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Non-standard mesons Stephen L. Olsen University of Hawai’i Representing Belle Fermilab seminar May 10, 2005
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test of QCD: “running” s
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Probe QCD from other directions non-qq or non-qqq hadron spectroscopies: Pentaquarks: e.g. an S=+1 baryon Glueballs: gluon-gluon color singlet states Multi-quark mesons: qq-gluon hybrid mesons uc u c cc u d u s d
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Pentaquarks? “Seen” in many experiments BaBar High interest: 1 st pentaquark paper has ~500 citations Belle BES but not seen in just as many others CDF Compass Jlab p
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Pentaquark Scoreboard Positive signals Negative results Also: Belle Compass L3 Jlab(CLAS) ( p K + K s n) Yes: 17 No: 18
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Existence of Pentaquarks is not yet established
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Narrow multi-quark mesons? D sJ (2317) & D sJ (2457) X(3872) J/ CLEO M(D s ) M(D s * ) M( J ) BaBar Belle
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What are the D sJ states? Belle found B D D sJ (2317) D D sJ (2457) and D sJ (2457) D s
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Angular analysis for B D D sJ D sJ D s ( ) J=1 J=0 D sJ (2317) D s 0 J=1 J=2 D sJ (2460) D s z J z =0 D sJ (2317) = 0 + D sJ (2547) = 1 + J=0
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D sJ fit into cs spectrum (with a mass shift) D sJ (2547) = 1 + D sJ (2317) = 0 +
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D sJ states are likely ordinary L=1 cs mesons (with perhaps some tetraquark mixture) Potential models got the masses wrong Chiral models seem to work OK See, e.g. Bardeen, Eichten & Hill PRD68, 054024
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non-standard mesons with “hidden charm” standard cc mesons are: –best understood theoretically –narrow & non overlapping c + c systems are commonly produced in B meson decays. b c c s V cb cos C CKM favored W-W- cc uc u c (i.e containing c & c)
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Thanks to KEKB, Belle has lots of B mesons (>1M BB pairs/day) >1fb -1 /day Design: 10 34
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Is the X(3872) non-standard? B K J/ M( J ) –M(J/ ) ’ J/ X(3872) J/
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Its existence is well established seen in 4 experiments X(3872) CDF X(3872) D0 hep-ex/0406022 9.4 11.6 PRL 93, 072001 PRL 93, 162002 PRD 71, 071103(R)
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Is it a cc meson? These states are already identified 3872 MeV Could it be one of these?
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no obvious cc assignment 3872 c ” h c ’ c1 ’ 2 c2 3 M too low and too small angular dist’n rules out 1 J/ way too small c too small;M( ) wrong c & DD) too small c should dominate SLO hep-ex/0407033
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go back to square 1 Determine J PC quantum numbers of the X(3872) with minimal assumptions
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J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2- -(2)2- -(2) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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J PC possibilities 0 -- ruled out; J P =0 +,1 - & 2 + unlikely 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2- -(2)2- -(2) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Areas of investigation Search for radiative decays Angular correlations in X J/ decays Fits to the M( ) distribution Search for X(3872) D 0 D 0 0
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Search for X(3872) J/
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Kinematic variables CM energy difference: Beam-constrained mass: B K J B K J B B ϒ (4S) E cm /2 ee ee M bc EE
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Select B K J/ B K c1 ; c1 J/ X(3872)? 13.6 ± 4.4 X(3872) J/ evts (>4 significance) M( J/ ) Bf(X J/ ) Bf(X J/ ) =0.14 ± 0.05 M bc
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Evidence for X(3872) J/ reported last summer hep-ex/0408116) B-meson yields vs M( ) Br(X 3 J/ ) Br(X 2 J/ ) = 1.0 ± 0.5 Large (near max) Isospin violation!! A virtual (782)? 12.4 ± 4.2 evts M( ) MeV
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C=+1 is established X J/ only allowed for C=+1 same for X ” ”J/ (reported earlier) M( ) for X J/ looks like a CDF
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J PC possibilities (C=-1 ruled out) 0 -- exotic Violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Angular Correlations K J/ J=0 X 3872 J z =0 z Rosner (PRD 70 094023) Bugg (PRD 71 016006) Suzuki, Pakvasa (PLB 579 67)
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Use 253 fb -1 ~275M BB prs exploit the excellent S/N Signal (47 ev) Sidebands (114/10 = 11.4 ev) X J/ ’ J/
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Example: 1 -- dN/dcos sin 2 K K compute angles in J/ restframe D.V. Bugg hep-ph/0410168v2 ’ 2 /dof = 8.9/9 Use B K ’ ’ is 1 -- K J/ ’’ z
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|cos Kl | for X(3872) events X(3872) is not 1 -- ! expect 2~3evts/bin background scaled from sidebands fit with sin 2 Kl + bkgd 2 /dof = 60.3/9 see 8 evts/bin
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0 ++ ll In the limit where X(3872), , & J/ rest frames coincide: d /dcos l sin 2 l rule out 0 ++ |cos l | 2 /dof = 34/9 M J/ ·
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0 -+ 0 -+ : sin 2 sin 2 safe to rule out 0 -+ |cos | |cos | 2 /dof=34/9 2 /dof=18/9 M p J/ · ( J/ x
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1 ++ ll dN/dcos dcos sin 2 l sin 2 K 1 ++ looks okay! |cos l | 2 /dof = 11/9 |cos | 2 /dof = 5/9 compute angles in X(3872) restframe M | X x J/ x
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J PC possibilities (0 -+ & 0 ++ ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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Fits to the M( ) Distribution X J/ has a q* (2l+1) centrifugal barrier X J/ q*
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M( ) can distinguish -J/ S- & P-waves S-wave: 2 / dof = 43/39 P-wave: 2 / dof = 71/39 q* roll-off q* 3 roll-off (CL=0.1%) (CL= 28%) Shape of M( ) distribution near the kinematic limit favors S-wave
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Possible J PC values (J -+ ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed
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X(3872) D 0 D 0 0 ?
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Select B K D 0 D 0 0 events | E| 11.3±3.6 sig.evts (5.6 ) Bf(B KX)Bf(X DD )=2.2 ± 0.7 ± 0.4x10 -4 Preliminary D *0 D 0 0 ? M(D 0 D 0 0 )
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X(3872) DD rules out 2 ++ 1 ++ : DD* in an S-wave q* 2 ++ : DD in a D-wave q* 5 Strong threshold suppression
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Eliminate all other factors and the one which remains must be the truth Sherlock Holmes The Sign of Four
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Possible J PC values (2 ++ ruled out) 0 -- exotic violates parity 0 -+ ( c ” ) 0 ++ DD allowed ( c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2 - - ( 2 ) 2 - + ( c2 ) 2 ++ DD allowed c2 ’ ) 2 +- exotic DD allowed 1 ++
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can it be a 1 ++ cc state? 1 ++ c1 ’ –Mass is ~100 MeV off – c1 ’ J/ not allowed by isospin. Expect: Bf( c1 ’ J/ )<0.1% BaBar measurement: Bf(X J/ )>4% 3872 - ( c1 ’ J/ ) / ( c1 ’ J/ ) Expect: ~ 40 ( X 3872 J/ ) / ( X 3872 J/ ) Measure: 0.14 ± 0.05 c1 ’ component of X(3872) is ≤ few%
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c2, c0 << c1 X(3872) production much lower than for other Charmonium states: can set lower limit on B.F. Can measure absolute B.F.’s of B - K - X 0 e + e - B + B - K - X 0 Lower limit on BF(X J/ ) > 4.3% @ 90% C.L 244 fb -1 Very clear J/ and c signals N J/ =258+- 42 N c =266 +-42 c2 c1 c0 J/ Jon Coleman Moriond-QCD March 2005 From BaBar: D(*)+D(*)+ fully reconstructed
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Intriguing fact M X3872 =3872 ± 0.6 ± 0.5 MeV m D0 + m D0* = 3871.2 ± 1.0 MeV lowest mass charmed meson lowest mass spin=1 charmed meson X(3872) is very near DD* threshold. is it somehow related to that?
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D 0 D* 0 bound state (deuson)? pn DD* deuteron: 2 loosely bound qqq color singlets with M d = m p +m n - deuson: 2 loosely bound qq color singlets with M = m D + m D* - attractive nuclear force attractive force?? Tornqvist hep-ph/0308277 u c u c Voloshin & Okun JETP Lett 23, 333 (1976) Bander et al PRL 36, 695(1976) DeRujula et al PRL 38, 317 (1977) Manohar & Wise, NP B339, 17 (1993) Tornqvist, Z Phys C61, 525(1994)
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X(3872) = D 0 D* 0 bound state? J PC = 1 ++ is favored M ≈ m D0 + m D0* Maximal isospin violation is natural ( & was predicted) : |I=1; I z = 0> = 1/ 2 (|D + D* - >+ |D 0 D* 0 >) |I=0; I z = 0> = 1/ 2 (|D + D* - > - |D 0 D* 0 >) |D 0 D* 0 > = 1/ 2 (|10> - |00>) (X J/ ) < (X J/ ) was predicted Equal mixture of I=1 & I =0 Swanson PLB 598, 197 (2004) Tornqvist PLB 590, 209 (2004) Swanson PLB 588, 189 (2004)
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X(3872) conclusion J PC = 1 ++ cc content is small matches all(?) expectations for a D 0 D* 0 bound state CC u c u c a non-qq meson
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Are there others? Is the X(3872) a one-of-a-kind curiousity? or the 1 st entry in a new spectroscopy? Look at other B decays hadrons+J/ B K J/ B K J/ B K J/
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B K J/ in Belle “Y(3940)” M≈3940 ± 11 MeV ≈ 92 ± 24 MeV M bc S.K. Choi et al hep-ex/0408126 to appear in PRL Bf(B KY)Bf(Y J/ )=7.1 ± 1.3 ± 3.1x10 -5
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Y(3940): What is it? Charmonium? –Conventional wisdom: J/ should not be a discovery mode for a cc state with mass above DD & DD* threshold! Some kind of -J/ threshold interaction? –the J/ is not surrounded by brown muck; can it act like an ordinary hadron? J/ Brambilla et al (QWG) hep-ph/0412158 Eichten, Lane & Quigg PRD 64, 094019 Barnes, Godfrey & Swanson hep-ph/0505002
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Y(3940): What is it (cont’d) ? another tetraquark? –M ≈ 2m Ds –not seen in Y J/ ( contains ss) –width too large?? –no exchange for D S D S s c s c ?? PRL 93, 041801 M( J/ )
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Y(3940): What is it (cont’d) ? cc-gluon hybrid? –predicted by QCD, –decays to DD and DD* are suppressed (“open-charm” thresh = m D + m D** = 4.3 GeV) –large hadron+J/ widths are predicted –masses expected to be 4.3 ~ 4.4 GeV (higher than what we see) cc Horn & Mandula PRD 17 898 (1978) Close PLB 342, 369 McNiele et al PRD 65 094505 Isgur et al PRL 54, 869 (1995)
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Another one? What is it? c0 ? c ?? ’” cc cc c0 ‘ e + e - J/ + X >4 )peak at M=3940 11 MeV N=148 33 evts Width consistent w/ resolution (= 32 MeV) (e+e-) J/ c = 25.6 ±2.8 ± 3.4 fb) (e+e- J/ (cc))/ (e+e- J/ X) = 0.82 ± 0.15 ± 0.14
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Look at e + e - J/ D(D ( * ) ) Reconstruct a J/ & a D use D 0 K - + & D + K - + + Determine recoil mass
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Look at M(DD ( * ) ) DD* DD 3940 MeV 9.9 ± 3.3 evts (4.5 ) 4.1 ± 2.2 evts (~2 ) c0 DD* ‘
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Could this be the c ”? strange M n ( )-M n ( c ) splitting pattern M = 118 ± 3 MeV M = 48 ± 5 MeV M ~ 100 MeV?? (1S) (2S) (3S) 4040 3686 3096 cc cc cc ‘ “ decreases then increases?
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Could this be the c ”? (1S) (2S) (3S) 4040 3686 3096 cc cc cc ‘ “ D ( * ) D ( * ) coupling pushes (3S) up, increases the splitting 2 3 S-1 3 D 1 mixing + DD coupling pushes (2S) down splitting smaller DD DD* D*D* Probably OK
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Summary X(3872): –J PC established as 1 ++ –cc component is small (≤ few %) –all properties consistent with a D 0 D* 0 bound state uc u c a non-standard meson cc ????? needs more study Y(3940): –No obvious cc assignment –tetraquark seems unlikely –cc-gluon hybrid? X(3940): –Probably the c ”
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Mahalo
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Announcement
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Back-up slides
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M( J/ ) look-back plot
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Fit cos l with 1 ++ MC |cos l | 2 /dof=11.9/9
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