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Determination of the J PC of the X(3872) (Reviews of BN800) S.L. Olsen & S.K. Choi Apr 06, 2005 Belle General Meeting
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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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P-viol’n & DD -allowed J PC s unlikely (reduce type size of these entries by x1/2) 0 - - exotic violates parity 0 -+ ” ) (Not 2 prod) 0 ++ DD allowed ( c0 ’ ) (Not 2 prod) 0 +- exotic DD allowed 1 - - DD allowed ( (3S)) Not ee X 1 -+ exotic DD allowed 1 ++ ( c1 ’ ) 1 +- (h c ’ ) 2- -(2)2- -(2) 2 - + ( 2 ) (Not 2 prod) 2 ++ DD allowed 2 ’ ) (Not 2 prod) 2 +- exotic DD allowed
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Use e7 – e37 data (include B K S J/ ) Signal (47 ev) Sidebands (114/10 = 11.4 ev)
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Product BF determination Br(B KX(3872)) x Br(X J/ ) = (1.31 ± 0.24(stat) ± 0.13(syst))x10 -5 Use PDG for ’
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Areas of investigation Search for radiative decay Angular correlations Fits to the M(pipi) distribution
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Search for X(3872) J/
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Select B K J/ (include both K ± & K s ) Tight J/ cuts K ± id>0.5 / Belle-standard “good Ks” E >40 MeV 0 veto ( 2 >4.0) K* veto (M(K )>1.0 GeV) R 2 <0.4; |cos B | < 0.8 |M bc – 5.28|<0.0055 GeV (2 ) | E|<0.034 GeV (2 ) E7 E37
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B K c1 ; c1 J/ M( J/ ) X(3872)? Use these fits to get means & sigmas for M bc and E Of X(3872) |M( J/ ) – m c1 | < 25 MeV ( ± 2.4 )
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M bc & E for 64 MeV- wide M( J/ ) bins N ev (X 3872 ) = 13.6±4.4 5.7 significance Background 2.6±0.6 Prob : 13.6 <2x10 -5
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Product BF determination Br(B KX(3872)) x Br(X J/ ) N ev (X J/ ) N BB Br(J/ l +l- ) ( X J/ ) = = (1.8 ± 0. 6(stat) ± 0.1(syst)) x 10 -6 MC:0.19±0.01
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Evidence for X(3872) J/ ( reported last summer hep-ex/0408116 also BN 761) 12.4 ± 4.2 evts B-meson yields vs M( ) >755 MeV
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C = -1 is ruled out reduce typesize of C=-1 entries 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 Changes from BAM - Use EvtGen to generate different J PC scenarios. (Thanks to help from Ishikawa-san.) - Use likelihood (<-c2 ) recommended by PDG (& Golob) for low statistics measurements
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Strategy: for each J PC, find a distrib 0 if we see any events there, we can rule it out example 1 -- : sin 2 K K compute angles in J/ restframe D.V. Bugg hep-ph/0410168v2
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’ 2 /dof = 16.3/9 ’ is 1 -- 2 /dof = 45.1/9 for X(3872) events |cos Kl | signal MC + background histogram background scaled from sidebands X(3872) is not 1 -- ! Expect 4 bin Prob : 16 evts ~5x10 -5
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1 +- and 2 -- use J/ helicity angle J/ K X J/ J/ |cos J/ | For the ’ J/ , this should be ~flat
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1 +- : sin 2 J/ 2 -- : sin 2 J/ cos 2 J/ |cos J/ | 2 /dof =31.6 /9 2 /dof =19.5 /9 rule out 1 +- 2 -- unlikely
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0 -+ Rosner (PRD 70 094023) 0 -+ : sin 2 sin 2 safe to rule out 0 -+ 2 /dof=17.7/9 |cos | |cos | 2 /dof=34.2/9
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0 ++ Rosner (PRD 70 094023) again ll In the limit where X(3872), , & J/ rest frames coincide: d /dcos l sin 2 l |cos l | rule out 0 ++ 2 /dof = 41.0/9 2 /dof = 30.1/9
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1 ++ ll 1 ++ : sin 2 l sin 2 K Rosner (PRD 70 094023)
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2 /dof = 5.0/9 2 /dof = 13.5/9 2 /dof = 11.4/9 2 /dof = 10.0/9 compute in X and J rest frame compute in X and rest frame |cos ||cos l | 1 ++ looks okay!
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Reduce type size for J PC values that fail angle tests 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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Remaining states 1 ++ & J/ in an S-wave 2 -+ “ “ a P-wave
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Fits to the M( ) Distribution X J/ in P-wave has a q* 3 centrifugal barrier X J/ q*
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M( )- dependence of the detection efficiency
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M( ) can distinguish -J/ S- & P-waves S-wave: 2 / dof = 43.1/39 P-wave: 2 / dof = 71.0/39 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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-J/ in a P-wave is unlikely reduce type-size of all J -+ entries 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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Mass is way off: 3872 vs 3929 3990 MeV we measure Rough Expectation for pure charmonium Could the X(3872) be the c1 ’ ? (2 3 P 1 J/ ) ~ 11 keV (2 3 P 1 J/ ) ~ ( ’ J/ ) ~ 0 (0.3 keV) ~ 30 isospin violating Barnes, Godfrey hep-ph/0311162 0.14+-0.05 is too small compare to 30 c1 ’ component of the X(3872) must be small theory range
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Summary 1 ++ passes all the tests consistent with observations of: X J/ & X ” ” J/ angular distributions & M( ) fitted well c1 ’ assignment unlikely (Br( J/ ) is too small) –DD* molecule models favor 1 ++ »Tornqvist hep-ph/0308277 »Swanson PLB588, 189(2004) 2++ : this is ruled out by Garima et al & Jolanta et al by observation of X DD* ( but not by this analysis)
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