New Resonances at Belle Jolanta Brodzicka INP Krakw
New Resonances at Belle Jolanta Brodzicka INP Kraków For the Belle Collaboration XLIV Cracow School of Theoretical Physics, Zakopane May 28 - June 6, 2004 Topics : • heavy-light mesons • cs : DSJ in e+ e- cc continuum and B exclusive decays • cu : D** in B D(*) + - decays • charmonium-like state X(3872)
The Belle Collaboration A World-Wide Activity: ~300 People from ~50 Institiutions Jolanta Brodzicka, INP Kraków , Belle Coll.
KEK-B Factory KEKB : Asymmetric e+e- collider • Two separate rings e+ (LER) : 3. 5 Ge. V e- (HER) : 8. 0 Ge. V • CM energy : 10. 580 Ge. V at (4 S) e+e- (4 S) BB • Parameters • 3016 m circumference • ± 11 mrad crossing angle • History: Physics run since June 1999 • Luminosity peak: 1. 3 x 1034 cm-2 s-1 (achieved: 20 May 2004) • Integrated Luminosity: 250 fb-1 ~ 260 x 10 6 BB ~ 300 x 10 6 cc continuum events Jolanta Brodzicka, INP Kraków , Belle Coll.
Belle Detector Event reconstruction Aerogel Cherenkov Counter Time of Flight Counter Charged track Central Drift Chamber (CDC) Silicon Vertex Detector (SVD) Electron and photon Electromagnetic Calorimeter (ECL) Particle identification K/ separation CDC : d. E/dx Aerogel Cherenkov Counter (ACC) Time of Flight Counter (TOF) electron identification SC Solenoid 1. 5 T ECL KL and identification KL and muon detector (KLM) Vertexing SVD Silicon Vertex Detector KL / Detector Electromagnetic Calorimeter Jolanta Brodzicka, INP Kraków , Belle Coll.
New observations at B-Factories • Ba. Bar with 91 fb-1 on/off (4 S) discovered resonance DSJ(2317) DS± 0 • isospin violating decay , narrow state ( < 10 Me. V ) • Ba. Bar also saw peak in DS 0 mass distribution @ ~2460 Me. V Interpreted as cross-feed from 2317 (DS from 2317 + random ) • CLEO (13. 5 fb-1) confirmed DSJ(2317) established DSJ(2463) DS *± 0 • Belle (87 fb-1) saw both : DSJ(2317) DSJ(2457) states in cc continuum & in B decays Interpretations: Ø DSJ(2317) DSJ(2457) identified with : 0+ , 1+ orbitally excited P-wave cs states Inconsistent with model predictions. Expected: broad states with masses: 2. 48 2. 53 Ge. V (above D(*)K threshold) Ø more exotic assignments : DK molecule, multiquark state, mixing P-wave cs states with 4 -quark csqq states ( masses shifted below D(*)K ) Jolanta Brodzicka, INP Kraków , Belle Coll. Topic of this talk
Potential Model for Q q Godfrey-Isgur (1985) Basic hypotheses of constituent quark model : • mesons : valence-quark configuration • dynamics described by a Hamiltonian: • relativized • confinement with running s • one gluon exchange dominates at short distance Inter-quark potential : VQq Hconf + Hspin-spin (color-hyperfine) + Hspin-orbit (1 -gluon-exch) + Hspin-orbit (Thomas precession) Heavy Quark Symmetry: m. Q Q at rest (no chromomagnetic field, static source of chromoelectric field) , Q decouples from q (~hydrogen atom) dynamics of the q meson properties Angular momentum of the light quark Q Total spin of a meson q separately conserved Jolanta Brodzicka, INP Kraków , Belle Coll.
Predictions for cu and cs mesons based on Heavy Quark Symmetry • L=1 Parity+ • jq= ³/2 J =2 J=1 • j q= ½ J = 1 J=0 • L = 0 Parity • jq = ½ J= 1 J= 0 spin-orbit D*2 (2462) D 1 (2421) D’ 1 2. 44 Ge. V D*0 2. 40 Ge. V DSJ(2573) DS 1(2536) D’S 1 2. 53 Ge. V DS 0 2. 48 Ge. V D* (2007) D (1865) Ds* (2112) Ds (1968) spin-spin hyperfine splitting , Belle Coll. till last summer relativistic correction to HQ S : an expansion in powers of • P-wave states with jq= ½ : expected to be broad (S-wave decays) difficult to identify experimentally (jq= ³/2 states: narrow) • Also some predictions that: m( jq= ½ ) > m(jq= ³/2 ) Jolanta Brodzicka, INP Kraków Missing doublets 1 /m Q
DSJ(2317) @ Belle • data sample: 87 fb-1 Events/5 Me. V • e+e- cc Ds± 0 X (inclusively-produced) • Ds ± ( K- K+ ) ± p* (Ds ± 0 ) > 3. 5 Ge. V (p in CMS) (to reduce combinatorial background) DK threshold Fitted signal: 761 44 (stat) 30 (syst) 0 /DS ± sidebands M( DS 0 ) - M( DS ) Ge. V/c 2 M(DSJ(2317)) = 2317. 2 ± 0. 5 (stat) ± 0. 9 (syst) Me. V/c 2 < 4. 6 Me. V/c 2 (90% C. L. ) Jolanta Brodzicka, INP Kraków , Belle Coll. Small peak : feed-down from DSJ(2457)
DSJ(2457) @ Belle • e+e- cc Ds* 0 X ( Ds*± 0 inclusively produced ) • Ds*± Ds ± ( K- K+ ) + p* (Ds*± 0 ) > 3. 5 Ge. V ± Events/5 Me. V Fitted signal: 126 25 (stat) 12 (syst) DS * ± sideband M( D*S 0 ) - M( D*S ) Ge. V/c 2 M(DSJ(2457)) = 2456. 5 ± 1. 3(stat) ± 1. 3(syst) Me. V/c 2 < 5. 5 Me. V/c 2 (90% C. L. ) „Peaking” background sources: • Signal feeddown from DSJ(2317)+ random soft • „Broken” DSJ(2457) signal : Ds* with „bad” Test of nature of DSJ : search for other decay modes Jolanta Brodzicka, INP Kraków Sideband-subtracted distribution , Belle Coll.
Decay modes of DSJ Events/5 Me. V DSJ(2317) region DSJ(2457) DS± + - 152 18 M( DS ) - M( DS ) Ge. V/c 2 BR( DSJ(2457) DS± ) BR( DSJ(2457) Ds*± 0 ) = 0. 55 ± 0. 13(stat) ± 0. 08(syst) (D’S 1 assumption: 0. 62 ) Events/3 Me. V DSJ(2457) DS± 59 11 DS 1 (2536) M( DS + - ) - M( DS ) Ge. V/c 2 BR( DSJ(2457) DS± + - ) BR( DSJ(2457) Ds*± 0 ) = 0. 14 ± 0. 04(stat) ± 0. 02(syst) Dipion mode st 1 time observed (D’S 1 assumption: 0. 16 ) Godfrey, Phys. Lett. B 568, 254 (2003) DSJ(2457) : JP 0+ , 0 - favours JP= 1+ DSJ(2317) : favours JP= 0+ • No signal observed in: ± ± DSJ(2457) Ds* , Ds 0 ± ± ± DSJ(2317) Ds , Ds* , DS + Jolanta Brodzicka, INP Kraków , Belle Coll. From conservation of angular mom. and parity
DSJ in cc continuum - summary • Belle observed DSJ(2317) DS± 0 and DSJ(2457) DS *± 0 inclusively produced in e+e- cc continuum • radiative and dipion decay modes of DSJ(2457) observed • the spin-parities 0+ (DSJ(2317)) and 1+ (DSJ(2457)) are favoured Jolanta Brodzicka, INP Kraków , Belle Coll.
DSJ in B exclusive decays Motivations: • Assignments of DSJ(2317) and DSJ(2457) being orbitally excited cs mesons need confirmation • If DSJ(2317) and DSJ(2457) are cs states : can be observed in B D Ds. J decays expected BF ~ 10 -2 10 -3 , quite large Tree type diagram processes • States cs with j q= ½ “easier” produced in B decays than those with j q= ³/2 (HQET) • States produced in B decay can be polarized: from angular distributions J P • In B decays : background reduction Jolanta Brodzicka, INP Kraków , Belle Coll.
Method of full B reconstruction e+e- (4 S) BB m (m. B+m. B) • Experimental conditions: • For B decay to specific final state: B f 1 f 2…f n In (4 S) frame Energy-Momentum conservation: Kinematical constraints are used Kinematical Variables: • Energy difference • Beam-constrained mass resolution improvement, background separation Jolanta Brodzicka, INP Kraków , Belle Coll.
Reconstructed modes: Both isospin related modes B D Ds. J decays B+ D 0 Ds. J+ B 0 D- Ds. J+ Signal extracted in E, Mbc and M(DSJ) Plot one of them with cuts on the others Events/10 Me. V data sample: 115 fb-1 E Ge. V DS± decay angle of in DSJ (2457) DS± (B D DSJ ) M( DSJ ) Ge. V/c 2 J=2 hypothesis J=1 hypothesis Jolanta Brodzicka, INP Kraków , Belle Coll.
DSJ in exclusive B decays – summary BR(B DDSJ) BR(DSJ) comparison: BR(DDSJ)x. BR( DSJ(2457) DS± ) BR(DDSJ)x. BR( DSJ(2457) Ds* ± • first observation of DSJ states in B decay in Belle • no new DSJ decay modes in comparison to inclusive production • masses and widths consistent • DSJ (2457) angular analysis consistent with J=1 • measured BR’s do not exclude cs states assignments Jolanta Brodzicka, INP Kraków , Belle Coll. 0 ) 0. 4
New D**0 states expected decay modes: D- + , D*- + • data sample : 60 fb-1 • Dalitz analysis for : B + D- + + (~1100 signal events) and B+ D*- + + (~600 events) both with good S/B • unbinned likelihood fit performed with signal density function: S (M 12, M 22 ) = Ai exp(i i ) BWi (M 1 2, M 2 2 ) + Aexp(i ) 2 R(M 2) coherent sum of the amplitudes of D** states which can contribute and phase space term convolution with experimental resolution Jolanta Brodzicka, INP Kraków , Belle Coll.
D**0 mesons Dalitz plot projections with fit results Background M ( D min ) Ge. V/c 2 Background M ( D* min ) Ge. V/c 2 First observation of D*0 and D 1’ 0 Jolanta Brodzicka, INP Kraków , Belle Coll.
D**0 - summary • Belle observed for the first time broad D*0 and D 1’ 0 states in B decays (observed also by FOCUS, poor agreement in measured masses) • Identified as 0+ and 1+ orbitally excited cu doublet (with j q= ½ ) • Narrow 1+ , 2+ states: D 10 and D 2* 0 also seen (already observed by CLEO) • Masses and widths of four D** states were measured Jolanta Brodzicka, INP Kraków , Belle Coll.
Measured masses versus model predictions • In cu spectrum: masses of D, D** consistent with model expectations • In cs case: masses of new DSJ (2317) and DSJ (2457) inconsistent Model expectation: M(cs ) – M(cu) 100 Me. V Chiral symmetry broken chiral partners split off (states with opposite parity) DSJ (2317) and DSJ (2457) interpreted as chiral partners of DS and D*S ? Nowak’s talk Jolanta Brodzicka, INP Kraków , Belle Coll.
Discovery of X(3872) • Belle data sample: 140 fb-1 • in B decay B ± K± + - J/ J/ l+ l- For B signal extracted in E, Mbc M( + - l+ l- ) - M( l+ l- ) Ge. V M( + - l+ l - ) - M( l+ l - ) New state is not reflection from any known state new narrow charmonium-like state : X(3872) J/ + Jolanta Brodzicka, INP Kraków , Belle Coll.
X(3872) S = 35. 7 6. 8 (10 ) Events/5 Me. V Events/15 Me. V Events/5 Me. V • Signal B ± X(3872)K± extracted in E, Mbc and M( J/ + - ) • Plot one of them with cut on the others • Simultaneous fit in 3 variables E Ge. V Mbc Ge. V MX = 3872. 0 ± 0. 6(stat) ± 0. 5(syst) Me. V M ( J/ + - ) Ge. V X < 2. 3 Me. V (90% C. L. ) • MX > M(D + D ) open-charm decay possible, why so narrow ? • X produced in B decays: J cannot be high • Is it charmonium state? • One of the unobserved higher charmonium states 13 DJ 11 D 2 23 P 1 21 P 1 ? (predicted masses @ X mass region) • MX M(D 0 + D*0 ) loosely bounded molecular or hybrid state? Jolanta Brodzicka, INP Kraków , Belle Coll.
Properties of X(3872) • Checking hypothesis that X(3872) is charmonium state radiative X decays should be observed c 2 3 D c 3 ? X(3872) c 1 , c 2 • B K c 1 ± Events/4 Me. V ± Theory: (3 D c 2 J/ c 1(1 P) J/ No signal in X(3872) region Events/10 Me. V Events/5 Me. V Jolanta Brodzicka, INP Kraków ) ( X(3872) J/ + - ) 0. 89 (90% C. L. ) c 2(1 P) J/ Mbc Ge. V + - 2. ( X(3872) c 1 ) M ( c 1 ) Ge. V Mbc Ge. V • B ± K± c 2 (3 Dc 2 c 1 ) Events/8 Me. V 3 D (Eichten, Lane, Quigg) ( X(3872) c 2) ( X(3872) J/ + - ) 1. 1 (90% C. L. ) M ( c 2 ) Ge. V , Belle Coll. 3 D c 2 & 3 D c 3 ruled out
Properties of X(3872) 23 P 1 ? X(3872) J/ B K J/ ± ± Theory: ( 23 P 1 J/ ) ( 23 P 1 J/ + - ) 11 ke. V / 0. 3 ke. V 30 Absence of X(3872) ’c 1 ( 23 P 1 ) ruled out M ( J/ ) - M ( J/ ) Ge. V h’c ( 21 P 1 ) ? Prediction for 1+ : 1 - cos 2 (J/ ) J/ decay angle in X(3872) J/ + - (B K X(3872) ) cos (J/ ) Jolanta Brodzicka, INP Kraków , Belle Coll. h’c 1 ( 21 P 1 ) ruled out
X(3872) – summary • New unexpected state X(3872) observed by Belle MX = 3872. 0 ± 0. 6(stat) ± 0. 5(syst) Me. V X < 2. 3 Me. V (90% C. L. ) (also seen at Fermilab in pp collisions and Ba. Bar ) • Still no obvious charmonium assignment • Is it D 0 D*0 molecule? Jolanta Brodzicka, INP Kraków , Belle Coll.
Summary • Many charm results from Belle. Some of them unexpected or/and inconsistent with theoretical expectations. • B-Factory is a Charm Factory, too. In adition B decays are good and clear ground to study charm spectroscopy. Jolanta Brodzicka, INP Kraków , Belle Coll.
Jolanta Brodzicka, INP Kraków , Belle Coll.
D mesons L=1 Jolanta Brodzicka, INP Kraków , Belle Coll. Ds mesons L=1
Jolanta Brodzicka, INP Kraków , Belle Coll.
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