XYZ mesons
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Transcript of XYZ mesons
XYZ mesons XYZ News from Belle
Stephen L. Olsen, Univ of Hawai’iQWG 2006 June 26-30, Brookhaven
B-factories are Charmonium factories
cc production mechanisms @ a B factory:
• B meson decays
• e+e- annihilation
• collisions
• e+e- radiative return (isr)
cc production in B decays
j=½
j=½
J = 0 or 1
Spectator model says Jcc= 0 or 1 shoulddominate exclusive BK(cc) decays.
Allowed decays all have Bf~10-3 from PDG2004
cK 0.9 x10-3
JK 1.0 x10-3
J/K* 1.4 x10-3
’K 0.7 x10-3
’K* 0.9 x10-3
c0K 0.6 x10-3
c1K 0.7 x10-3
J/K12701.8 x10-3
BK cc(J=2) still not seen
e+e- J/ + (cc)J/
X
X (almost) alwayscontains (cc)
C(X) = +1consistent with bkg
c
c0
c’
M(X)
DD
JPC = 0++, 2++
JPC = 1--cc
e+e- (cc)
XYZ particles in Belle• X(3872)
– J/ in BKJ/
• Z(3930)– DD in DD
• Y(3940)– J/ in BK J/
• X(3940)– e+e- J/X & e+e- J/ DD*
• Y(4260)– J/ in e+e- J/ NEW
Z(3931) DD at Belle
41 11 evts (5.5)
M=3931 4 2 MeV
208 3 MeV
sin4 (J=2)
Matches well to c2’ expectationsM(DD) GeV
Belle PRL 96, 082003 (2006)
Z(3930): candidate for the c2’
3931M= 3931 MeV is
~45 MeV low
=20MeV too narrow?
Masses fromBarnes, Godfrey & Swanson
PRD 72, 054026 (2005)
e+e- J/ X(3940)
e+e-J/ + X
hep-ex 0507019 submitted to PRL
X(3940)D*D seen(DD & J/ not seen)
B(D*DD)>45%
B(DD)<41%
From X(3940) → D*D:M = (3943 ± 6 ± 6) MeV< 52 MeV at 90%CL
Is the X(3940) the c”?
3940M= 3943 MeV is ~150 MeV low
<52MeV too narrow?
X(3872) in BKJ/
M(J)
’J/
X(3872)J/
PRL 91, 262001
Also seen in pp
X(3872)
CDF
hep-ex/0406022
11.6
Production properties similar to those of the ’
X(3872)D0
PRL 93, 072004 (2004)
PRL 93, 162002 (2004)
C=+1 is establishedX(3872)J/ seen in:
&Belle
PRL 96 102002
M( looks like a
X(3872)””J/ seen
CDF Belle
Belle
hep-ex/0505037
l
|cosl|
2/dof = 34/9
|cos|
|cos|
2/dof=34/9
0++ 0-+
rule out 0++ & 0 -+
J kxJ
Ruled out by Belle
Angular analysis from CDF
Ilya Kravchenko: FPCP06
1++
or2-+
Belle: Threshold peak in BKD0D00
M=3875.4 0.7 0.8 MeV
Br(BKX)Bf(XD0D00 )
= (1.27 0.31 )x10-4
Br(XD0D00)Br(XJ/)
~ 10
+0.7-1.7
+0.22-0.39
M(D
D)
E
Belle hep-ex/0606055 today!
Comments on the D0D00 mass peak
Fitted M: 3875.4 0.7 0.8 MeV+0.7-1.7
M–(mD0+ mD*0) = +4.3 0.7 MeV+0.7-1.7
PDG05
2xPDG error on mD0
(could be 2.0 MeV)
PDG MX3872: 3871.2 0.5 MeV
Here error onmD0 drops out
Nominally ~2.3above D0D*0 threshold(but errors are non-Gaussian)
~2 discrepancy
DD* “Binding Energy?”:
X(3872) has no satisfactory cc assignment
3872
rJ/ too small& r(J/) too big
c1’
• cJ/ ispin forbidden• D0D00 @ thresh. suppressed• BKcc(J=2) suppressed
c2
Y(3940) in BK J/
M≈3940 ± 11 MeV≈ 92 ± 24 MeV
PRL94, 182002 (2005)
M(J/) MeV
(Y3940 J/ > 7 MeV (an SUF(3) violating decay)
~
this is 103 x (’ J/ (another SUF(3) violating decay)
if the Z(3930) is the c2’the Y(3940) mass is toohigh for it to be the c1’
Is there a cc slot for Y(3940) ?
Can M(c1’)>M(c2’)?c1’
Mass is lowc”
“ “ “ “c0
’
39403931
e+e- isr Y(4260) at BaBar
233 fb-1
ee+J/pb
(Y4260 J/) > 1.6MeV @ 90% CL
Y(4260)
X.H. Mo et al, hep-ex/0603024
4260
4260
BaBar PRL95, 142001 (2005)Not seen in e+e- hadrons
BES data
Y(4260) at CLEO-III
Consistent results
13.3 fb-1
ISR(1S)-(4S)
13.3 fb-1
70 +40 588 23 +6Width (MeV)
4283+17 44259 8 +2Mass (MeV)
14.1 +5.2 (4.9)125 23 (~8)N
CLEO IIIBaBar
-6-6 -16-16
-4-4
-4.2-4.2
-25-25
R.Poling @ Charm 2006
Y(4260) at Belle
MX
Select e+e- ℓ+ℓ- +X; Nchg=4
Mℓ+ℓ-=MJ/30MeV; pJ/y>2 GeV; M>0.4GeV
| data4.2<MJ/<4.4
MC
M=4295 10 +11 MeV
= 133 26 +13 MeV -6
-5
Preliminary
For ’J/ in the same data:
M(’) = 3685.3 0.1 MeV(PDG: M(’)=3686.09 0.04)
BaBar vs CLEO vs Belle
BaBar CLEO III Belle (Preliminary)
N 125 23 (~8) 14.1 +5.2 (4.9) 165 24(stat) (>7)
Mass(MeV) 4259 8 +2 4283+17 4 4295 10 +11
Width 88 23 +6 70 +40 5 133 26 +13
-6
-4
-4.2
-16
-25 -6
different
“Full” report from Belle at ICHEP in Moscow
-5
No 1-- cc slot for the Y(4260)
42804280
X.H. Mo et al, hep-ex/0603024
DD** threshold in relation to the “Y(4260)”
4.28-mD
D** spectrum
M(J/) GeV
No obviousdistortions
summary• Z(3931) (DD)
– Probably the c2’
• X(3940) (e+e- J/ X)– C=+1
– Could be the c” (albeit with some stretching)
• X(3872):– JPC = 1++
– Br(X J/) large– Br(XD0D00) seen; ~ 10xBr(XJ/y)
D*D
summary cont’d
• Y(3940)– ( Y3940 J/) >7 MeVtoo
large for charmonium– Mass too low for a hybrid
• “Y(4260)”– Confirmed by Belle but at a higher mass
– (y4260J/)>1.6 MeValso very large
– JPC=1--, but not seen in e+e- hadrons- Straddles the D**D threshold, but with no
obvious distortions to the J/ line-shape
233 fb-1
conclusions
• There is a new hadron spectroscopy in the 3.5~4.5 GeV mass region
– Maybe more than one
• The new states are characterized by large partial widths (Bfs) to hadrons+J/
– Br(X(3872)J/) > 4.3% (Isospin=1)– (Y(3940)J/) > 7 MeV (SU(3) octet)– (Y(4260)J/) > 1.6 MeV
• There is no apparent transition at the D**D mass threshold
(mine, not Belle’s)
Thank You
Back-up slides
Look at e+e-J/ D(D(*))
•Reconstruct a J/ & a D•use D0K-+ & D+K-++
•Determine recoil mass
Inclusive BKx from BaBar
?
Fully reconstructed B- tags