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History:(sub-atomic
particles)
1932: proton & neutron
..all we need???
1937: muon
“Who ordered that?”
1947: pion
predicted in 1935
1950’s: ,,,,,…
“Had I foreseen that, I would have
gone into botany” – Fermi
chadwick
Fermi
TingPeters Jones
Rabi
Yukawa
Joliet-Curie
Quarks restore economy(& rescue future Fermis from Botany?)
(& 3 antiquarks)
Mesons: q q
p: u+2/3
p: u-2/3
+: d-1/3
u+2/3
d+1/3
u-2/3
u-2/3
d+1//3
u+2/3
-: u+2/3
u-2/3
d+1/3 s+1/3
u+2/3
d-1/3 s-1/3
Gell-Mann3 quarks
Zweig
Baryons: qqq
Fabulously successful, but…
• quarks are not seen
• why only qqq and qq combinations?
• What about spin-statistics?
The strong interaction “charge” of each quark comes
in 3 different varietiesY. Nambu
O. Greenberg
s-1/3
s-1/3
s-1/3
the 3 s-1/3 quarks in the- have different colorcharges & evade Pauli
-
QCD: Gauge theory for color charges
generalization of QED
+ i e A + i i Gi
QED gauge Xform
QCD gauge Xform
eight 3x3 SU(3) matrices
8 vectorfields
(gluons)
1 vectorfield
(photon)
scalar charge: eisotriplet charge:
er
eb
eg
QED QCD
Yang MillsNambu
Fritzsch & GellMann
Attractive configurations
ijk eiejek
i ≠ j ≠ k
ij ei ej
same as the rules for combining colors to get white:
add 3 primary colors or add color+complementary color
antiquarks: anticolor charges
Hence the name: Quantum Chromodynamics
quarks: eiejek color charges
ejei ek
Difference between QED & QCD
QED: photons have no charge
QCD: gluons carry color chargesgluons interact with each other
Coupling strengths
distance
Test QCD with 3-jet events(& deep inelastic scattering)
rate for 3-jet events should decrease with Ecm
gluons
Probe QCD from other directions
Proposed non-qq or non-qqq hadron spectroscopies:
Pentaquarks:e.g. an S=+1 baryon
(only anti-s quark has S=+1)
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
CDF
but not seen in just as many others
High interest:1st pentaquark paperhas ~500 citations
Belle
BES
Experimental situation is messy(some contradictory experiments)
SAPHIR (2004)4.8
M(nK+)(GeV)
Cou
nts
/4 M
eV
nKKγp s
CLAS (2005)
Same reaction
Plenary speaker at LP05
“The pentaquark is not in good health, but it is still
alive.” -
Volker D Burkert Jefferson Lab
This talk: 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)
Charmonium
r
mesons formed from c- and c-quarks
c-quarks are heavy: mc ~ 1.5 GeV 2mp
velocities small: v/c~1/4
non-relativistic QM applies
c c
“Cornell” potential
~0.1 fm
G.S.Bali hep-ph/0010032
“confining”large distance
component
slope~1GeV/fm
1/r “coulombic”short distance
component
c cr
V(r)
2 parameters:slope & intercept
1-- Charmonium states
J/’
D-meson + anti-D meson mass threshold
”
“narrow”(~100KeV)
e+
e-
Directly accessible via e+e- annihilation
(e+e-hadrons)
“narrow”(~300KeV)“wide”(~25 MeV) ” DD decay
channel is openDD)25MeV
P-wave states Gamma energy spectrum from ’ X decays
Gaiser et al (Crystal Ball) PRD 34 711
accessible via E1 transitions from ’
23S1 (’)13P2 (c2) 17 keV
23S1 (’)13P1 (c1) 24 keV
23S1 (’)13P0 (c0) 24 keV
13P2 (c2) 13S1(J/) 420 keV
13P1 (c1) 13S1(J/) 290 keV
13P0 (c0) 13S1(J/) 120 keV
E1 Transition Partial width
Calculable from”1st prin
ciples”
Good agreement with
measurements
Hadronic transitions
(’J/) 70 keV“allowed”
(”J/) 50 keV“allowed”
(’J/) 5 keVSUF(3) violating
(’J/) 0.3 keVisospin violating
“reasonable” agreement between
measurement & th
eory
c.f. Kuang & Yan PRD 41 155
Recent results
13D1 13P1seen by CLEO hep-ex/0509030
(meas) = 75 18 keV(theor) 59~77 keV
11P1 found by CLEOhep-ex/0508037properties as expected
23P2 found by Bellehep-ex/0507033properties as expected
21S0 found by BelleS.K.Choi et al PRL 89 102001
properties as expected
Its existence is well established
seen in 4 experiments
X(3872)
CDF
X(3872)
D0
hep-ex/0406022
9.411.6
no obvious cc assignment
3872
c”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
hc’
c1’
2
2
3
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
Strong evidence for C=+1
13.6 ± 4.4 X(3872)J/evts (>4significance)
X(3872)J/
virtual (782)?
X(3872)J/
Bf(XJ/)
Bf(XJ/)=0.14 ± 0.05
Br(X3J/)Br(X2J/) = 1.0 ± 0.5
M()
M()
X(3872)J/
Fits to (760)
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/ee
J=0J=0X3872
Jz=0
z
Rosner (PRD 70 094023)
Bugg (PRD 71 016006)
Suzuki, Pakvasa (PLB 579 67)
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
X(3872) D0D00 ?
11.3±3.6 sig.evts (>4)
Bf(BKX)Bf(XDD)=2.2±0.7±0.4x10-4
D*0D00?
M(D0D00)
• 1++ : DD* in an S-wave q*
• 2++ : DD in a D-wave q*5
Strong threshold suppression
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++
can it be a 1++ cc state?
1++c1’(the only possibility)
3872
Bf(XJ/)>4%is very large for an isospin-violating
channel(Isospin
violating)
M=3872 MeV is too low, especially now that we know that M(c2’)=3931 4
MeV
Expectations for ’c1
(’c1 J/) 11 keV Barnes Godfrey PRD 69
054008
(’c1 J/) = ? (’ J/) 0.3 keV (“educated” guess?)
Bf(XJ/)
Bf(XJ/) 30 ~ 40
Bf(XJ/)
Bf(XJ/)=0.14 ± 0.05
Expect:
Meas:
>200x discrepancy
c1’ component of X(3872) is few% (at most?)
can our “education” really be this
bad?
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
D D*
2 loosely bound qq color singlets
with M = mD + mD* -
u
cu
c
one exchangeattractive for 1++ Tornqvist PLB 590, 209 (2004)
Deuson? deuteron-like DD* bound state?
X(3872) = D0D*0 bound state?
• JPC = 1++ is favored
• M ≈ mD0 + mD0*
• Large isospin violation is natural (& was predicted):
|D0D*0> = 1/2(|10> - |00>)
• (XJ/) < (XJ/) was predicted
• (XD0D00) too large?
• Bf(B0K0X3872)/Bf(B+K+X3872) too large?
Equal mixture of I=1 & I =0
Swanson PLB 598, 197 (2004)
Tornqvist PLB 590, 209 (2004)
Swanson PLB 588, 189 (2004)
Braaten & Kusunoki PR D71, 074005 predict: <0.08BaBar measurement (hep-ex/0507090): 0.5 0.3
diquark-antidiquark?
Maiani et al predict: M = M(Xu) – M(Xd) = 8 3 MeV
BaBar (hep-ex/0507090) reports: M = 2.71.3 0.2 MeV
u cuc
d cdc
Maiani etal predicta doublet of statesPRD 71,014028 (2005)
Xu= Xd=
B+K+Xu B0K0Xd
BaBar BaBar
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 & S.L.Olsen et al.(Belle), PRL94, 182002 (2005)
M(J/) MeV
Y(3940): What is it?
• Charmonium?– Conventional wisdom: (SU(3)-
violating) J/decayshould not be a discovery mode for a cc state with mass above DD & DD* threshold!
eg.Brambilla et al (QWG) hep-ph/0412158
• 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 can occur– masses expected to be 4.3 ~ 4.4 GeV
(higher than what we see)
Horn & Mandula PRD 17 898 others
/ISR Jee
J/ sideband
Well above DD & DD* threshold but wide & found in a suppressed
mode??
M=4259 8 MeV = 88 23 MeV
B. Aubert et al. (BaBar)hep-ph/0506081
Y(4260)
10.58 GeV
4.26 GeV
not seen in (e+e-hadrons)at Ecm =4.26 GeV
J.Z. Bai et al. (BESII)PRL 88 101802
BES
BaBar’s Y(4260)
(e
+e
- h
ad
ron
s)
summary• X(3872):
– Existence well established– JPC = 1++
– Br(X J/) too high for charmonium– Br(XD0D00) too high for molecule
– Br(B0 KSX3872) also too high for molecule(?)
– M too small for diquarks?
– Mass too low for hybrid
by a factor o
f
more than 200!
still under study
The more we learn more about it the more puzzling it
becomes.
(M(Xu) (from B+K+Xu) - M(Xd) (from B0KSXd)
other odd-balls
• Y(3940) Belle– ( Y3940 J/too high for charmonium
– Mass too low for a hybrid
• Y(4260) BaBar– (y4260J/also way too high
– 1--, but not seen in e+e- hadrons
by factors of ~103
Conclusion
• either:– The “standard model” for
charmonium mesons needs major revision
• or:– There is a new hadron spectroscopy
in the 3.5~4.5 GeV mass region
Opportunities for CLEO-c & BES-III ???
Xu – Xd Mass difference?:
MXu – M’ = 185.7 0.6 MeV
MXd – M’ = 184.0 1.3 MeV
M(Xu) – M(Xd) = 0.8 1.4 MeV
Belle:
Preliminary
Another one?
• e+e- J/ + X
>4)peak at M=394011 MeVN=14833 evtsWidth consistent w/ resolution
(= 32 MeV)
c
cc0
c‘
‘
What is it? c0 ? c ?? ‘ “