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Search for New Particles in B Decay at Belle

Search for New Particles in B Decay at Belle. Fang Fang University of Hawaii ICHEP’04, Beijing, August 2004. B K p + p - p 0 J/ y event candidates. B K w J/ y. 253 fb - 1. M(J/ y p + p - p 0 ). B K X(3872).  J/ y p + p - p 0. M( p + p - p 0 ). cut here ( >1.6 2 GeV 2 ).

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Search for New Particles in B Decay at Belle

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  1. Search for New Particles in B Decay at Belle Fang Fang University of Hawaii ICHEP’04, Beijing, August 2004

  2. BK p+p-p0J/y event candidates BKwJ/y 253 fb-1 M(J/yp+p-p0) BK X(3872) J/yp+p-p0 M(p+p-p0)

  3. cut here ( >1.62 GeV2) M2(J/yw) BK** J/y Kw M2(Kw) 1st: look at BK w J/yDalitz Plot Mbc DE Mp+p-p0

  4. Slice into 40 MeV-wide M(w J/y) bins Large deviation from phase-space Fit c2/d.o.f.=133/11

  5. Slice into 40 MeV-wide M(w J/y) bins Adding a BW helps Fit M≈3941±11 MeV G≈ 91±24 MeV

  6. M(Kw) for the signal region 3880 <M(wJ/y)<3900 MeV No peaking In M(Kw) M(Kw) (GeV)

  7. What is it? • A broad w-J/y resonance? • Above DD & DD* threshold! • More than one overlapping narrow states? • Expt’l M(wJ/y) resolution is s≈ 6 MeV • Some kind of w-J/y threshold interaction? • Does the J/y act like an ordinary hadron? • cc-gluon charmonium hybrid? • Predicted by lattice QCD but with Masses ~ 4.4 GeV

  8. Next: BK X(3872) p+p-p0J/y M(J/yp+p-p0) look along here BK X(3872) J/yp+p-p0 M(p+p-p0)

  9. events with M(3p)>0.75 GeV These events are almost pure signal Nevt=10.0 ± 3.6 S/N = 5/1 Signif = 5.8s BKX(3872); Xp+p-p0 J/y all events M(p+p-p0) Nevt=15.4 ± 6.3 S/N = 0.8/1

  10. Consistent with sub-threshold X(3872)w J/y • Mw + MJ/y = 3879 MeV (7 MeV above 3872) • Xw J/y occur via virtual w’s, 3p masses cluster at the kinematic limit. • G(XwJ/y)/G(Xp+p- J/y) = 0.8 ±0.3± 0.1 • In agreement with Swanson’s DD* bound-state model for the X(3872)[PLB 588,189 (2004)] -

  11. Other new results on the X(3872) • G(Xgc c2)/G(Xp+p-J/y) <1.1 (90%) • Below expectations for X = 3D3 (y3) • J/yqhelicity dist. inconsistent with JPC = 1+- • rules out X=21P1 (hc’) Mbc Mgcc2 c2=75/9 X |cosqJ/y|

  12. Other new results on the X(3872), cont’d • G(Xg J/y)/G(Xp+p-J/y) <0.4 (90%) • well below expectations for X = 23P1 (cc1’) Look atB g J/y K BKcc1; cc1g J/y No X(3872) M(g J/y)-M(J/y)

  13. p+p-J/ydecays violate isospin M too low and G too small angular dist’n rules out 1+- G(gJ/y) way too small G(gcc1) too small; (PRL 93, 2003) pp hc should dominate ppJ/y G( gcc2 & DD) too small No good cc candidates for X(3872) hc” hc’ cc1’ y2 hc2 y3

  14. 0-+ 1-- 1+- 0++ 1++ 2++ Y’ (2S) hc’ (2S) 3686 cc2 (1P) 3654 cc1 (1P) hc (1P) p0 3556 3525(c.o.g)?? 3510 cc0(1P) 3415 g p0 J/y (1S) hc (1S) 3097 2979 Search for the hc meson • Charmonium spectrum E760 J/yp0 3526 MeV

  15. Strategy for the hc search • M. Suzuki; Y.F. Gu et.al. suggest looking for the hc in B hc K • B(hchc g) is large ~ 50%. • hc KSK+p- is very clean • Belle has used B decays to discover the hc (2S) & X(3872) • Select KSK+p-g in hc mass region and look for B signals • Mbc • DE hchc g hc  KSK+p-

  16. 3.17 – 3.27 3.27 – 3.37 3.37 – 3.47 3.47 – 3.57 3.57 – 3.67 Are there B signals in the hc region? • Mbc distributions in five 100 MeV-wide M(KSK+p-g) bins No signal is seen

  17. hcg invariant mass distribution 3.17 – 3.67 c.o.g. Mbc sideband data Consistent with being only background

  18. c.o.g. Upper limits on B(B hcK) • Assume B(hchc g) = 0.5, we obtain upper limitson B(B hcK)at 90% C.L. Colangelo, De Fazio and Pham, hep-ph/0310084 B(B hcK)<310-4 for 3.47<M(hcg) <3.57 MeV

  19. Summary • We have observed a near-threshold wJ/y mass enhancement in B  KwJ/y. What is it? • Observation of X(3872)  wJ/y supports the DD* molecular interpretation of X. No natural charmonium assignments. • We have searched for the hc meson in the decay chain • B hc K, hchcg, hc  KSK+p. No significant • signals are seen for 3.17 < M(hcg) < 3.67 GeV.

  20. Backup Slides

  21. Look back at the p+p-p0 masses Very clear w signal 28w’s 76w’s 20w’s 26w’s

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