1. X(3872) Review T.Aushev LPHE seminar

2. 8 February 2010T.Aushev, LPHE seminar2 Introduction Era of the new family of particles, named XYZ, started from the observation of X(3872) in the J/ψ π+π- final state by the Belle experiment Many new states have been found/observed/studied by Belle and other experiments, BaBar, CDF, D0, CLEO after that This is just a short list of them X(3872), X(3940), Y(3940), X(4160), Y(4008), Y(4260), Y(4350), Y(4660), Z(3930), Z(4415), Z(4430)+, Yb(10580), … These particles are not fittable to any of the known or predicted states Most probably it is new type of quark particles in addition to mesons and baryon, although it is not proved yet

3. Observation of X(3872) 8 February 2010T.Aushev, LPHE seminar3 X(3872) '' M(  +  - l + l - )- M(l + l - ) It did not fit to any known cc-bar states Mass of X(3872) is close to DD* What is it: charmonium, DD*-molecule, tetraquark...? Observed by Belle in B ± → K ±  +  - J/  2003 Belle data: 152 M BB events Mass = 3872.0±0.6±0.5 MeV Significance = 10 σ 152M BB, PRL91, 262001(2003)

4. Most recent measurements 0803.2838 (2008) 0809.1224 (2008) 0906.5218 (2009) 0405004 (2004) 5.2σ 12.8σ (K + ) + 5.9σ (K S ) (>> or = ∞) σ 8.6σ (K + ) + 2.3σ (K S ) 8 February 2010T.Aushev, LPHE seminar4

5. X(3872) mass measurements 8 February 2010T.Aushev, LPHE seminar5 Current mass is below the DD* threshold Recent CDF’s result is the most precise measurement of X(3872) mass Together with CLEO’s update on the D 0 mass gives hint on the X(3872) mass to be below the D 0 D *0 threshold M(X(3872)), MeV/c 2 Γ(X(3872)), MeV/c 2 B → XK 3871.46±0.37±0.0 7 <2.3 @ 90% C.L. (2003) B → XK 3871.4±0.6±0.1 <3.3 @ 90% C.L. (2008) X→J/ψπ + π – 3871.61±0.16±0.1 9 1.34 (fixed from first two) Our average3871.50±0.19 M(D 0 )+M(D *0 )3871.81±0.36

6. Determination of J PC quantum numbers of the X(3872) 8 February 20106T.Aushev, LPHE seminar

7. 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 8 February 20107T.Aushev, LPHE seminar

8. Existence of X(3872)  J/  established: C(X(3872))=+1 Belle, 275M BB, hep-ex/0505037(2005) X(3872) C-parity B ± → K ±  J/  no. of B’s in M(  J/  ) bins 13.6±4.4 ev. (4  ) M=3872 MeV  =13 MeV  J/    (2S) Relatively large fraction of  (2S)  supports D*D molecule hypothesis and possible admixture of cc-bar component BaBar, 465M BB, 0809.0042 (2009) 8 February 2010T.Aushev, LPHE seminar8

9. Isospin violation B ± → K ± (  +  -  0 )J/  Further evidence for C(X(3872))=+1 If 3  come from , 2  – from  large isospin violation, difficult to explain if X=cc state 5. 20 0  virtual →  +  -  0 8 February 2010T.Aushev, LPHE seminar9

10. J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed (y(3S)) 1 -+ exotic DD allowed 1 ++ (  c1 ’ ) 1 +- (h c ’ ) 2 - - (y 2 ) 2 - + (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 8 February 201010T.Aushev, LPHE seminar

11. X(3872) P-parity Looks like X(3872)→J/   P(X(3872))=+1 J/   : S wave P wave M(  +  - ) from B ± → K ±  +  - J/  Belle, 275M BB, hep-ex/0505038 S wave:  2 /dof=43.1/39 (CL=28%) P wave:  2 /dof=71.0/39 (CL=0.1%) For C=+1: if P=+1 L({  +  - },J/  )=0,2,… P=-1 L({  +  - },J/  )=1,3,… M(  +  - ) upper boundary is modulated by q 2L+1 centrifugal barrier: S,P waves should dominate 55% 7.7% 8 February 2010T.Aushev, LPHE seminar11

12. J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed (y(3S)) 1 -+ exotic DD allowed 1 ++ (  c1 ’ ) 1 +- (h c ’ ) 2 - - (y 2 ) 2 - + (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 8 February 201012T.Aushev, LPHE seminar

13. X(3872) properties (cont') Angular distributions in B ± → K ±  +  - J/  Belle, hep-ex/0505038 side band expected J PC =0 ++ 0 ++ (S, D waves)  ++ -- l+l+ l-l- X(J/  )  -- ++ K B 1 ++ (S, D waves) Opposite parity 0 -+ (P wave) has been also ruled out J PC =0 ++, 1 ++, 2 ++ ? |cos  | |cos  | J PC =1 ++ is disfavored is favored 8 February 2010T.Aushev, LPHE seminar13

14. J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed (y(3S)) 1 -+ exotic DD allowed 1 ++ (  c1 ’ ) 1 +- (h c ’ ) 2 - - (y 2 ) 2 - + (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 8 February 201014T.Aushev, LPHE seminar

15. CDF study of quantum numbers 8 February 2010T.Aushev, LPHE seminar15

16. J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed (y(3S)) 1 -+ exotic DD allowed 1 ++ (  c1 ’ ) 1 +- (h c ’ ) 2 - - (y 2 ) 2 - + (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 8 February 201016T.Aushev, LPHE seminar

17. J PC possibilities (for J ≤ 2) 0 -- exotic violates parity 0 -+ (  c ” ) 0 ++ DD allowed (  c0 ’ ) 0 +- exotic DD allowed 1 - - DD allowed (y(3S)) 1 -+ exotic DD allowed 1 ++ (  c1 ’ ) 1 +- (h c ’ ) 2 - - (y 2 ) 2 - + (  c2 ) 2 ++ DD allowed  c2 ’ ) 2 +- exotic DD allowed 8 February 201017T.Aushev, LPHE seminar

18. Quantum numbers summary 8 February 2010T.Aushev, LPHE seminar18 JPC = 1++ is the most favored 1++ charmonium Xc1’ state is unlikely assignment for X(3872): Potential model predicts X c1 ’ mass to be 3953-3990 MeV/c2 Large isospin violation coming from BR(X  J/ψω)/BR(X  J/ψρ) ~ 1  J/  decay of  ’ c1 should be much stronger than isospin violating decay  J/ . Experimentally the ratio is 0.14±0.05. Possible interpretation: X(3872) =D 0 D *0 molecule

19. DD * threshold enhancement in B  KDD * 8 February 2010T.Aushev, LPHE seminar19 Both saw higher mass & BR(DD*) ≈ 10x BR(π + π - J/ψ) PRD 77, 011102 (2008) D0D00D0D00 Mass, MeVWidth, MeVB + BR x 10 4 Belle3875.4±0.7 +1.2 - 2.0 1.25±0.31±0.3 0 BaBar3875.1 +0.7 - 0.5 ±0.5 3.0 +1.9 - 1.4 ±0.9 1.67±0.36±0.4 7 PRL 97, 162002 (2006) Higher X mass raised some speculations about new particle X(3875)

20. B→X(3872) K; X(3872)  D* 0 D 0 ; D* 0  D 0 (γ,π 0 ) 8 February 2010T.Aushev, LPHE seminar20 M D*D = (3872.9 +0.6 -0.4 +0.4 -0.5 ) MeV BaBar: (3875.1 +0.7 -0.5 ±0.5) MeV Γ(Belle) =(3.9 +2.8 -1.4 +0.2 -1.1 ) MeV Γ(BaBar)=(3.0 +2.5 -1.3 +0.5 -0.3 ) MeV Nsig = 50.1 +14.8 -11.1 Significance = 6.4 σ X(3872) mass shape is also well fittable by Flatte function BR(B  X(3872)(D *0 D 0 )K) = (0.73±0.17±0.13)×10 -4 NEW hep-ex:0810.0358 2 ++ is rather unlikely (at least one D wave near threshold)

21. Charged and neutral partners of X(3872) 8 February 2010T.Aushev, LPHE seminar21 12.8  B 0 →XK 0 s B + →XK + 5.9  X(3872)→J/ψπ + π – diquark-antidiquark models Xu and Xd from B 0 and B + decays  M X = 8±3 MeV Maiani et al PRD71, 014028  M X = (+0.18±0.89±0.26 ) MeV/c 2 Br(B 0 →XK 0 ) / Br(B + →XK + ) = 0.82 ± 0.22 ± 0.05 Br(B 0 →XK 0 ) Br(J/  –  + ) = (6.65 ± 1.63 ± 1.00)x10 – 6 Br(B + →XK + ) Br(J/  –  + ) = (8.10 ± 0.92 ± 0.66)x10 – 6

22. Molecule model 8 February 2010T.Aushev, LPHE seminar22 Most advanced theory which can explain all observed decay modes and their parameter is the molecule model. According to it X(3872) is the D*0D0 state with bounding energy which make its mass below D*0D0 threshold. It favors ten times larger BR to double charm in comparison with charmonium decays

23. Different models 8 February 2010T.Aushev, LPHE seminar23 X(3872) likely not a charmonium state Radial excitation of χ c1 (J PC = 1 ++ ) expected at 3950 MeV/c 2 η c2 (J PC = 2 -+ ) should have X →J/ψγ suppressed No satisfactory cc assignment D 0 D *0 molecule? Phys. Rev. D71, 074005 (2005) Would explain proximity of the D 0 D *0 threshold favors DD* decay over J/ψππ over J/ψγ (as observed) Expect X →ψ(2S)γ to be suppressed (in contradiction with observation) tetraquark state? Phys. Rev. D71, 014028 (2005) Predict 2 neutral states and 2 charged states Neutral states produced in B 0 and B + decays: Δm ≈ (7 ± 2) MeV/c 2 Measurements: Δm = (+0.18±0.89±0.26) MeV/c 2 in B →J/ψπ + π - No evidence for charged partners Mixing of D 0 D *0 and χ c1 ? Something else?...

24. Conclusion X(3872) is J PC =1 ++ state Normal cc-bar charmonium can not be assigned to this particle Most probable nature is D 0 D *0 molecule with probably admixture of normal cc-bar state 8 February 2010T.Aushev, LPHE seminar24