1. Evidence for X(3872)gJ/y S.-K. Choi S. L. Olsen Gyeongsang U
U of Hawaii
Belle ICPV meeting Jan 27, 2005

2. Select B±K± J/y g (B0KS J/y g running now)
Tight J/y cuts
Loose K± cuts
Eg>40 MeV
p0 veto (c2>4.0)
K* veto (M(Kg)>1.0 GeV
R2<0.4; |cosqB| < 0.8
|Mbc – 5.28|< GeV (2s)
|DE|<0.03 GeV (2s)
E7  E37

3. M(g J/y)
BKcc1; cc1g J/y
X signal
Region
±32 MeV
X(3872)?
M(gJ/y)

4. Expand cc1 region |M(gJ/y) – mcc1| < 25 MeV (± 2.4s)
Fit to determine
s M(gJ/y) =10.7 MeV
|M(gJ/y) – mcc1| < 25 MeV (± 2.4s)
Use these fits to get
means & sigmas
for Mbc and DE
Nev(cc1) = 510 ± 23

5. M(g J/y) in X(3872) region No peaking background M(gJ/y) sideband
±64 MeV
±32 MeV
M(gJ/y)
sideband
X(3872)
Use this fit to get
Efact for ARGUS
Nev(X3872) = 10.5 ± 4.0
Signif =  2lnL(0) -2lnL(10.5) = 4.8 s
No peaking background

6. Br(Xg J/y) determination
Br(Xp+p-J/y) =
Nev(Xg J/y)
Nev(cc1g J/y)
Nev(Xp+p- J/y)
Nev(y’ p+p- J/y)
e(cc1g J/y)
e(y’g J/y)
e(y’ p+p- J/y)
e(Xp+p- J/y)
Br(BKcc1)Br(cc1g J/y)
Br(BKy’) Br(y’p+p-J/y)  
from PDG
1.02 ± 0.22
data:
0.30 ± 0.13
~1.02± 0.10
= 0.30 ± 0.13 ± 0.06
(Previous 90% CL upper limit was <0.4)

7. ~30 Could the X(3872) be the cc1’ ?
Rough expectation for
pure charmonium:
Barnes, Godfrey hep-ph/
G(23P1  g J/y) ~ 11 keV
G(23P1  ppJ/y) ~ G(y’  po J/y) ~ 0 (0.3 keV)
~30
isospin violating
we measure 0.3; two orders-of-magnitude smaller;
 cc1’ component of the X(3872) must be small

8. Summary X(3872)gJ/y / X(3872)p+p-J/y =0.30±0.13±0.06
this says X must have C=+ (as does the XwJ/y obs.)
if 1++ (as ang. analyses prefer), can’t be too much cc1’
Next: add B0 KS g J/y & look at E39
improve signal to > 5s??

9. status
Rejected
by ang.
analyses
XgJ/y
forbidden