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Charm Decays at B Factories

Charm Decays at B Factories. Brian Meadows University of Cincinnati. Outline. Some results not covered in specific talks from Babar or Belle: Charm Baryons (mostly from BaBar) Charm Mesons – a few items Summary. BaBar and Belle. e + (3.5 GeV/c). e - (8 GeV/c).

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Charm Decays at B Factories

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  1. Charm Decays at B Factories Brian Meadows University of Cincinnati Brian Meadows, U. Cincinnati.

  2. Outline Some results not covered in specific talks from Babar or Belle: • Charm Baryons (mostly from BaBar) • Charm Mesons – a few items • Summary Brian Meadows, U. Cincinnati

  3. BaBar and Belle e+ (3.5 GeV/c) e- (8 GeV/c) Peak luminosity 1.081034 cm–2s–1 Integrated luminosity 363 fb–1 Peak luminosity 1.621034 cm–2s–1 Integrated luminosity 602 fb–1 • Main purpose: Study CP violation in asymmetric e+e- (4S)  BB • Both experiments have far exceeded their design goals • Approx. 1 ab-1 integrated flux combined Brian Meadows, U. Cincinnati

  4. Charm Hadrons at “B” Factories? • Cross sections are large Can use “off peak” data • Very high statistics (~1.4 x 106D’s / fb-1). • Also • Relatively small combinatorial backgrounds in e +e - interactions. • Good particle ID. • Detection of all possible final states including neutrals. • Good tracking and vertexing On Off ECM (GeV) Brian Meadows, U. Cincinnati

  5. Charm Baryons Brian Meadows, U. Cincinnati

  6. JP=1/2+ (L=0) JP=3/2+(L=0) Charm Isospin Strangeness JP=1/2+ (L=0) Charm Baryon States No JP are yet measured ! • |C| = 1: • L=0 Ground State – almost full: JP=1/2+: {6}qqSc(2455), Xc(2470), Wc(2698) All seen JP=1/2+: {3}qqLc(2285), X0c(2575) All seen JP=3/2+: {6}qqSc(2520), Xc(2645), ?? All but Wc* • L>1 – filling up ? JP=1/2-: – Lc(2593), Xc(2790), … JP=3/2-: – Lc(2625), Xc(2815), … • Several more new states from BaBar and Belle … and more … from CLEO 2 (or )c(2880), (or )c (2765) ?? Brian Meadows, U. Cincinnati

  7. 287fb-1hep-ex/0603052 New Baryon Lc(2940) • Observed in cc continuum production inD0pdecay mode(D0 K-p+, K-p+p-p+) Λc(2940)+ : M = (2939.8±1.3±1.0) MeV/c2 Γ = (17.5±5.2±5.9) MeV Λc(2880)+ Λc(2940)+ New data on Λc(2880)+ : New Decay Mode D0p BaBar: M = (2881.9±0.1±0.5) MeV/c2 Γ = (5.8±1.5±1.1) MeV PDG: (“Could be Sc”) M = (2880.9±2.3) MeV/c2 ; Γ < 8 MeV Wrong sign D0p D0 mass sidebands Brian Meadows, U. Cincinnati

  8. 287fb-1hep-ex/0603052 New Baryon Lc(2940) • Neither Lc(2940) nor Lc(2880) seen in D+p system  Neither seen as Sc++’s • Observations: • Why not seen in Lcp+p- or Scp? • Three states predicted near this mass3/2-, ½+, ½- • Lc(2940) is 6 MeV/c2 belowD*pthreshold • Lc(2940) ispmass aboveLc(2880) Brian Meadows, U. Cincinnati

  9. Phys.Lett.B628:18-24,2005 SELEX Search for cc States • Predicted in mass range 3.5 – 3.8 GeV/c2 • Predicted cross-sections from e+e- @ 10 GeV/c2 ~ 1-250 fb Double-charm cross-sections under-estimated by NRQCD  expect to produce 102 – 104 from 232 fb-1 SELEXreports state at 3.52 GeV/c2 - beam ~ 1,630 +c Not confirmed by FOCUS beam ~ 19,500 +c Nor BaBar e+e- ~ 600K c+ Brian Meadows, U. Cincinnati

  10. Λc+K–π+ p*> 0 GeV/c 232fb-1hep-ex/0605075 Λc+K–π+ p*>2.3 GeV/c Λc+K–π+π– p*> 0 GeV/c Λc+K–π+π– p*>2.3 GeV/c Search for cc States cc+(+)c+K-+(+) Search made throughout ranges indicated • for both charge states, • with and without p*cuts 21 two-d fits: Gaussian signal on background in overlapping 10 MeV/c2 ranges. Results normalized to cross-section for producing c+ 95% C.L. limits: Brian Meadows, U. Cincinnati

  11. Ξc0π+ p*> 0 GeV/c 232fb-1hep-ex/0605075 Ξc0π+ p*> 2 GeV/c Ξc0π+π+p*> 0 GeV/c Ξc0π+π+p*> 2 GeV/c Search for cc States 95% C.L. limits: c c+(+)Xc0+(+) Search made throughout ranges indicated 50 fits: Double Gaussian signal on linear background in 10 MeV/c2 ranges. Results compare with X ??? Brian Meadows, U. Cincinnati

  12. 462 fb-1PRELIMINARY Search for Xcc States • Belle also found no evidence for the state seen by SELEX using an even larger sample. M(Lc+K-p+) (GeV/c2) Brian Meadows, U. Cincinnati

  13. 462 fb-1 462 fb-1PRELIMINARY Observation of Two New Xc(csu)States in cc Continuum Production • While searching for weak decay of • Xcc Lc+K- p+ •  pK-p+ • Found strong decays of new Xc* ‘s instead: • Xcx Lc+K- p+ No structure in Lc+ sidebands Nor in Lc+K+p- or Lc+K-p- wrong sign combinations. Brian Meadows, U. Cincinnati

  14. Xc0W-K+ 116 fb-1 Preliminary 230 fb-1 Preliminary Wc0W-p+ The Spin of The W- • The existence of large samples of charm baryons makes possible what was once incredibly difficult ! Earlier results from bubble chambers using small, unaligned samples of W- could only conclude that J>1/2. Assume the spin of charmed parent is ½: In the charm hyperon rest frame, the W- is produced with helicity § ½ independent of the W- spin J. Brian Meadows, U. Cincinnati

  15. 230 fb-1 Preliminary 116 fb-1 Preliminary Xc0W-K+ Wc0W-p+ J = 1/2 J = 3/2 J = 3/2 J = 5/2 The Spin of The W- • The W-L K - decay distribution in its “helicity frame” is then  Conclude J = 3/2 (if charmed parents are J=1/2). Brian Meadows, U. Cincinnati

  16. 357 fb-1hep-ex/0511007 (2005) Extension to Charm Baryons? • Information on charm baryon spins can come from decays like B+,0c+c0,-  -+ • So far (357 fb-1) only ~12 events where c0 -+ • Not promising for determination of J Brian Meadows, U. Cincinnati

  17. 140 fb-1hep-ex/0409005 (2005) Three-Body Decays • BF’s about 10 x 2-body B-c+ p p - (product of BF’s ~ 2 x 10-5) have. significant # events: B- Sc0 p (Sc0  Lc+-) • Can treat its decay similarly to - c0(2455) c+- Brian Meadows, U. Cincinnati

  18. Charmed Mesons Brian Meadows, U. Cincinnati

  19. Heavy-Light Systems 2jq+1LJ  JP • Narrow statesare easy to find. • Two wide states are harder. • Since charm quark is not infinitely heavy, some jq=1/2, 3/2 mixing can occur between the two JP=1+ states. jq = 3/2 2+ small 3P2 D-wave large 1+ 1P1 S-wave L = 1 1+ 3P1 small D-wave jq = 1/2 1P0 0+ large S-wave tensor spin-orbit jq = 1/2 1- small 1S1 L = 0 small 0- 1S0 Expected by quark models To be below D(*)K threshold Brian Meadows, U. Cincinnati

  20. hep-ex/0507030 281 fb-1   D* D K0 DsJ Mixing in JP = 1+DsJ(2460)/Ds1(2536) ? • Belle has analyzed Ds1(2536) decays to D*K to look for an S-wave component. • (In the limit the c quark has infinite mass, the narrow states would decay in pure D-wave) • Angular distribution of + in D*+ system leads to the limits: 0.277 < S/(S+D) < 0.955 Indicative of some S-wave NEW mode: D+s1D*+K0 1 + A cos2 : S-wave: A=0 P-wave: A=3 A = -0.70 § 0.03 Brian Meadows, U. Cincinnati

  21. 232fb-1hep-ex/0604030 DsJ’s - Overtly Exotic ? • No indication of overtly exotic charge states Circles are Ds side-bands DsJ(2317) ? DsJ(2460) ? Ds+p- Ds+p+ . Brian Meadows, U. Cincinnati

  22. 350 fb-1 hep-ex/0507064 PRL 93, 181801 113 fb-1 Decays of B0 Ds(DsJ )+ +h- • Exotic nature of DsJ states could show up in • B 0 Ds(J)K - is especially interesting none of the final state quarks (cuss) are in the initial B (bd) meson. • Expect Rh ~ 1 for cs and Rh ~ 0.1 for csuu C.-H. Chen, H.-n Li, Phys. Rev. D 69, 054002 (2004)  R_{K} ~ R_{D} ~ 1 (no clear evidence for csdd) Brian Meadows, U. Cincinnati

  23. Decays normalized to K-p+p+ D+p+p0 D+K+p0 124fb-1hep-ex/0605044 Doubly Cabbibo Suppressed Decays First measurement of (CLEO 1990 < 0.04%) Measured rate relative to D+K-++ then used average of PDG and recent CLEO measurement for this rate. Uncertainty in D+K-p+p+ Brian Meadows, U. Cincinnati

  24. s c u c d d u d d s s u u c c d d d u Doubly Cabbibo Suppressed Decays Exact SU(3): BaBar:2/(1.49 § 0.29) • Also: BaBar:0.70 § 0.17 SU(3) predictions are over-simplified: • First ratio affected by Ks-KL interference • D+  K+0 can also proceed by W-exchange or annihilation diagrams.  Measurements are challenging Results still not well understood. d Brian Meadows, U. Cincinnati

  25. 229fb-1PRELIMINARY K+ 3 K+ 2 281 fb-1 hep-ex/0507071 PRELIMINARY  M (MeV/c2) Wrong Sign D0 Decays Despite high backgrounds, measurements at few % level (BaBar tags other side) • Time-integrated rates can be compared with tan4c = 0.281 § 0.006 % • Belle/BaBar agreement excellent • big improvement over PDG values • D* tagging allows measurement of CP asymmetries Belle: K+2 -0.00 6§ 0.053; K+3 -0.018§ 0.044 consistent with zero.  any new physics at level much smaller than DCS for “wrong sign” decays. Before After K+ 2 M (MeV/c2) Brian Meadows, U. Cincinnati

  26. 90.4fb-1hep-ex/0508039 D0*D00 D0*D0 Ds*Ds0 Ds*Ds M(K+K-+)-M(K+K-+) M(K+K-+0)-M(K+K-+) M(K+K-+)-M(K+K-+) M(K+K-+0)-M(K+K-+) GeV/c2 (D(s)*D(s)0)/(D(s)*D(s)) • BaBar has improved measurements of the 0/ ratios: Agree with current results Fresh input to PT Lost g Brian Meadows, U. Cincinnati

  27. Summary • B Factories provide a very clean environment for the production of charm hadrons  new particle paradise ! • Large (and growing) samples of charm mesons and baryons are likely to complement results from -charm facilities for some time to come • In several ways, we are learning how information on systems to which charm hadrons, or B mesons decay can be extracted • There is a large and enthusiastic community anxious to work on all aspects of the physics available. Brian Meadows, U. Cincinnati

  28. Back up Slides Brian Meadows, U. Cincinnati

  29. hep-ex/0507009 232 fb-1 Precision Measurement of c Mass • Important measurement • most charm baryon masses measured relative to this • Method: • Choose decay modes with small Q-value/large BR: c K+Ks0and0K+Ks0 • Estimate / adjust major systematic uncertainties in: • Material audit – determine  and K0 mass vs. decay path length • Magnetic field – determine  and K0 mass vs. momentum in lab. • Much larger control samples: • c+ pK-+ 1.5 x 106 evs. • c+  pK0 2.4 x 105 evs. Q = 177.8 MeV/c2 4627§ 84 events Q = 100.9 MeV/c2 264§ 20 events Brian Meadows, U. Cincinnati

  30. Combined measurement : m(Lc) = 2286.46  0.14 MeV/c2 hep-ex/0507009 232 fb-1 Results Large Q • Most precise measurement of charm mass to date • Approximately 4 x more precise than Current PDG value: 2284.9 § 0.6 MeV/c2 and about 2.5  higher Brian Meadows, U. Cincinnati

  31. PDG 2005 Charm Baryon States • L>1 – filling up ? JP=1/2-: – Lc(2593), Xc(2790), … JP=3/2-: – Lc(2625), Xc(2815), … • Most massive in PDG 2005 is c (2815) CLEO 2 has added c(2880) and c(2765) D*p Dp Brian Meadows, U. Cincinnati

  32. 281 fb-1PRL94, 122002 (2005) New Sc (2800) Triplet Lc pK-p+ sidebands Could be JP = 3/2-Sc2 ?? Brian Meadows, U. Cincinnati

  33. Charmed Meson Spectroscopy pre 2003 D*0K+threshold D0K+threshold BABAR/CLEO may have found these – but below threshold. Brian Meadows, U. Cincinnati

  34. Charmed Meson Spectroscopy Now John Bartelt, Sept, 2003 Brian Meadows, U. Cincinnati

  35. No indication of neutral or doubly-charged partner near 2317 MeV  I=0 DsJ*(2317)+Ds+0 BABAR: 232 fb-1 Submitted to PRD N=3180±80 Preliminary Ds*(2112) signal Preliminary Ds*(2112) reflection Dark shade: DsJ(2460) reflection Circles: Ds sidebands Brian Meadows, U. Cincinnati

  36. 232fb-1hep-ex/0604030 Update on Charmed-StrangeMesons DsJ*(2317)+ and DsJ(2460)+ • New, comprehensive study of decays to Ds+ plus one or two ±, 0, or ’s Decay pattern if JP=0+ and JP=1+, respectively Ds+0 only decay mode observed for DsJ*(2317)+ NB: all “Seen” modes are also “Allowed” Brian Meadows, U. Cincinnati

  37. 232fb-1hep-ex/0604030 DsJ* Update: • From DsJ*(2317)+Ds+0 : • From DsJ*(2460)+Ds+, Ds+0: • New from Ds++- : No indication of DsJ*(2317)+ Ds++- New mode: DsJ*(2536)+ Ds++- Brian Meadows, U. Cincinnati

  38. 211fb-1hep-ex/0605036 B Decays - Absolute Branching Fractions • BB sample with one B fully reconstructed decays of the other BD(*)+,0 X • Observe Ds+ and DsJ(2460) signals in the recoil mass, mX •  absolute BF’s for Ds+ ( +) and for DsJ*(2460)+ p e- D* Breco e+ Bsignal D* X Brian Meadows, U. Cincinnati

  39. PDG: (4.3 § 1.2) % 211fb-1hep-ex/0605036 113fb-1PRL 93, 181801 (2004) DsJ(2460)+ Absolute BFs, cont. • For the Ds+ signal: • Combine with previous measurements to obtainabsolute BFs: • Sum of known BFs: 0.76±0.20 (Ds*+ Ds+) Is there another mode? Brian Meadows, U. Cincinnati

  40. 0 BD DsJ*(2317)+,DsJ*(2317)+Ds+0 Belle: 274M BB BELLE-CONF- 0461 (2004) • DsJ*(2317) decay mode  natural spin-parity • DsJ*(2317) decay angular distribution  spin 0 Dotted line: J = 1 2/d.o.f = 38/8 Natural spin- parity  JP = 0+ Solid line: J = 0 2/d.o.f = 3/8 Brian Meadows, U. Cincinnati

  41. DsJ(2460)+Ds+  / Ds*(2112)+0 Ds*+Ds+ DsJ(2460)+Ds+ Preliminary Preliminary N=560±40 Open points: Ds sidebands Light shade: Ds*(2112) reflection Dark shade: DsJ*(2317) reflection N=920±60 Open points: Ds sidebands BABAR: 232 fb-1 Submitted to PRD Brian Meadows, U. Cincinnati Preliminary

  42. Belle: 274M BB BELLE-CONF-0461 (2004) BDDsJ(2460)+ (b): DsJ(2460)+Ds+ (c): DsJ(2460)+Ds *(2112) +0 Ds*+ Ds+ No Ds  decay for J=0 Ds*0 Dashed line: J = 2 2/d.o.f = 89/8 Solid line: J = 1 S-wave Solid line: J = 1 2/d.o.f = 4/8 JP = 1+ Brian Meadows, U. Cincinnati cos(Ds*0)

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