non-standard mesons stephen l. olsen university of hawai’i representing belle fermilab seminar may...
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Non-standard mesonsStephen L. Olsen University of Hawai’i
Representing Belle
Fermilab seminar May 10, 2005
Probe QCD from other directions
non-qq or non-qqq hadron spectroscopies:
Pentaquarks:e.g. an S=+1 baryon
Glueballs:gluon-gluon color singlet states
Multi-quark mesons:
qq-gluon hybrid mesons
u cuc
c c
ud
usd
Pentaquarks?“Seen” in many experiments
BaBar
High interest:1st pentaquark paperhas ~500 citations
BelleBES
but not seen in just as many others
CDF
Compass
Jlab p
Pentaquark Scoreboard
Positive signals Negative results
Also: Belle Compass L3 Jlab(CLAS) (pK+Ksn)
Yes: 17 No: 18
Angular analysis for B D DsJ
DsJDs()
J=1
J=0
DsJ(2317) Ds0
J=1
J=2
DsJ(2460) Ds
zJz=0
DsJ(2317) = 0+
DsJ(2547) = 1+
J=0
DsJ states are likelyordinary L=1 cs
mesons(with perhaps some tetraquark
mixture)
Potential models got the masses wrong
Chiral models seem to work OKSee, e.g. Bardeen, Eichten & Hill PRD68, 054024
non-standard mesons with “hidden charm”
• standard cc mesons are:– best understood theoretically– narrow & non overlapping
• c + c systems are commonly produced in B meson decays.
b
cc
s
Vcb
cosC
CKM favored
W-
c c
u cuc (i.e containing c & c)
Its existence is well established
seen in 4 experiments
X(3872)
CDF
X(3872)
D0
hep-ex/0406022
9.411.6
PRL 93, 072001
PRL 93, 162002
PRD 71, 071103(R)
no obvious cc assignment
3872
c”
hc’
c1’
2
c2
3
M too low and too small
angular dist’n rules out 1
J/ way too small
c too small;M() wrong
c& DD) too small
c should dominate
SLO hep-ex/0407033
JPC possibilities (for J ≤ 2)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
JPC possibilities0-- ruled out; JP=0+,1- & 2+ unlikely
0--
exotic
violates parity 0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
Areas of investigation
• Search for radiative decays
• Angular correlations in XJ/ decays
• Fits to the M() distribution
• Search for X(3872)D0D00
Kinematic variables
CM energy difference:
Beam-constrained mass:
2/
2 )()2( JKCMbc ppEm
BK J
BKJ2// cmJK EEEE
B
Bϒ(4S)
Ecm/2
e e
Ecm/2
Mbc
E
Select BK J/BKc1; c1J/
X(3872)?
13.6 ± 4.4 X(3872)J/evts (>4significance)
M(J/)
Bf(XJ/)
Bf(XJ/)=0.14 ± 0.05
Mbc Mbc
Evidence for X(3872) J/reported last summer hep-ex/0408116)
B-meson yields vs M()
Br(X3J/)Br(X2J/)
= 1.0 ± 0.5 Large (near max)Isospin violation!!
A virtual (782)?
12.4 ± 4.2 evts
M() MeV
C=+1 is established
• X J/ only allowed for C=+1• same for X””J/ (reported earlier)• M() for XJ/ looks like a
CDF
JPC possibilities (C=-1 ruled out)
0--
exotic
Violates parity 0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S)) 1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2) 2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
Angular Correlations
K
J/J=0
J=0X3872
Jz=0
z
Rosner (PRD 70 094023)
Bugg (PRD 71 016006)
Suzuki, Pakvasa (PLB 579 67)
Use 253 fb-1 ~275M BB prs
exploit the excellent S/N
Signal(47 ev)Sidebands
(114/10 = 11.4 ev)
XJ/’J/
Example: 1--
dN/dcos sin2K
K
compute angles inJ/ restframe
D.V. Bugg hep-ph/0410168v2
’2/dof = 8.9/9
Use BK ’
’ is 1--
K
J/’
z
|cosKl| for X(3872) events
X(3872) is not 1-- !
expect 2~3evts/bin
backgroundscaled fromsidebands
fit withsin2Kl + bkgd
2/dof = 60.3/9 see 8 evts/bin
0++
l
In the limit whereX(3872), , & J/rest frames coincide:
d/dcosl sin2l
rule out 0++
|cosl|
2/dof = 34/9
M J/ ·
1++
l
dN/dcosdcos sin2l sin2
K
1++ looks okay!
|cosl|
2/dof = 11/9
|cos|
2/dof = 5/9
compute angles inX(3872) restframe
M | X x J/ x
JPC possibilities (0-+ & 0++ ruled out)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S)) 1-+
exotic
DD allowed
1++
(c1’)
1+-
(hc’)
2- -
(2) 2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
M() can distinguish -J/ S- & P-waves
S-wave: 2/dof = 43/39 P-wave: 2/dof = 71/39
q*roll-off
q*3
roll-off
(CL=0.1%)(CL= 28%)
Shape of M() distribution nearthe kinematic limit favors S-wave
Possible JPC values (J-+ ruled out)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2) 2++
DD allowed
c2’)
2+-
exotic
DD allowed
Select BK D0D00 events
|E| |E|11.3±3.6 sig.evts (5.6)
Bf(BKX)Bf(XDD)=2.2±0.7±0.4x10-4
Preliminary
D*0D00?
M(D0D00)
X(3872)DD rules out 2++
• 1++ : DD* in an S-wave q*
• 2++ : DD in a D-wave q*5
Strong threshold suppression
Eliminate all other factors and
the one which remains must be
the truth
Sherlock HolmesThe Sign of Four
Possible JPC values (2++ ruled out)
0--
exotic
violates parity
0-+
(c”)
0++
DD allowed
(c0’)
0+-
exotic
DD allowed
1- -
DD allowed
((3S))
1-+
exotic
DD allowed1++
(c1’)
1+-
(hc’)
2- -
(2)
2- +
(c2)
2++
DD allowed
c2’)
2+-
exotic
DD allowed
1++1++
can it be a 1++ cc state?
1++ c1’– Mass is ~100 MeV off
– c1’ J/ not allowed by isospin.
Expect: Bf(c1’J/)<0.1%
BaBar measurement: Bf(XJ/)>4%
3872
-(c1’J/) / (c1’J/)
Expect: ~ 40(X3872J/) / (X3872J/)
Measure: 0.14 ± 0.05
c1’ component of X(3872) is ≤ few%
• c2,c0<<c1•X(3872) production much lower than for other Charmonium states:•can set lower limit on B.F.
Can measure absolute B.F.’s of B-K-X0
e+e-B+B-
K-X0
Lower limit on BF(XJ/) > 4.3% @ 90% C.L
244 fb-1
Very clear J/ and c signals N J/=258+- 42N c =266 +-42
c2 c1 c0
J/
Jon ColemanMoriond-QCDMarch 2005
From BaBar: D(*)+ fully reconstructed
Intriguing fact
MX3872 =3872 ± 0.6 ± 0.5 MeV
mD0 + m D0* = 3871.2 ± 1.0 MeV
lowest masscharmed meson
lowest mass spin=1charmed meson
X(3872) is very near DD* threshold.is it somehow related to that?
D0D*0 bound state (deuson)?
p n D D*
deuteron:
2 loosely bound qqq
color singlets with Md = mp+mn-
deuson:
2 loosely bound qq color
singlets with M = mD + mD* -
attractive nuclear force attractive force??
Tornqvisthep-ph/0308277
uc
u
c
Voloshin & Okun JETP Lett 23, 333 (1976)Bander et al PRL 36, 695(1976)DeRujula et al PRL 38, 317 (1977)Manohar & Wise, NP B339, 17 (1993) Tornqvist, Z Phys C61, 525(1994)
X(3872) = D0D*0 bound state?
• JPC = 1++ is favored
• M ≈ mD0 + mD0*
• Maximal isospin violation is natural (& was predicted): |I=1; Iz= 0> =1/2(|D+D*->+ |D0D*0>) |I=0; Iz= 0> =1/2(|D+D*-> - |D0D*0>)
|D0D*0> = 1/2(|10> - |00>)
• (XJ/) < (XJ/) was predicted
Equal mixture of I=1 & I =0
Swanson PLB 598, 197 (2004)
Tornqvist PLB 590, 209 (2004)
Swanson PLB 588, 189 (2004)
X(3872) conclusion
•JPC = 1++
•cc content is small
•matches all(?) expectations for a D0D*0 bound state
C C
u cuca non-qq meson
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/
BK J/
BK J/
BK J/
BK J/ in Belle
“Y(3940)”M≈3940 ± 11 MeV≈ 92 ± 24 MeV
Mbc Mbc Mbc
S.K. Choi et al hep-ex/0408126to appear in PRL
Bf(BKY)Bf(YJ/)=7.1±1.3±3.1x10-5
Y(3940): What is it?
• Charmonium?– Conventional wisdom: J/ should not be
a discovery mode for a cc state with mass above DD & DD* threshold!
• Some kind of -J/ threshold interaction?– the J/is not surrounded by brown
muck; can it act like an ordinary hadron?
J/
Brambilla et al (QWG) hep-ph/0412158Eichten, Lane & Quigg PRD 64, 094019Barnes, Godfrey & Swanson hep-ph/0505002
Y(3940): What is it (cont’d)?
• another tetraquark?– M ≈ 2mDs
– not seen in YJ/• ( contains ss)
– width too large??– no exchange for DSDS
s csc
??PRL 93, 041801
M( J/)
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/ widths are predicted– masses expected to be 4.3 ~ 4.4 GeV
(higher than what we see)
c c
Horn & Mandula PRD 17 898 (1978)
Close PLB 342, 369 McNiele et al PRD 65
094505
Isgur et al PRL 54, 869 (1995)
Another one?
What is it? c0 ? c ?? ’ ”
c
c c0
‘
• e+e- J/ + X
>4)peak at M=394011 MeVN=14833 evtsWidth consistent w/ resolution
(= 32 MeV)
(e+e-)J/ c = 25.6 ±2.8 ± 3.4 fb)(e+e-J/ (cc))/(e+e-J/ X) = 0.82 ± 0.15 ± 0.14
Could this be the c”?strange Mn()-Mn(c) splitting pattern
M = 118 ± 3 MeV
M = 48 ± 5 MeV
M ~ 100 MeV??
(1S)
(2S)
(3S)4040
3686
3096
c
c
c
‘
“
decreases
then increases?
Could this be the c”?
(1S)
(2S)
(3S)4040
3686
3096
c
c
c
‘
“
D(*)D(*) coupling pushes (3S)up, increases the splitting
23S-13D1 mixing + DD coupling pushes (2S) down
splitting smaller
DD
DD*
D*D*
Probably O
K
Summary• X(3872):
– JPC established as 1++
– cc component is small (≤ few %)– all properties consistent with a D0D*0
bound state u cuc
a non-standard meson
c c?????
needs morestudy
• Y(3940):– No obvious cc assignment– tetraquark seems unlikely– cc-gluon hybrid?
• X(3940): – Probably the c”