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B. Golob, BelleTopics in charm hadron studies at Belle 1Particle Physics Seminar, UCL B. Golob University of Ljubljana Belle Collaboration Outline 1.Introduction.

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Presentation on theme: "B. Golob, BelleTopics in charm hadron studies at Belle 1Particle Physics Seminar, UCL B. Golob University of Ljubljana Belle Collaboration Outline 1.Introduction."— Presentation transcript:

1 B. Golob, BelleTopics in charm hadron studies at Belle 1Particle Physics Seminar, UCL B. Golob University of Ljubljana Belle Collaboration Outline 1.Introduction B-factory = charm-factory 2. New spectroscopy Exotic/non-exotic? 3. D 0 -D 0 mixing Last man standing 4. Outlook Topics in charm hadron studies at Belle

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

3 Introduction cont ed B. Golob, BelleTopics in charm hadron studies at Belle 3Particle Physics Seminar, UCL s = M( (4S))c 2 (4s) B (bu, bd) (b b) 1.1 nb (~750·10 6 BB pairs) B B at rest in CMS system; asymmetric collider measurable decay dist.; numerous measurements in field of CPV in B system * c c Last years renewed efforts in charm studies (c c) 1.3 nb (~850·10 6 X c Y c pairs) + light qq production distinct kinematics and topology w.r.t. B B jets of hadrons continuum production BB pair production Charm is... a way of getting the answer yes without having asked any clear question. A. Camus (1913 - 1960)

4 3(4) layer Si det. Central Drift Chamber Aerogel Cherenkov (n=1.015- 1.030) 1.5T SC solenoid e - 8 GeV e + 3.5 GeV EM calorimeter CsI (16X 0 ) and K L Counter (14/15 layers RPC+Fe) tracking (p t )/p t = 0.2% (p t 2 +2.5) PID (K ± ) ~ 85% ( ±K ± ) 10% for p < 3.5 GeV/c Introduction cont ed B. Golob, BelleTopics in charm hadron studies at Belle 4Particle Physics Seminar, UCL

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

6 New spectroscopy non-exotic states, cont ed B. Golob, BelleTopics in charm hadron studies at Belle 6Particle Physics Seminar, UCL c c d u d u u d c + K-K- s cc + c + K-K- p + Selex, PRL89, 112001 (2002) M inv ( c + K - + ) Belle measurement with higher stat. (and bkg.) PRL97, 162001 (2006) 460 fb -1 p*( c + )>2.5 GeV ( c from continuum) fit with bkg.+ possible signal production mechanism? M=3519±1 MeV/c 2

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

8 New spectroscopy non-exotic states, cont ed B. Golob, BelleTopics in charm hadron studies at Belle 8Particle Physics Seminar, UCL Right sign charge comb.: c + K S - 67 ± 20 evts sigificance 4.4 p*( c + )>3.5 GeV (higher bkg.) StateMass [MeV/c 2 ]Width [MeV/c 2 ] c (2980) + 2978.5±2.1±2.043.5±7.5±7.0 c (3077) + 3076.7±0.9±0.56.2±1.2±0.8 c (2980) 0 3082.8±1.8±1.55.2±3.1±1.8 confirmed by BaBar questions: M, of c (2980) + (2-3 difference with BaBar) J P assignments BaBar, hep-ex/0607042 first observation of two isodublets of excited (L>0) c + systematics from different bkg. and signal parameterization Neutral state PRL97, 162001 (2006) 460 fb -1

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

10 New spectroscopy exotic states cont ed B. Golob, BelleTopics in charm hadron studies at Belle 10Particle Physics Seminar, UCL b c c s u, d (2S) B K X(3872) prod. and decay similar to cc c J/ c c0 c1 c2 hchc cc spectrum M D +M D* Mass M=3871.9±0.5 MeV/c 2 (average) intriguing: M - M(D 0 ) - M(D* 0 ) = 0.6 ± 0.9 MeV/c 2 PRL91, 262001 (2003) 152M BB M( + - J/ ) hep-ex/0505038 275M BB

11 New spectroscopy exotic states cont ed B. Golob, BelleTopics in charm hadron studies at Belle 11Particle Physics Seminar, UCL hep-ex/0505037, 275M BB Possible J PC C parity B ±,0 K ±,0 X ( J/ ) no. of Bs (M bc, E) in bins of M( J/ ) 13.6 ± 4.4 evts. (4 ) C(X(3872))=+1 B ±,0 K ±,0 X ( ( + - ) J/ ) L=0, 2 /ndf=43/39 L=1, 2 /ndf=71/39 P=+1 (L=0) favoured E side band

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

13 New spectroscopy exotic states cont ed B. Golob, BelleTopics in charm hadron studies at Belle 13Particle Physics Seminar, UCL B ±,0 K ±,0 X ( D 0 D 0 0 ) D 0 D* 0 and D 0 D 0 0 indistinguishable PRL97, 162021 (2006) 455M BB several D 0 decay modes 2-d (Q, E) unbinned ln L fit N sig =23.4±5.6 6.4 M=(3875.2 ±0.7± 0.3 1.6 ±0.8) MeV/c 2 0 reconstr. E Q if X(3872): hard to accommodate by 2 ++ state J PC =1 ++

14 New spectroscopy exotic states cont ed B. Golob, BelleTopics in charm hadron studies at Belle 14Particle Physics Seminar, UCL Remaining states ~ O (10 2 )lower than prediction almost all properties in agreement with DD* molecule model but... cc 2 -+ not quite excluded E.S.Swanson,PLB588,189(2004) cc 1 ++ c1 Molecule model..should be.. ~0.08 further theoretical wisdom: large mixing between c1 and X(3872) It is characteristic of wisdom not to do desperate things. H.D. Thoreau (1817 - 1862)

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

16 Phenomena D 0 -D 0 Mixing c u u c d, s, b W+W+ W-W- D0D0 D0D0 neutral meson can change into antiparticle; box Feynman diagram History if m i = m j due to CKM unitarity: no D 0 D 0 mixing |V cb *V ub |<< |V cs *V us |, |V cd *V ud | mainly d,s contrib.; m d ~ m s mixing small K0sBd0sBs0sK0sBd0sBs0s mixing exp. verified CDF, hep-ex/0609040 D 0 case the only system with down qs in loop the only system with unobserved mixing up to date c u u c d, s, b W+W+ W-W- D0D0 D0D0 V ci * V cj V uj * V ui B. Golob, BelleTopics in charm hadron studies at Belle 16Particle Physics Seminar, UCL

17 D 0 -D 0 Mixing cont ed Phenomenology two mass eigenstates, linear superpos. of weak eigenstates B. Golob, BelleTopics in charm hadron studies at Belle 17Particle Physics Seminar, UCL SM predictions x,y 10 -3 - 10 -2 rare process, appropriate for NP search; caveat: SM contribution not well known Don't keep mixing in these other things. It only confuses. K. Kinski (1926 - 1991)

18 Wrong charge combinations (WS): D* + D 0 slow + D 0 D 0 K ( * )+ e - flavour tag at prod. no DCS decays N WS /N RS = R M (x 2 +y 2 )/2 Observable: M = M(Ke slow ) - M(Ke ) good resol., bkg. rejection Reconstruct : p miss = p CMS – p Ke – p rest M(Ke slow ) M(D* + ), M 2 ( ) 0 PRD72, 071101 (2005), 253 fb -1 M from p miss M from p miss with constraints right sign (RS) N RS = (229.45 ± 0.69) ·10 3 Semileptonic decays FWHM 557 MeV B. Golob, BelleTopics in charm hadron studies at Belle 18Particle Physics Seminar, UCL

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

20 PRL96, 151801 (2006), 400 fb -1 Hadronic decays K + - D* + D 0 slow + D 0 D 0 K + - DCS decays interference Wrong charge combinations (WS): Observables: M= M(K ) Q = M(K slow ) - M(K ) - M( ) 2D M-Q fit: N WS = 4024 ± 88 3 Q interval 3 M interval WS B. Golob, BelleTopics in charm hadron studies at Belle 20Particle Physics Seminar, UCL

21 PRL96, 151801 (2006), 400 fb -1 Hadronic decays K + - cont ed M, Q, t dep ent signal fractions used in decay time fit (WS): (RS decay time) largest bkg. random slow same resol. f. as signal (D 0 ) = 409.9 ± 0.7 fs x 2, y, R D free parameters toy MC: no bias B. Golob, BelleTopics in charm hadron studies at Belle 21Particle Physics Seminar, UCL

22 PRL96, 151801 (2006), 400 fb -1 Hadronic decays K + - cont ed R D = (3.64 ± 0.17 ) ·10 -3 x 2 = (0.18 ± 0.21 0.23 ) · 10 -3 y = (0.6 ± 4.0 3.9 ) · 10 -3 A D = (23 ± 47) ·10 -3 A M = (670 ± 1200) ·10 -3 Results: no CPV CPV CPV allowed: separate D 0 and D 0 tags (x 2,y,R D ) (x ±2, y ±,R D ± ) 95% C.L. (x 2, y) contour frequentist, FC ordering (0,0) lies on 96.1% C.L. contour x 2 < 0.72 ·10 -3 -0.99% < y < 0.68% no signif. CPV largest syst. due to p*(D*) selection B. Golob, BelleTopics in charm hadron studies at Belle 22Particle Physics Seminar, UCL

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

24 Outlook Mixing and CPV searches: no evidence so far semil. decays: R M < 1.2 · 10 -3 95% C.L. decays to K + - : R M < 0.4 · 10 -3 95% C.L. most stringent limits on mix ing param ers to date decays to K + n : precise WS rate meas ent PRD72, 071101 (2005), 253 fb -1 PRL96, 151801 (2006), 400 fb -1 PRL95, 231801 (2005), 280 fb -1 A. Petrov, hep-ph/0311371 B. Golob, BelleTopics in charm hadron studies at Belle 24Particle Physics Seminar, UCL

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

26 Summary B. Golob, BelleTopics in charm hadron studies at Belle 26Particle Physics Seminar, UCL 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)


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