Updates on X 3872 production at Belle. K.Trabelsi QWG6 Workshop Nara, Dec 2-5, 2008

Transcription

1 Updates on X 387 production at Belle K.Trabelsi QWG6 Workshop Nara, Dec - 5, 8

2 B- factories produce lots of c c pairs J/, ', c, c , 1, ,1 Brs~1, inclusive -- 1 only C = states...

3 B factories... since 1999 Many many B mesons... Luminosity Peak Integrated Luminosity Peak Integrated charmonium study in B decays : as example, reconstruct B K J/ Energy difference : E = Ei ECM / Beam constrained mass : Mbc = ECM / pi /cm /s 1 86 fb 1 75 fb at 4S /cm /s 531 fb fb at 4S

4 X 387 first observation PRL91,61 3 B K J/ using 14 fb 1 N=34±7 significance 1 S J / 387. ±.6 ±.5 MeV / c X 387 J / ~m D m D * [ m D m D = ±.36 MeV / c ] *.3 MeV 9 % C.L. X is narrow and doesn ' t decay to D D [PRL93, ] 4

5 X 387 confirmed by 3 other experiments PRL93,71 PRL93,16 PRD71, 7113 R 5

6 Is it a c c meson? 387 MeV States already identified 6

7 Non observation of X 387 cj decays PRL91,61 3 The radiative decays to cj expected to be large for some charmonium states... but not found c K c1 K Mbc Mbc M c1 M c B X c1 / B X J.9 at 9 % CL X expect 1.6 [potential/ '' Wigner -Eckart ] B X c / B X J 1.1 at 9 % CL X 3 expect 3.5 7

8 cc assignment? hep - ex /4733 c ' ' M too low and too small c1 too small M wrong c c should dominate 3 c && D D too small

9 First evidence for X 387 J/ hep - ex / fb 1 Look for B XK where X J/ c J/ as calibration mode 1 N=13.6±4.4 = 4 C - parity positive! X J/ =.14±.5 X J/ 9 confirmed by BaBar see B.Fulsom ' s talk

10 1 Summer 8 : update with 65 fb ArXiv : ± B ' K ± ± B X 387 K and B X 387 K S ± ± ± S B XK NS = 916±61 distributions for ' and X 387 are fitted simultaneously : detector resolution effect is automatically calibrated by ' First observation of B X 387 K S 1 B XK NS = 13± NS = 7.±

11 ± ± B X 387 K and B X 387 K ArXiv : BR B X 387 K R= =.8±.±.5 ± ± BR B X 387 K BaBar :.41±.4±.5 charged and neutral B mesons decay into X 387 with comparable BR M X = M X from B± M X from B =.18±.89±.6 MeV No mass splitting signature BaBar :.7±1.6 MeV M X = ±.37±.7 MeV m D m D = ±.36 MeV * my naive average: M X = ±. MeV CDF 8 D 4 BaBar 8 BaBar 8 11 Belle 8 CDF : M X = ±.16±.19 MeV

12 PDG '8 B charmonium K / K * BR J/ K ~ BR J/ K ~ BR J/ K * ~ BR J/ K * * * BR S K ~ BR S K ~ BR S K ~ BR S K BR c1 K ~ BR c1 K ~ BR c1 K * ~ BR c1 K * 1

13 B X 387 K, K is mostly non - resonant NR ArXiv : B 'K NS = 183±48 B X 387 K NS = 9±19 K NR is dominant! K * is dominant K is mostly K * for B charmonium J/, ', c1 K 6 BR B X 387 K NR BR X J / = 8.1± * 6 BR B X 387 K BR X J / % C.L.

14 threshold enhancement in D D PRL97, 16 6 = M = 3875.± ±.8 MeV /c BR B XK BR X D D.3 4 = 1.± BR X D D ~ 1 BR X J/ 14 * X D D /D D expected to be strongly suppressed for J=

15 ... and BaBar last summer PRD77, D* D, D = M = ±.5 MeV /c = ±.9 MeV /c 1.4 BR B XK BR X D* D =.±1.5± * 4 BR B XK BR X D D = 1.67±.36±.47 1 M X differs in D D and J/ decays? Is it the same X 387 or two different X states? 15

16 Summer 8 : new analysis with 65 fb * 1 ArXiv : D D, D NS = 48.3±11. = M = ±.4 MeV / c *.5.8 BW = MeV /c 4 BR B XK BR X D D =.73±.17±

17 Conclusion narrow and right at md m D M X = ±.37±.7 MeV * ArXiv : no mass splitting signature C = 1 well established, JPC = 1 seems likely first observation of B X 387 K, but K mostly non res. ArXiv :89.14 * was seen by Belle in D D, J/, J/, J/ recent D D * analysis: ArXiv : M X = ±.4 MeV no good charmonium candidate? so what is it? tetraquark, molecule,...? 17

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19 Possible interpretations... four - quark model L.Maiani et al, PRL99 : 183, 7 X u = [cu][c u] = X state decaying into D D = X 3876 X d = [cd][c d] = X state decaying into J/ = X 387 finding the charged partner is critical * molecule model D D bound state M X close to the D * D threshold 1, favors D D decay over J/ over J/ E.Braaten et al, PRD77: 149, 8 ( line shapes of the X depends on its decay channel, different in B or B decays )...

20 No obvious c c assignment if J PC =1 hep - ex /4733 c '' M too low and too small hc ' angular dist rules out c1 ' J / way too small c1 too small M wrong c c should dominate 3 c && DD too small

21 M looks like a concentration high M favouring X 387 J/ and hence C = 1 see also angular analysis [hep- ex /5538] ++ disfavouring PRL96, 1 6, -+ see also angular analysis [PRL98, 13 7 ] rules out hc ', J... reinforces X 387 J/ L=, PC J = 1 interpretation PC puts L=1, J = possibility back in play : c... but d c c sh be c J /

22 Evidence for X 387 J / hep ex / fb virtual 78? X J/ =1..4±.3 X J/ for M 75 MeV /c N = 1.1±4.1 Backgrounds =.1±1. significance 4.3 Large isospin violation not confirmed yet by other experiments

23 Angular analysis by Belle PC J =O ++ θ lπ hep -ex /5538 S and D waves possible but D disfavored by M and should be suppressed by phase space Decay amplitude J/. dn sin l d cos l / d.o.f =31/ 9 disfavours cos l ++

24 PC J =O J/. J/ Decay amplitude p -+ d N sin sin d cos d cos / d.o.f =18/ 9 cos disfavours / d.o.f =34/ 9 -+ cos

25 No obvious c c assignment hep - ex / 4733 c '' M too low and too small hc ' angular dist rules out c1 ' J / way too small c1 too small M wrong c c should dominate 3 c && DD too small

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