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Published byClarence Knight Modified over 9 years ago
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cc spectroscopy at elle S.L.Olsen Hawaii QWG 2004 Worksop IHEP Beijing _
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B-factory bonuses: new insights/puzzles about charmonium c’c’ X(3872) M(K s K ) B K K s B K + - J/ M( + - J/ cc cc c0 J/ recoil mass e + e - J/ cc ?? ‘ B K J/ M( J/ ??
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b ccs is a dominant process b c c s V cb cos C J/ , ’, c, c1,… Brs~10 -2 (inclusive) CKM favored W-W- B mesons are a good source for charmonium and other cc states
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>900pb -1 /day (~1M BBs/day) 1.2x10 34 /cm 2 /s KEKB is a good source of Bs
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Kinematic variables for the (4S) CM energy difference: Beam-constrained mass: B K c B K c B B ϒ (4S) E cm /2 ee ee KSKKSK KSKKSK M bc EE
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1 st Observation of the c ‘
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B K (K S K ± Ŧ ) M bc for 40 MeV M(K S K ) slices 3000 MeV 3640 MeV B K c B K c ’ 42fb -1 KSKKSK KSKKSK
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Fit each bin N evt = 45.3 ± 12.6 M c ’ = 3653 ± 10 MeV c ’ = 33 ± 22 MeV N evt = 90.5 ± 14.9 M c = 2978 ± 5MeV c = 33 ± 16 MeV M(K S K ) M bc EE c:c: c’:c’: 3.55 GeV 3.60 GeV 3.65 GeV 3.70 GeV 3.75 GeV … … S.K. Choi et al PRL 91, 102001
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Subsequent measurements confirm higher mass value K S K e e J/ X MxMx BaBar (preliminary) 3630 MeV 3642 MeV 3633 MeV CLEO hep-ex/0306060 elle cc cc ‘
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c ’: current status M avg =3637±4 MeV (Crystal Ball excluded)
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M(1S) = M J/ – M c =117±1 MeV M(2S) = 49 ± 4 MeV gets smaller
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The X(3872) with 253 fb -1
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B ± K ± + - J/ N ev = 48.6 ± 7.8 M = 3872.4 ± 0.7 MeV
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Now M( is really -like
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X(3872) Mass D + D* - threshold
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Look at B K J/
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M( ) M(J/ ) B K J/ X J/ B K X(3872);
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1: look at B K J/ Dalitz Plot M M bc E E M 2 (J/ ) M 2 (K ) B K* J/ KK cut here
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Slice into 40 MeV-wide M( J/ ) bins Large deviation from phase-space Fit
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Slice into 40 MeV-wide M( J/ ) bins Adding a BW helps Fit M≈3940 ± 11 MeV ≈ 92 ± 24 MeV
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M(K ) for the signal region M(K ) (GeV) 3880 <M( J/ )<3900 MeV No peaking In M(K )
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Look back at the masses 76 ’ s 28 ’ s Very clear signal 20 ’ s 26 ’ s
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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? cc-gluon hybrid? –Predicted by lattice QCD, including states with large hadron+cc widths, but predicted masses are ~ 4.4 GeV J/
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Next: B ± K ± X(3872) J/ M( ) M(J/ ) B K X(3872) J/ look along here
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M(3 J/ ) = M X(3872) ± 16.5 MeV (±3 ) Look at 25 MeV-wide M( ) mass bins EE M bc
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B-meson yields vs M( ) 12.4 ± 4.2 evts
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“Sidebands” B K J/ Non-resonant or “peaking bkgd sidebands Overlap region
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Cross-talk from B K J/ enhancement? f dm = 0.75 ±0.14 evts Check : signal yield for M(3 J/ )= M X(3872) +1 –3 (no overlap with band) 12.4 evts 11.5 evts (expect 11.0 for no X-talk)
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Other sidebands (no significant signals) 4.3 ±6.2 evts 6.4 ± 5.6 evts Area of I and III each = 4x Area o signal bin Non-res bkd in signal bin = 1.3 ± 1.0 evts
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Branching fraction Br(X J/ ) Br(X J/ ) N ev ( J/ ) ( 2 J/ ) N ev ( J/ ) ( 3 J/ ) = 0.188 0.036 13.1 ± 4.2 62.6 ± 8.3 = 1.1 ± 0.4 (stat) ± 0.3 (syst) Accept:ance: 10% Xtalk/Bkgnd: -20% X J/ : +25% M(3 )<750 MeV significance ≈ 4
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Consistent with sub-threshold X(3872) J/ M + M J/ = 3879 MeV (7 MeV above 3872) –X J/ occur via virtual ’s, 3 masses cluster at the kinematic limit. (X J/ )/ (X J/ ) = 1.1 ±0.4± 0.3 In agreement with Swanson’s DD* bound-state model for the X(3872) [PLB 588,189 (2004)] Smoking gun for qqqq interpretation of X(3872)? -
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update continuum e + e - J/ (cc) with 287 fb -1
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L=101 fb -1 2002 L=155 fb -1 2003 287 fb -1 cc c0 ‘ cc 4 th peak!! non-zero continuum below DD threshold J/ J/ negligible confirm c ’ e + e - J/ (cc) > e + e - J/ glue (e+e- J/ c ) > 10x theory evidence for c ’ 2004 -
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What is the 4 th peak? the reconstruction and selection procedure is the same as before Extend the fit region no signal of X(3872) significant (>4 ) peak at M=3940 11 MeV N=148 33 (4.5 ) the width is consistent w/ resolution (= 32 MeV) X(3872) cc cc c0 cc ‘ ‘ What is it? c0 ? c ?? ‘ “
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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 (2.1 ) c0 DD* ‘ c DD “
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What is this one? Too narrow to be the same as the J/ peak at 3940 MeV c0 or c most likely charmonium states –DD* signal rules against c0 –Mass is a little low for c M(3S) would be ≈ 100MeV can M(3S) > M(2S) ‘“ “ ‘
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Summary c ’ established M(2S)< M(1S) (X (3872) J/ = (X (3872) J/ ) –Good for molecules; bad for charmonium Broad near-threshold J/ peak –too broad for charmonium –Too light for cc-glue hybrid? –theshold interaction involving a J/ ? 4 th peak seen in e + e - J/ X –Evidence for it in DD* (rules out c0 ’ ) –If it is the c ”, M(3S) > M(2S)
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B-factory data 3 D 2 ?? h c ?? e + e - J/ “X”(3940) “Y”(3940) J/ X(3872) + - 0 J/
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M(K3 ) for signal bin Events at M(3 )=775 MeV Kinematic limit would peak here
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