Transcript The mystery of the X(3872)

Nonstandard mesons
Stephen L. Olsen University of Hawai’i
•tetra-quarks
u c
c u
•meson-meson molecules
•q q – q q diquark pairs
•q q-gluon hybrids
c
u c
c u
c
•nucleon-antinucleon baryonium
u d
u
u
d u
This talk
• Candidate non-standard mesons with
hidden charm from Belle & BaBar
c
u c
c u
probably no time for:
• Candidate baryonium
meson from BES
u d
u
u
d u
c
Concentrate on “hidden charm” systems
(i.e containing c & c)
u c
c u
c
c
• standard cc mesons are:
– best understood theoretically
– narrow & non overlapping
• c c systems are prolifically produced in B
meson decays.
b
Vcb
W- cosqC
CKM favored
s
Thanks to KEKB, Belle has lots of B mesons
(>1M BB pairs/day)
>1fb -1/day
Design: 10 34
Charmonium primer
These states
have not yet
been found
DD(*) decays dominate
G~wide (10’s of MeV)
Hadronic transitions
G(y’p+p-J/y) 70 keV
G(y”p+p-J/y) 50 keV
G(y’hJ/y)  5 keV
SUF(3) violating
p+p-
These states
have all been
identified
Below DD(*) thresholds
G~narrow (~<MeV )
G(y’p0J/y)  0.3 keV
isospin violating
EM transitions
G(E1)  100~300 keV
G(allowed M1)  1 keV
X(3872)p+p-J/y
BK p+p-J/y
y’p+p-J/y
X(3872)p+p-J/y
S.-K.Choi, S.L.Olsen et al (Belle)
PRL 91 262001 (2003)
M(ppJ/y) –M(J/y)
The X(3872) is well established
seen in 4 experiments
CDF
9.4s
11.6s
X(3872)
BaBar
D0
X(3872)
Is it a cc meson?
If so, it must be
one of these?
3872 MeV
no obvious cc assignment
3872
hc”
M too low and G too small
hc’
angular dist’n rules out 1+-
cc1’
G(gJ/y) way too small
y2
G(gcc1) too small;M(p+p-) wrong
hc2
y3
pp hc should dominate
G( gcc2 & DD) too small
SLO hep-ex/0407033
go back to square 1
Determine
PC
J
quantum numbers
of the X(3872)
with minimal assumptions
PC
J
possibilities
(for J ≤ 2)
-0
-+
0
++
0
+0
exotic
violates parity
(hc”)
DD allowed
exotic
DD allowed
1
-+
1
++
1
+1
DD allowed
(cc1’)
(y(3S))
exotic
DD allowed
(hc’)
2
+
2
++
2
+2
(y2)
(hc2)
DD allowed
exotic
DD allowed
(cc0’)
(cc2’)
JPC possibilities
0-- ruled out; JP=0+,1- & 2+ unlikely
0--
-+
0
++
0
+0
(hc”)
DD allowed
exotic
DD allowed
1
-+
1
++
1
+1
DD allowed
(cc1’)
(y(3S))
exotic
DD allowed
(hc’)
2
+
2
++
2
+2
(y2)
(hc2)
DD allowed
exotic
DD allowed
exotic
violates parity
(cc0’)
(cc2’)
Strong evidence for C=+1
X(3872)gJ/y
X(3872)p+p-p0J/y
virtual w(782)?
M(p+p-p0)
13.6 ± 4.4 X(3872)gJ/y
evts (>4s significance)
Bf(XgJ/y)
Bf(XppJ/y)
Br(X3pJ/y)
Br(X2pJ/y) = 1.0 ± 0.5
X(3872)p+p-J/y
=0.14 ± 0.05
Fits to r(760)
M(p+p-)
JPC possibilities
(C=-1 ruled out)
0-exotic
Violates
parity
1- DD allowed
(y(3S))
2- -
(y2)
-+
0
++
0
(hc”)
DD allowed
0+exotic
DD allowed
(cc0’)
-+
1
++
1
exotic
DD allowed
(cc1’)
+
2
++
2
(hc2)
DD allowed
(cc2’)
1+(hc’)
2+exotic
DD allowed
Angular
Correlations
r
Jz=0
X3872
J=0
z
K
Rosner (PRD 70 094023)
Bugg (PRD 71 016006)
Suzuki, Pakvasa (PLB 579 67)
J=0
J/y
0++
ereJ/y
0-+
k(erxeJ/y)
q
qlp
y
c2/dof=18/9
c2/dof = 34/9
c2/dof=34/9
|cosq|
|cosqlp|
rule out 0++ & 0 -+
|cosy|
JPC possibilities
(0-+ & 0++ ruled out)
0-exotic
violates parity
1- -
DD allowed
(y(3S))
2- (y2)
0-+
0++
0+-
(hc”)
DD allowed
(cc0’)
exotic
DD allowed
-+
1
++
1
1+-
exotic
DD allowed
(cc1’)
+
2
++
2
(hc2)
DD allowed
(cc2’)
(hc’)
2+exotic
DD allowed
M(pp) can distinguish
r-J/y S- & P-waves
S-wave:
c2/dof
= 43/39
(CL= 28%)
P-wave: c2/dof = 71/39
(CL=0.1%)
q*
roll-off
Shape of M(pp) distribution near
the kinematic limit favors S-wave
q*3
roll-off
Possible JPC values
(J-+ ruled out)
0-exotic
violates parity
0-+
(hc”)
1- -
1-+
DD allowed
(y(3S))
exotic
DD allowed
2- (y2)
2- +
(hc2)
0++
DD allowed
(cc0’)
++
1
0+exotic
DD allowed
1+(hc’)
(cc1’)
++
2
DD allowed
(cc2’)
2+exotic
DD allowed
0
0
0
X(3872) D D p
?
D*0D0p0?
• 1++ : DD* in an S-wave  q*
• 2++ : DDp in a D-wave  q*5
Strong threshold suppression
M(D0D0p0)
11.3±3.6 sig.evts (>4s)
Bf(BKX)Bf(XDDp)=2.2±0.7±0.4x10-4
Possible JPC values
(2++ ruled out)
0--
0-+
0++
0+-
exotic
violates parity
(hc”)
DD allowed
exotic
DD allowed
1- -
1-+
DD allowed
(y(3S))
exotic
DD allowed
++
1
(hc’)
2- (y2)
2- +
(hc2)
2++
2+-
DD allowed
exotic
DD allowed
(cc0’)
++
1
(cc1’)
(cc2’)
1+-
can it be a
++
1
cc state?
1++cc1’
(the only
possibility)
Bf(Xp+p- J/y)>4%
is very large for an
isospin-violating
channel
3872
p+p(Isospin
violating)
Expectations for c’c1
G(c’c1  g J/y)  11 keV
Barnes Godfrey PRD 69 054008
G(c’c1  p+p- J/y) = G(y’
?
 p0J/y)  0.3 keV
(“educated” guess?)
Expect:
Measmnt:
Bf(XgJ/y)
Bf(XppJ/y)
Bf(XgJ/y)
Bf(XppJ/y)
 30 ~ 40
>200x discrepancy
=0.14 ± 0.05
can our “education”
really be this bad?
cc1’ component of X(3872) is  few%
(at most?)
Intriguing fact
MX3872 =3872 ± 0.6 ± 0.5 MeV
mD0 + m D0* = 3871.2 ± 1.0 MeV
lowest mass
lowest mass spin=1
charmed meson
charmed meson
Deuson? deuteron-like DD* bound state?
c
Du
p
D*u
c
one p exchange
attractive for 1++
2 loosely bound
qq color singlets with
M = mD + mD* - d
Tornqvist PLB 590, 209 (2004)
X(3872) = D0D*0 bound state?
• JPC = 1++ is favored
• M ≈ mD0 + mD0*
Tornqvist PLB 590, 209 (2004)
• Large isospin violation is natural (&

|D0D*0> =
1/2(|10>
was predicted):
- |00>)
Equal mixture of I=1 & I =0
Swanson PLB 588, 189 (2004)
•
G(XgJ/y) < G(XppJ/y) was predicted
•
G(XD0D0p0) too large?
Swanson PLB 598, 197 (2004)
• Bf(B0K0X3872)/Bf(B+K+X3872) too large?
Braaten & Kusunoki PR D71, 074005 predict:
BaBar measurement (hep-ex/0507090):
<0.08
0.5  0.3
diquark-antidiquark?
Maiani etal predict
a doublet of states
PRD 71,014028 (2005)
u c
Xu=
c u
B+K+Xu
BaBar
d c
Xd =
c d
B0K0Xd
BaBar
Maiani et al predict: DM = M(Xu) – M(Xd) = 8  3 MeV
BaBar (hep-ex/0507090) reports:
DM = 2.71.3 0.2 MeV
Are there others?
Is the X(3872) a one-of-a-kind curiousity?
or the 1st entry in a new spectroscopy?
Look at other B decays  hadrons+J/y:
BK h J/y
BK p J/y
BK w J/y
BK wJ/y in Belle
“Y(3940)”
M≈3940 ± 11 MeV
G≈ 92 ± 24 MeV
Mbc
Mbc
Mbc
M(wJ/y) MeV
S.K. Choi & S.L.Olsen et al.
(Belle), PRL94, 182002 (2005)
Y(3940): What is it?
• Charmonium?
eg.Brambilla et al (QWG) hep-ph/0412158
– Conventional wisdom: (SU(3)-violating) wJ/y
decay should not be a discovery mode for a
cc state with mass above DD & DD*
threshold!
•
cc-gluon hybrid?
– predicted by QCD, Horn & Mandula PRD 17 898
– decays to DD and DD* are suppressed
(“open-charm” thresh = mD + m
D**
= 4.3 GeV)
– large hadron+J/y widths can occur
– masses expected to be 4.3 ~ 4.4 GeV
(higher than what we see)
others
BaBar’s Y(4260)
e e  g ISR p p J /y
+ -
+
-
10.58 GeV
4.26 GeV
M=4259  8 MeV
G = 88  23 MeV
Y(4260)
J/y sideband
B. Aubert et al. (BaBar)
hep-ph/0506081
s(e+e-hadrons)
not seen in s(e+e-hadrons)
at Ecm =4.26 GeV
BES
J.Z. Bai et al. (BESII)
PRL 88 101802
Well above DD & DD* threshold but wide
& found in a suppressed mode??
summary
• X(3872):
– Existence well established
– JPC = 1++
– Br(Xp+p- J/y) too high for charmonium
– Br(XD0D0p0) too high for molecule
– Br(B0  KSX3872) also too high for molecule(?)
– DM too small for diquarks? still under study
(M(Xu)
(from B+K+Xu)
- M(Xd)
(from B0KSXd)
– Mass too low for hybrid
The more we learn more about it
the more puzzling it becomes.
summary (cont’d)
• Y(3940) Belle
– G( Y3940 wJ/y) too high for charmonium
– Mass too low for a hybrid
by factors of ~103
• Y(4260) BaBar
– G(y4260p+p-J/y) also way too high
– 1--, but not seen in e+e- hadrons
Homeless mesons
•X(3872)
•Y(3940)
•Y(4260)
•…
但願人長久
千里共嬋娟
Back-up slides
Baryonium at BES???
u d
u
u
d u
J/y  g pp (at BES)
Phys. Rev. Lett. 91, 022001 (2003)
acceptance
weighted BW
M(pp)
+3 +5
M=1859 -10 -25 MeV/c2
G < 30 MeV/c2 (90% CL)
0
3-body phase space
0.1
0.2
M(pp)-2mp (GeV)
0.3
Baryonium potential & Wave fcn
Potential
barrier
G.J. Dung & M.L. Yan hep-ph/0502127
“Rectangularized”
Skyrmion-type
potential
I = 0, Jpc=0-+
pp annihilation
M ~ 1860 MeV
G ~ 16 MeV
 large uncertainties
-V0d(r)
X  p+p- h’ should be a strong channel
M(p+p-h’) from J/y  g p+p-h’
p+p-h mass spectrum for
hp+p-h & h gr modes
7.7s
N obs  264  54
M = 183463 MeV
G = 68  20 8 MeV
BESII Preliminary
B( J y  gX ) B( X  p +p -h)  (2.2  0.4  0.4)  10-4
c. f . : B( J y  gX ) B( X  pp)  (7.0  0.4+-10..98 ) 10-5
_
Re-fit J/yg p p including FSI
M = 1830.6  6.7 MeV
I=0 FSI
Sirbirtsev et al. (PRD 71 054010 )
G = < 153 MeV @90%C.L.
M pp - 2mp
Appendix
• Other new hidden charm particles from
Belle (near 3940!)
– X(3940)
– Z(3931)
Other new particles from Belle
e+e-J/y + X
X(3940)DD* seen
(DD & wJ/y not seen)
gg  Z(3931) DD at Belle
sin4q (J=2)
41 11 evts (5.5s)
M=3931  4  2 MeV
G208 3 MeV
Z(3931) = cc1’ (almost for sure)
?
X(3940)  Y(3940)
(maybe the hc’’)
Jon Coleman
Moriond-QCD
March 2005
e+e-B+B244 fb-1
K-X0
Can measure absolute
B.F.’s of B-K-X0
Lower limit on
BF(XJ/ypp) > 4.3%
@ 90% C.L
J/y
cc2 cc1
cc0
• cc2,cc0<<cc1
•X(3872) production much lower than for other
Charmonium states:
•can set lower limit on B.F.
Very clear J/y and
hc signals
N J/y=258+- 42
N hc =266 +-42
Kinematic variables
BK gJ/y
Ecm/2
e+
e-
ϒ(4S)
Ecm/2
DE
CM energy difference:
DE  EK + EgJ /y - Ecm / 2
BK gJ/y
Beam-constrained mass:
mbc  ( ECM


2) - ( pK + pgJ /y ) 2
2
Mbc
++
1
1++: sin2ql sin2c
compute angles in
X(3872) restframe
c2/dof = 11/9
ql
K
c
1++ looks okay!
|cosql|
c2/dof = 5/9
|cosc|
M(gJ/y) look-back plot
Fit cosqlp with 1++ MC
c2/dof=11.9/9
|cosqlp|
Y(3940): What is it
•
a molecule?
– M ≈ 2mDs
– not seen in YhJ/y
• (h contains ss)
??
PRL 93, 041801
M(h J/y)
– width too large??
– no p exchange for DSDS
(cont’d)?
c
s
c s
Y(3940): What is it
•
(cont’d)
cc-gluon hybrid?
– predicted by QCD,
– decays to DD and DD* are suppressed
(“open-charm” thresh = mD + m
D**
= 4.3 GeV)
– large hadron+J/y widths can occur
– masses expected to be 4.3 ~ 4.4 GeV
(higher than what we see)
c
c
Horn & Mandula PRD 17 898 (1978) + (many) others
?