-sections. Result S*+ + c. c. (direct) : 33. 2 ± 2. 4 pb - 0. 4 ± 0. 06 pb = 32. 8 ± 2. 4 pb S*+ + c. c. (inclusive) L(1520) + c. c. 14

L(1520) Select p and K- from IP with cuts for distance from IP Mass spectrum of L(1520) ○○ (4 S) data ▽▽ Continuum data Y / anti-Y m li e r p ry a in L(1520) p. KBR=22. 5% 15

Direct cross section L(1520)+c. c. (direct) = 15. 3 ± 0. 5 pb – 0. 34 ± 0. 17 pb = 15. 0 ± 0. 26 pb inclusive Lc + 16

Mass spectrum of X- and W- X- W- 17

Cross sections of X and W X/X W/W ●● ＠ 10. 58, (4 S) data ○○ ＠ 10. 52, Continuum data Y / anti-Y ry a in m li pre X + Xbar inclusive cross section = 25. 55 +- 0. 64 pb W + Wbar inclusive cross section = 1. 15 +- 0. 32 pb 18

+c. c. Event rate / Lint. Counts Wc + Wp Mass [Ge. V] s x BR (W-p+) + c. c. = 0. 04 0. 003 pb Wc W-X = 0. 2 pb m i l e pr ry a in xp BR 1. 25± 0. 5% for W-X 0. 25± 0. 12% for W-p+ by phenomenological calculation (ref. PDG) 19

Lc+, Lc*+, Sc 0, and Sc*0 Decay process analyzed in this work Lc + • Lc*(2625) • S c 0 • Sc*(2520) • p. K-p+ Lc + p - + c. c. Mass spectrum of p. Kp Lc + Mass plot 20

Lc +(2625) ○○ (4 S) data ▽▽ Continuum data Y / anti-Y ds/dxp(nb) Mass spectrum Lc +(2625) m li e r p ry a in Lc(2625)+ Lc(2595)+ Xp 21

Mass spectrum Lc+ p- decay processes Sc(2455)0 Exclude in analysis • Lc*(2595)+ Lc+ p+ p • Lc*(2625)+ Lc+ p+ p- Sc(2520)0 22

Cross sections Sc 0(2455) pre ry a n i lim ○○ (4 S) data ▽▽ Continuum data Y / anti-Y Sc 0(2520) m i l e pr ry a in 23

direct Lc and Sc production • Lc+ + c. c. (direct) = 189 ± 66 pb inclusive - (17. 9 ± 6. 0 pb ) x 3 Sc 0, +, ++(2455) + c. c. - (18. 8 ± 6. 4 pb) x 3 Sc 0, +, ++(2520) + c. c. - (31. 3 ± 10 pb) Lc+(2625) + c. c. = 47. 6 ± 16. 2 pb • Sc 0(2455) +c. c. (direct) = 17. 9 ± 6. 0 pb • Sc 0(2520) + c. c. (direct) = 18. 8 ± 6. 4 pb Λc(2595) and Λc(2775) feed down • Lc+(2625) + c. c. (direct) = 31. 3± 10 pb are included. 24

Ø Mass dependence strange ≠ charm not lie on the same line Ø Large discrepancy to ARGUS on L, and S* treatment of feed down? s/shad/(2 J+1) Result and discussion This work (very preliminary) ARGUS Ø Deviation of L(1520)[3/2 -] is not clear. Ø W < L, S, X W[sss] with “ “ no good diquark Previous Belle work Mass of baryons (Ge. V) 25

Results and discussion Prefer [3/2 -] or L=1? Why? Rate of L(1520)[3/2 -] is not large. Rates of Lc(2595)[1/2 -](L=1 state) and L(1405)[1/2 -] are “key”. s/shad/(2 J+1) Charmed baryons do not lie on “one” line. Jp : no measurement or not well measured quark-model prediction Lc > S c good diquark > bad diquark Large rate of Lc(2625)[3/2 -](L=1 state) Charmed baryons Lc(g. s)[1/2+] Lc(2625)[3/2 -] Wc Sc 0(2455)[1/2+] Sc 0(2520)[3/2+] Wc : no measurement of BR a plot with BR(0. 24+-0. 12%) by the phenomenological calculation. Production rate BR Very preliminary Sc(2800)[? ? ] use 3/2 Mass of baryons (Ge. V) 26

States On going L [1/2+] L(1405) [1/2 -] L(1520) [3/2 -] Lc + [1/2+] Lc(2595)+ [1/2 -] Lc(2625)+ [3/2 -] S [1/2+] S(1385) [3/2+] Sc(2455) [1/2+] Sc(2520) [3/2+] X [1/2+] X(1530) [3/2+] Xc Xc * [1/2+] W Wc Wc * [1/2+] [3/2+] Unknown J, BR 27

M(Xp) X(1530) Xc 28

s/shad/(2 J+1) Production rates Mass – Mass(g. s. ) [Ge. V/c 2] 29

Summary We measure production rates of strange and charmed baryons at s = 10. 52 Ge. V at Belle. “Systematic” study provides information on quark structure of hadrons. Configuration and performance of Belle detector is good for long-life particles like L, X, and W. We observed ‘charmed baryons do not lie on one line’. Can we explain by a diquark picture? Feed down processes Further study of many baryons with various spin-parity is interesting to see their quark structures. 30