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Topics in charm hadron studies at Belle

Topics in charm hadron studies at Belle. B. Golob University of Ljubljana Belle Collaboration. Outline Introduction B-factory = charm-factory 2. New spectroscopy Exotic / non-exotic ? 3. D 0 -D 0 mixing Last man standing 4. Outlook. B. Golob, Belle.

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Topics in charm hadron studies at Belle

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  1. Topics in charm hadron studies at Belle B. Golob University of Ljubljana Belle Collaboration • Outline • Introduction • B-factory = charm-factory • 2. New spectroscopy • Exotic/non-exotic? • 3.D0-D0 mixing • Last man standing • 4. Outlook B. Golob, Belle Topics in charm hadron studies at Belle 1 Particle Physics Seminar, UCL

  2. Introduction Mt. Tsukuba Belle KEKB Belle 8 GeV e- ~1 km in diameter 3.5 GeV e+ Mar. 2003 Oct. 2006 Continuous injection, peak luminosity: L = 16.5 nb-1 s-1 Integrated luminosity: Ldt  700 fb-1 B. Golob, Belle Topics in charm hadron studies at Belle 2 Particle Physics Seminar, UCL

  3. B (bu, bd) BB pair production U(4s) B (bu, bd) s(b b)  1.1 nb (~750·106 BB pairs) B B at rest in CMS system; asymmetric collider → measurable decay dist.; numerous measurements in field of CPV in B system g* c distinct kinematics and topology w.r.t. B B s(c c)  1.3 nb (~850·106 XcYc pairs) + light qq production c Introduction conted √s = M(U(4S))c2 continuum production jets of hadrons Last years renewed efforts in charm studies Charm is... a way of getting the answer yes without having asked any clear question. A. Camus (1913 - 1960) B. Golob, Belle Topics in charm hadron studies at Belle 3 Particle Physics Seminar, UCL

  4. Introduction conted Central Drift Chamber e+ 3.5 GeV 3(4) layer Si det. e- 8 GeV Aerogel Cherenkov (n=1.015- 1.030) m and KL Counter (14/15 layers RPC+Fe) 1.5T SC solenoid EM calorimeter CsI (16X0) tracking s(pt)/pt= 0.2% √(pt2+2.5) PID e(K±) ~ 85%e(p±→K±)  10% for p < 3.5 GeV/c B. Golob, Belle Topics in charm hadron studies at Belle 4 Particle Physics Seminar, UCL

  5. aEM as J=1/2 J=3/2 L=0 E New spectroscopy non-exotic states baryons: q1q2q3 qi=u,d,s,c C (c: +1) I3 (u: +1/2; d: -1/2) need to use non-perturbative QCD experimental results on baryons testing ground for QCD models S (s: -1) baryons with C>1 not yet observed, except of single exp. claim B. Golob, Belle Topics in charm hadron studies at Belle 5 Particle Physics Seminar, UCL

  6. u p+ d c p s K- Lc+ K- Xcc+ u c c u d p+ d New spectroscopy non-exotic states, conted Selex, PRL89, 112001 (2002) M=3519±1 MeV/c2 Minv(Lc+ K-p+) Belle measurement with higher stat. (and bkg.) PRL97, 162001 (2006) 460 fb-1 fit with bkg.+ possible signal p*(Lc+)>2.5 GeV (Lc from continuum) production mechanism? B. Golob, Belle Topics in charm hadron studies at Belle 6 Particle Physics Seminar, UCL

  7. PRL97, 162001 (2006) 460 fb-1 p Lc+ K- s s K- u u p+ Xc+ d d u u c p+ c New spectroscopy non-exotic states, conted ...Life is like a box of chocolates, you never know...: Forrest Gump (1994) 405 ± 50 evts sigificance 5.7s 326 ± 40 evts sigificance 9.2s Wrong sign charge comb.: Lc+ K+p- possible reflections from Lc*+→ Lc+p+ p- with p misidentified as K would appear here Right sign charge comb.: Lc+ K-p+ most plausible interpretation: strong decay of excited (L>0) Xc+ Xc+ isospin dublet  Xc0(ddc)? B. Golob, Belle Topics in charm hadron studies at Belle 7 Particle Physics Seminar, UCL

  8. PRL97, 162001 (2006) 460 fb-1 67 ± 20 evts sigificance 4.4s New spectroscopy non-exotic states, conted Neutral state first observation of two isodublets of excited (L>0) Xc+ p*(Lc+)>3.5 GeV (higher bkg.) confirmed by BaBar questions: M, G of Xc(2980)+ (2-3s difference with BaBar) JP assignments Right sign charge comb.: Lc+ KSp- BaBar, hep-ex/0607042 systematics from different bkg. and signal parameterization B. Golob, Belle Topics in charm hadron studies at Belle 8 Particle Physics Seminar, UCL

  9. PRL91, 262001 (2003) 152M BB signal B ECM/2 ECM/2 U(4s) e+ e- B ∑ pi, ∑ Ei New spectroscopy exotic states Y(2S) should be “exotic ?”; nature not known (yet) If you search deep enough you can find rare exotic treasures. Christina Aguilera (b. 1980) X(3872)most prominent observed by Belle B±→ K±p+p-J/y Reconstruction of B decays signal B. Golob, Belle Topics in charm hadron studies at Belle 9 Particle Physics Seminar, UCL

  10. PRL91, 262001 (2003) 152M BB cc spectrum c b Y(2S) c B s K cc2’ u, d u, d y” y’ hc’ hc hep-ex/0505038 275M BB cc1 cc0 J/y hc M(p+p-J/y) New spectroscopy exotic states conted X(3872) prod. and decay similar to cc Mass M=3871.9±0.5 MeV/c2 (average) intriguing: M - M(D0) - M(D*0) = 0.6 ±0.9MeV/c2 MD+MD* B. Golob, Belle Topics in charm hadron studies at Belle 10 Particle Physics Seminar, UCL

  11. hep-ex/0505037, 275M BB New spectroscopy exotic states conted no. of B’s (Mbc, DE) in bins of M(gJ/y) Possible JPC C parity B±,0 → K±,0X (→gJ/y) C(X(3872))=+1 B±,0 → K±,0X (→r(p+ p-)J/y) P=+1 (L=0) favoured 13.6 ± 4.4 evts. (4s) L=0,c2/ndf=43/39 L=1,c2/ndf=71/39 DE side band B. Golob, Belle Topics in charm hadron studies at Belle 11 Particle Physics Seminar, UCL

  12. hep-ex/0505038, 275M BB cc JPC p+ X(J/y, r) q l- l+ JPC=1++ p- p- X(J/y, r) q B |cos(q)| K p+ New spectroscopy exotic states conted JPC=0++ c2/ndf=31/9 Angular distributions B±,0 → K±,0X (→ p+ p-J/y) examples shown |cos(q)| all J=0, 1, 2 disfavoured except J=1++, 2++ also 2-+?, detailed study of M(pp): CDF, PRL96, 102002 (2006) c2/ndf=5/9 X→D0D0p0 ? 1++ →DD*: L=0 2++ →DD*: L=2, suppressed by (q*)2L+1 B. Golob, Belle Topics in charm hadron studies at Belle 12 Particle Physics Seminar, UCL

  13. PRL97, 162021 (2006) 455M BB B±,0 → K±,0X (→ D0 D0p0) Q DE D0 D*0 and D0 D0p0 indistinguishable New spectroscopy exotic states conted several D0 decay modes 2-d (Q, DE) unbinned lnL fit Nsig=23.4±5.6 6.4 s M=(3875.2±0.7±0.31.6±0.8) MeV/c2 p0 reconstr. hard to accommodate by 2++ state if X(3872): JPC=1++ B. Golob, Belle Topics in charm hadron studies at Belle 13 Particle Physics Seminar, UCL

  14. cc 1++cc1’ cc 2-+ not quite excluded New spectroscopy exotic states conted Remaining states ~O(102)lower than prediction Molecule model E.S.Swanson,PLB588,189(2004) almost all properties in agreement with DD* molecule model but... ..should be.. ~0.08 further theoretical wisdom: large mixing between cc1’ and X(3872) It is characteristic of wisdom not to do desperate things. H.D. Thoreau (1817 - 1862) B. Golob, Belle Topics in charm hadron studies at Belle 14 Particle Physics Seminar, UCL

  15. New spectroscopy conted Other charm related spectroscopic results PRL97, 162001 PRL94, 122002 Lc(2880) Sc(2800) DsJ(2715) Xc(3077) Xc(2980) PRL97, 162001 hep-ex/0608043 hep-ex/0608031 X(3940) hep-ex/0507019 X(3872) Y(3940) Y(4260) PRL94, 182002 Z(3930) PRL96, 082003 hep-ex/0505037 hep-ex/0612006 hep-ex/0505038 PRL91, 262001 PRL97, 162021 B. Golob, Belle Topics in charm hadron studies at Belle 15 Particle Physics Seminar, UCL

  16. Vuj* Vci* Vcj Vui u c W+ u c D0 D0 d, s, b d, s, b d, s, b d, s, b D0 W- W+ D0 W- c u u c if mi = mj  due to CKM unitarity: no D0 D0 mixing D0-D0Mixing Phenomena neutral meson can change into antiparticle; box Feynman diagram History K0’s Bd0’s Bs0’s mixing exp. verified CDF, hep-ex/0609040 D0 case the only system with down q’s in loop the only system with unobserved mixing up to date |Vcb*Vub|<< |Vcs*Vus|, |Vcd*Vud| mainly d,s contrib.; md ~ ms mixing small B. Golob, Belle Topics in charm hadron studies at Belle 16 Particle Physics Seminar, UCL

  17. D0-D0 Mixing conted Phenomenology two mass eigenstates, linear superpos. of weak eigenstates rare process, appropriate for NP search; caveat: SM contribution not well known Don't keep mixing in these other things. It only confuses. SM predictions x,y  10-3 - 10-2 K. Kinski (1926 - 1991) B. Golob, Belle Topics in charm hadron studies at Belle 17 Particle Physics Seminar, UCL

  18. PRD72, 071101 (2005), 253 fb-1 right sign (RS) Semileptonic decays DM from pmiss with constraints • Wrong charge combinations (WS): • D*+→ D0pslow+D0 → D0 → K(*)+e-n • flavour tag at prod. • no “DCS” decays  NWS/NRS = RM (x2+y2)/2 • Observable: • DM = M(Kenpslow) - M(Ken) • good resol., bkg. rejection • Reconstruct n: • pmiss = pCMS – pKep – prest • M(Kenpslow)  M(D*+), M2(n)  0 DM from pmiss FWHM 55→7 MeV NRS = (229.45 ± 0.69) ·103 B. Golob, Belle Topics in charm hadron studies at Belle 18 Particle Physics Seminar, UCL

  19. PRD72, 071101 (2005), 253 fb-1 Semileptonic decays conted • Reduce bkg., increase sensitivity: • <t >(bkg., RS) < <t >(mix. signal) • 6 bins in 1 < t < 10 RM = (0.20 ± 0.47 ± 0.14) ·10-3 RM < 1.2 · 10-3 95% C.L. dominating systematics from limited bkg. statistics (embedded pslow) B. Golob, Belle Topics in charm hadron studies at Belle 19 Particle Physics Seminar, UCL

  20. PRL96, 151801 (2006), 400 fb-1 D*+→ D0pslow+D0 → D0 → K+p- Hadronic decays K+p- 3s Q interval Wrong charge combinations (WS): WS DCS decays  interference 3s M interval • Observables: • M=M(Kp) • Q = M(K p pslow) - M(Kp) - M(p) • 2D M-Q fit: WS NWS = 4024 ± 88 B. Golob, Belle Topics in charm hadron studies at Belle 20 Particle Physics Seminar, UCL

  21. PRL96, 151801 (2006), 400 fb-1 Hadronic decays K+p- conted M, Q, st depent signal fractions used in decay time fit (WS): (RS decay time) largest bkg. random pslow same resol. f. as signal t(D0) = 409.9 ± 0.7 fs toy MC: no bias x’2, y’, RD free parameters B. Golob, Belle Topics in charm hadron studies at Belle 21 Particle Physics Seminar, UCL

  22. PRL96, 151801 (2006), 400 fb-1 x’2 < 0.72 ·10-3 -0.99% < y’ < 0.68% no signif. CPV Hadronic decays K+p- conted 95% C.L. (x’2, y’) contour frequentist, FC ordering Results: RD = (3.64 ± 0.17 ) ·10-3 x’2 = (0.18 ±0.210.23) · 10-3 y’= (0.6 ±4.03.9) · 10-3 AD = (23 ± 47) ·10-3 AM = (670 ± 1200) ·10-3 no CPV CPV • CPV allowed: • separate D0 and D0 tags • (x’2,y’,RD) → (x’±2, y’±,RD±) (0,0) lies on 96.1% C.L. contour largest syst. due to p*(D*) selection B. Golob, Belle Topics in charm hadron studies at Belle 22 Particle Physics Seminar, UCL

  23. PRL96, 151801 (2006), 400 fb-1 y [10-2] 2 1 1 2 x [10-2] Hadronic decays K+p- conted (x, y) plane: d 0o ± 70o Cleo-c, hep-ex/0607078, 281pb-1 RM 0.4·10-3 @ 95% C.L. For my part I know nothing with any certainty, but the sight of the stars makes me dream. V. van Gogh (1853 - 1890) B. Golob, Belle Topics in charm hadron studies at Belle 23 Particle Physics Seminar, UCL

  24. A. Petrov, hep-ph/0311371 Outlook • Mixing and CPV searches: • no evidence so far • semil. decays: RM < 1.2 · 10-3 95% C.L. • decays to K+p-: RM < 0.4 · 10-3 95% C.L. • most stringent limits on mixing paramers to date • decays to K+ np: precise WS rate measent PRD72, 071101 (2005), 253 fb-1 PRL96, 151801 (2006), 400 fb-1 PRL95, 231801 (2005), 280 fb-1 B. Golob, Belle Topics in charm hadron studies at Belle 24 Particle Physics Seminar, UCL

  25. Outlook New measurements under way: BaBar+Belle 2 ab-1, charm fact. 20 fb-1 allowed excluded ~95% C.L. d 0o ± 25o K+p- meas. KSpp t-dependent Dalitz & K+K-/p+p- 2 y[10-2] 2 y[10-2] 1 1 1 x[10-2] x[10-2] B. Golob, Belle Topics in charm hadron studies at Belle 25 Particle Physics Seminar, UCL

  26. Summary • B factories are producing charm hadrons in abundance; in many aspects competitive and complementary to charm factories (Cleo-c, BES) • Increased interest in charm physics in recent years • Several new (expected - understood/unexpected - non-understood) states observed; can serve as testing ground for better understanding of QCD • Rare processes - mixing - are exploited to search for unknown phenomena (NP); need better theoretical understanding, but first need to be observed Prediction is very difficult, especially of the future. N. Bohr (1885 - 1962) B. Golob, Belle Topics in charm hadron studies at Belle 26 Particle Physics Seminar, UCL

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