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Production rate s of Strange and Charmed baryons at Belle

Production rate s of Strange and Charmed baryons at Belle. Nuclear physics consortium . string. @  s = 10.52 GeV. Production rate of hadrons. Production rate s/s had /(2J+1)  exp (- a m h ) due to linear potential. Slope of meson (qq bar ) is different from baryons (qqq).

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Production rate s of Strange and Charmed baryons at Belle

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  1. Production rates of Strange and Charmed baryons at Belle Nuclear physics consortium string @s = 10.52 GeV

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

  3. Previous data 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-] LEP s=92 GeV R.L.Jaffe, Phys.Rept.409:1-45,2005 ARGUS s=10.5 GeV s/shad/(2J+1) • Error bar in ARGUS is large • More precise data • No series of charmed baryon • First systematic measurement • of production rate for charmed • baryons. deviate Belle Mass of baryons (GeV)

  4. Diquark picture q • Interaction between quarks • Diquark correlations q Strange baryons (L[uds], S[uds]) mu, md ≈ ms(qqq) uniform q q q • Charmed baryon • (Lc[udc], Sc[udc]) • 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 • qq ( ) S=1 “bad” diquark Q

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

  6. 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, Lc* ,Sc ,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.

  7. Data of Belle Aerogel Cerenkov Time Of Flight CsI calorimeter S.C. solenoid 1.5T 3.5GeV e+ 8GeV e- Central Drift Chamber Silicon Vertex Detector KL μ system Integrated luminosity 79.366 fb-1 @s = 10.52 GeV 702.623 fb-1 @ s = 10.58 GeVϒ(4S)

  8. Good vertex reconstruction Profile of interaction point (IP) SSD placed in 3cm/2cm 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.

  9. momentum vectorof L Hyperon reconstruction p- • Decay processes • X-  Lp- • W-  LK- • Wc0  W-p+ • Decay processes • L  p p- • S0  Lg • S*(1385)+  Lp+ p IP Interaction point p p- Dx L ct = 7.89cm ct=7.89cm X-/W- ct= 4.91cm / 2.64cm p- IP p+or g (S0) (S*+) p+ for Wc0

  10. L ds/dxp L / Lbar preliminary Mass spectrum of L Xp Scaled momentum, xp = pc.m. / pc.m. : momentum of baryons s : beam total energy M : mass of baryons “Inclusive” total cross section Feed down processes from higher states L + Lbar = 373.9 ± 0.5 pb

  11. Mass spectra S0(1192)  Lg(BR~100%)S*(1383)+Lp+(BR=87%) real data events in 0.3 < xp <0.4 real data events in 0.3 < xp <0.4

  12. “Inclusive” cross sections vs. xp S0 +c.c. S*+ +c.c. ds/dxp ds/dxp preliminary Xp Xp Inclusive total cross section Inclusive total cross section S0 + S0 = 97.0 ± 1.5 pb S* + S* = 33.2 ± 2.4 pb

  13. 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) -23.6 8.0pb

  14. direct S0 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 pbS*+ + c.c. (inclusive) - 0.4 ± 0.06 pbL(1520) + c.c. = 32.8 ± 2.4 pb

  15. L(1520) Select p and K- from IP with cuts for distance from IP ○○(4S) data ▽▽Continuum data Y / anti-Y Mass spectrum of L(1520) preliminary L(1520)pK- BR=22.5%

  16. Direct cross section L(1520) L(1520)+c.c. (direct) = 15.3 ± 0.5 pb inclusive – 0.34 ± 0.17 pb Lc+ = 15.0 ± 0.26 pb

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

  18. Cross sections ofX andW X / X W / W ●●＠10.58, (4S) data ○○　＠10.52, Continuum data Y / anti-Y preliminary X + Xbar inclusive cross section = 25.55 +- 0.64 pb W + Wbar inclusive cross section = 1.15 +- 0.32 pb

  19. Wc  W-p+ +c.c. Counts Event rate / Lint. preliminary xp Mass [GeV] BR 1.25±0.5% for W-X 0.25±0.12% for W-p+ by phenomenological calculation (ref. PDG) s x BR (W-p+) + c.c. = 0.04 0.003 pb Wc  W-X = 0.2 pb

  20. Lc+, Lc*+,Sc0, and Sc*0 • Decay process analyzed in this work • Lc+  pK-p+ • Lc*(2625) Lc+p+p- • Sc0  Lc+ p- • Sc*(2520)  Lc+ p- +c.c. Mass spectrum ofpKp Lc+ Mass plot

  21. Lc+(2625) ○○(4S) data ▽▽Continuum data Y / anti-Y Mass spectrum preliminary ds/dxp(nb) Lc+(2625) Lc(2625)+ Lc(2595)+ Xp

  22. 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

  23. Cross sections ○○(4S) data ▽▽Continuum data Y/ anti-Y preliminary preliminary Sc0(2455) Sc0(2520)

  24. direct Lc and Sc production • Lc+ + c.c. (direct) = 189 ± 66 pb inclusive - (17.9 ± 6.0 pb ) x 3 Sc0,+,++(2455) + c.c. • - (18.8 ± 6.4 pb) x 3 Sc0,+,++(2520) + c.c. • - (31.3 ± 10 pb) Lc+(2625) + c.c. • = 47.6 ± 16.2 pb • Sc0(2455) +c.c. (direct) = 17.9 ± 6.0 pb • Sc0(2520) + c.c. (direct) = 18.8 ± 6.4 pb • Lc+(2625) + c.c. (direct) = 31.3± 10 pb Λc(2595) and Λc(2775) feed down are included.

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

  26. Results and discussion • Charmed baryons do not lie on “one” line. • Jp : no measurement or not well measured • quark-model prediction • Lc > Sc •  good diquark > bad diquark • Large rate of Lc(2625)[3/2-](L=1 state) • 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”. • Wc : no measurement of BR • a plot with BR(0.24+-0.12%) • by the phenomenological calculation. • Production rate  BR Charmed baryons Lc(g.s)[1/2+] s/shad/(2J+1) Lc(2625)[3/2-] Wc Sc0(2455)[1/2+] Sc0(2520)[3/2+] Sc(2800)[??] use 3/2 Very preliminary Mass of baryons (GeV)

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

  28. M(Xp) X(1530) Xc

  29. Production rates s/shad/(2J+1) Mass – Mass(g.s.) [GeV/c2]

  30. Summary • We measure production rates of strange and charmed baryons ats = 10.52 GeVat 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.

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