Transcript Searching for new forms of hadronic matter 武汉 &

Wuhan
武汉
10/15/07
Searching for new forms
of hadronic matter
Stephen L. Olsen
University of Hawai’i
& 高能物理所 北京
History:
(sub-atomic
particles)
1932: proton & neutron
..all we need???
Joliet-Curie
1937: muon
“Who ordered that?”
Rabi
1947: pion
predicted in 1935
Yukawa
Fermi
1950’s: ,,,,,…
“Had I foreseen that, I would have
gone into botany” – Fermi
Peters
Jones
Ting
chadwick
Hadron “zoo”
mesons
baryons
Constituent Quark Model: 1964
3 quarks
Gell-Mann
(& 3 antiquarks)
u+2/3
Zweig
d-1/3
u-2/3
s-1/3
Baryons: qqq
p:
p:
u+2/3 u+2/3
d-1/3
u-2/3 u-2/3
d+1/3
d+1/3
s+1/3
Mesons: q q
 +:
-:
u+2/3
d+1//3
u-2/3
d-1/3
Constituent Quark Model: 2007
6 quarks
u+2/3
d-1/3
c+2/3
t+2/3
s-1/3 b-1/3
Baryons: qqq
W c:
W c:
c+2/3 s+1/3
s-1/3
C-2/3 S=1/3
s+1/3
(& 6 antiquarks)
u-2/3 c-2/3
d+1/3
t-2/3
+1/3
s+1/3 b
Mesons: q q
u+2/3
+
B :
b+1//3
B- :
u-2/3
b-1/3
Fabulously successful at bringing
order to the hadron “zoo”
mesons
q
q
baryons
q
q
q
Fabulously successful, but…
• Why are isolated quarks are not seen?
• why only qqq and qq combinations?
• What about spin-statistics?
W-
s-1/3 s-1/3
s-1/3
three s-quarks
in the same
quantum state
禁止
The “charge” for the strong force
is a 3-dim spinor
Each quark can have 3 different “color” charges
Y. Nambu
Ws-1/3 s-1/3
s-1/3
the 3 s-1/3 quarks in the
W- have different color
charges & evade Pauli
O. Greenberg
QCD: Gauge theory
for color charges
Yang
Mills
Nambu
Fritzsch & GellMann
generalization of QED
QED
scalar charge: e
QED gauge Xform
+ieA
1 vector
field
(photon)
QCD
triplet charge:
QCD gauge Xform
er
eb
eg
   + i a l i Gi
eight 3x3 SU(3)
matrices
8 vector
fields
(gluons)
Attractive configurations
eijk eiejek
i≠ j≠k
dij ei ej
same as the rules for combining colors to get white:
add 3 primary colors
or add color+complementary color
quarks: eiejek  color charges
antiquarks: ei ej ek  anticolor charges
Hence the name: Quantum Chromodynamics
Difference between QED & QCD
QED: photons have no charge
QCD: gluons carry color charges
gluons interact with each other
a
Coupling strengths
distance
Test QCD with 3-jet events
(& deep inelastic scattering)
as
gluon
dist
Energy
rate for 3-jet events should
decrease with Ecm
“running” as
Winners of the
2004 Nobel Prize
Running as tests QCD at short
distances only
a
The long-distance regime,
where the matter we are
made of exists, remains
untested.
distance
Are there other color-singlet
arrangements?
Non-quark model states expected in QCD
Pentaquarks:
e.g. an S=+1 baryon
u d
u
d s
(only anti-s quark has S=+1)
Glueballs:
gluon-gluon color singlet states
Multi-quark mesons:
qq-gluon hybrid mesons
u c
c u
c
c
Spring8 electron Ring in Japan
A pentaquark?
g + n  K- K+ n
Q+(1530)?
S=+1 baryon:
impossible
with only qqq
u+2/3
s
u+2/3d-1/3
d-1/3
+1//3
M(K+n)
T.Nakano et al (LEPS) PRL 91 012002 (2003)  742 citations!!
Experimental situation is messy
(some contradictory experiments)
γp  Ks K n
+
Counts/4 MeV
SAPHIR (2004)
4.8
CLAS (2005)
Same reaction
M(nK+)(GeV)
Some groups contradict themselves
gd+K-K+n
CLAS-D (2005)
CLAS-D (2003)
5.2
???
no signal
Pentaquark Scoreboard
Positive signals
Negative results
Also: Belle
Compass
L3
CLAS
Yes: 17
No: 18
Status in 2006
“The conclusion that
pentaquarks in general, and the
Q+ in particular, do not exist,
appears compelling.”
-
George Trilling LBL
This is a risky business
You never know if nature
is smiling at you
or something else
Another approach: look for non-qq
mesons
4 (& 6) quark states
u u d
d u u
u c
c u
“hybrid” qq-gluon states
c
c
theory:
mc2>4.2 GeV
The Beijing Electron Positron
Collider (BEPC)
高能物理研究所
e+
e-
Beijing Spectrometer (BES)
e+e- annihilation cross section
BES Energy Range
ss
cc
q
bb
q
Ecm(GeV)
J/y  g pp
g
c+2/3
C-2//3
p
d
u u
u
d u
p
J/y  g pp
What is this???
BESII
This is the hcpp
the J/y’s well
known S=0 partner
J.Z. Bai et al. (BESII)
PRL 91 022001 (2003)
M(pp) GeV
Fit the M(pp) distribution
Best fit to this peak
is a resonance with
peak mass below the
pp mass threshold
M=1830.6 ± 6.7 MeV/c2
< 153 MeV/c2 (90% CL)
matches to no known state.
A pp bound state (baryonium)?
There is lots & lots of literature about this possibility
deuteron:
baryonium:
attractive nuclear force
p
n
loosely bound
3-q 3-q color
singlets with
Md = 2mp- e
attractive force?
p
p
loosely bound
3-q 3-q color
singlets with
Mb = 2mp-d ?
An old idea
Fermi & Yang in 1949
(7 years before p discovery):
If NN potential is attractive, they
could bind to form -like states.
Expectation for pp bound
state meson
below-threshold
p and p
annihilate to
mesons
I=0, JPC=0-+ init. state:
pp  +-h’ is common
Ding & Yan Phys.Rev.C72:015208,2005.
Above threshold
Xpp ~100%
mp +mp
BES looked at J/y  g +-h’
BESII
mp+mp
These values match
those for the pp peak
(as predicted by Ding&Yan)
M=1833 MeV
  70MeV
M(+-h’)
M. Ablikim et al. (BESII)
PRL 95, 262001 (2005)
X(1835): a“6-quark” meson?
d u
u
u u
d
3 quarks
+
3 antiquarks
•Need to confirm JPC of the +-h’ peak is 0-+
•Need to find it in other common 0-+ pp
annihilation channels
job for BESIII
Move over to Japan
Tsukuba Mountain
KEKB Collider
KEK laboratory
International Collaboration Belle
e+e- annihilation cross section
KEK B-factory
ss
cc
q
bb
q
Ecm(GeV)
B meson decays
C+2/3
b-1/3
“Charmonium”
C-2/3
u-2/3
S-1/3
u-2/3
K-
Primer on
Charmonium
Charmonium
mesons formed from c- and c-quarks
c
r
c
c-quarks are heavy: mc ~ 1.5 GeV  2mp
velocities small: v/c~1/4
non-relativistic QM applies
QM of cc mesons
c
r
c
2

2
  + V (r )  E
2mr
What is V(r) ??
“derive” from QCD
quantum chromodynamics
“Cornell” potential
c
r
~0.1 fm
c
slope~1GeV/fm
“confining”
large distance
component
V(r)
G.S.Bali
hep-ph/0010032
2 parameters:
slope & intercept
1/r “coulombic”
short distance
component
Charmonium spectrum
y’’
y’
hc’
hc
hc
cc0,1,2
J/y
All of these states
are well established
Study
+
BK   J/y
+
J/y
C+2/3
b-1/3
C-2/3
u-2/3
S-1/3
u-2/3
K-
The X(3872)
BK +-J/y
y’+-J/y
X(3872)+-J/y
M(J/y) – M(J/y)
S.K. Choi et al PRL 91, 262001
Its existence is well established
seen in 4 experiments
CDF
9.4
11.6
X(3872)
D0
X(3872)
Is it a cc meson?
Could it be
one of these?
3872 MeV
These states
are already
identified
The JPC quantum numbers
++
of the X(3872) are 1
From studying different decay processes
& angular correlations among decay products
can it be the
1++cc1’
++
1
cc state?
23P1 cc state
(the only
charmonium
possibility)
M=3872 MeV is low,
3872
g
+Allowed
(Isospin E1
transition
violating)
X+- J/y decay
is a forbidden decay
Intriguing fact
MX3872 =3871.2 ± 0.5 MeV
mD0 + m D0* = 3871.6 ± 0.4 MeV
lowest mass
lowest mass spin=1
charmed meson
charmed meson
Deuson? deuteron-like DD* bound state?
c
Du

D*u
c
one  exchange
attractive for 1++
2 loosely bound
qq color singlets with
M = mD + mD* - d
Tornqvist PLB 590, 209 (2004)
Braaten et al, PRL 93, 162001
Another old idea
DeRujula, Georgi,Glashow, PRL 38, 317 (1977)
X(3872)??
X(3872) summary
–
–
–
–
Existence well established
JPC = 1++
Br(X+- J/y) too high for charmonium
Mass too low for hybrid
Four years after discovery, theorists
are still puzzling over what it may be
Next, California
Stanford Linear
Accelerator Ctr
BaBar Detector
Radiative return
B-factory
energies
ss
cc
bb
10.58 GeV
3~5
GeV
Ecm(GeV)
Y(4260)
e e  g ISR   J /y
+ -
+
-
10.58 GeV
4.26 GeV
M=4259  8 MeV
 = 88  23 MeV
Y(4260)
J/y sideband
B. Aubert et al. (BaBar)
PRL 95 142001 (2005)
(e+e-hadrons)
not seen in (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??
a
-1
cc slot for the Y(4260)?
X.H. Mo et al, hep-ex/0603024
4260
J.Z. Bai et al. (BESII)
PRL 88 101802
4260
Theorist’s favorite
interpretation
“hybrid” qq-gluon states
c
c
just about the right mass for theory
D1D D D
2
A +-y’ peak at 4325MeV
e+e-gISR +- y’
298 fb-1 (BaBar) hep-ex/0610057
Nevt = 68 (<5.7 GeV/c2)
Nbkg = 3.1 1.0
M=4324  24 MeV
 = 172  33 MeV
Not Compatible with the Y(4260)
BaBar PRL 98 252001 (2007)
S.W.Ye QWG-2006 June 2006
c2-prob
< 5.7 GeV/c2
Y(4260)
6.5 10-3
y(4415)
1.2 10-13
Y(4320)
29%
New results on the +-y’ peak
from Belle
It is really two peaks!
M=4361  9 ±9 MeV
(both relatively narrow)
(neither one consistent with 4260)
 = 74  15 ±10 MeV
4260
M=4664  11 ±5 MeV
 = 48  15 ±3 MeV
X.L. Wang et al (Belle)
arXiv:0707.3699
548 fb-1
Need 2 more 1-- cc slots for
Y(4630) & Y(4660)
X.H. Mo et al, hep-ex/0603024
4660
4360
4260
4260
Excited hybrid states?
c
c
Latest News
±
M( y’)
from BK
±

y’
M = 4433 ±4 ±1 MeV
tot = 45
+17 +30
-13 -11
MeV
Nsig =124 ± 31evts
6.5
M(y’) GeV

K. Abe et al (Belle)
arXiv:0708.1790
Can’t be a cc meson or a hybrid
4660
4360
4260
No charged cc hybrid states
C+2/3
C-2/3
gluons have zero charge
Summary
Mesons with no qq assignment:
X(1835)
Y(4260)
BESII
X(3872)+-J/y
M(J/y)
M(pp) GeV
M(J/y) – M(J/y)
Y(4360)
Y(4660)
Y(3940)
±(4430)
Z
M(wJ/y) MeV
548 fb-1
M(y’) GeV
Concluding remarks
• A number of “mysterious” mesons that don’t fit into
the simple quark model picture have been found
• If they are related to each other, these particles
can’t be the hybrid states predicted by QCD
• Are these curiosities, each with its own story?
… or are they 1st signs of a spectroscopy of new
forms of hadronic matter?
• Hopefully, time, & more experimentation, will tell
謝謝
Thank you
Back-up slides
Conclusion
• either:
– The constituent quark model for mesons
needs major revision
• or:
– There is a new, non-qq, hadron
spectroscopy, maybe more than one.
Difference between QED & QCD
QED:
QCD:
photons have no charge
gluons carry color charges
gluons interact with each other
Vacuum polarization QED vs QCD
2nf
11CA
in QCD: CA=3, & this dominates
The LEPS observation of Q+(1530)
Q+(1530)
n
g + n  K- Q+n K- K+ n
g+ n 
K-
K+
n
M(K+ n)
u+2/3
s
Physical Review Letters, 91, 012002 (2003)
u+2/3d-1/3
d-1/3
+1//3
S=+1
Charmonium state?
(e+e-hadrons)
No sign of it (e+e-hadrons)
at Ecm =4.26 GeV
BES
J.Z. Bai et al. (BESII)
PRL 88 101802
4260
fitted peak
location
Actual fit
J/ygpp in the BES expt
M=1830.6 ± 6.7 MeV/c2
 < 153 MeV/c2 (90% CL)
c2/dof=56/56
0
0.1
0.2
0.3
A pp bound state (baryonium)?
There is lots & lots of literature about this possibility
deuteron:
baryonium:
attractive nuclear force
p
attractive force?
E. Fermi, C.N. Yang, Phys. Rev. 76, 1739 (1949)
n
p
p
!!!
Y.Nambu, G. Jona-Lasinio Phys Rev 122, 345 (1961)
…
I.S. Shapiro, Phys. Rept. 35, 129 (1978)
C.B. Dover, M. Goldhaber, PRD 15, 1997 (1977)
…
A. Datta, P.J. O’Donnell, PLB 567, 273 (2003)]
M.L. Yan et al., hep-ph/0405087
B. Loiseau et al., hep-ph/0411218
loosely bound
3-q 3-q color
singlets with
…
Md = 2mp- e
loosely bound
3-q 3-q color
singlets with
Mb = 2mp-d ?
The X(3872)
Study +-J/y produced in BK +- J/y decays
????
hadronic molecules
a new spectroscopy?
may be more particles to find
summary
• X(1835):
– Existence well established
– JPC = 0-+
– Br(Xpp) too high for qq meson
– X+-h’ is expected for sub-thresh pp state
0++
eeJ/y
0-+
k(exeJ/y)
Ruled out by Belle
ql
y
c2/dof=34/9
c2/dof = 34/9
|cosq|
|cosql|
rule out 0++ & 0 -+
|cosy|
C=+1 is established
X(3872)gJ/y seen in:
M() looks like a 
CDF
PRL 96 102002
Belle
hep-ex/0505037
&
Belle
X(3872)”w”J/y seen
Belle
Angular analysis from CDF
CDF Collab. PRL 98, 132002 (2007)
1++
or
2-+
Use Angular Correlations to
determine J & P
+-
Jz=0
X3872
z
Rosner (PRD 70 094023)
Bugg (PRD 71 016006)
Suzuki, Pakvasa (PLB 579 67)
J=0
J=0
K
J/ym+m- (e+e-)
Possible JPC values
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+-
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)
•
(XgJ/y) < (XJ/y) was predicted
•
(XD0D00) 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
Y(3940) in BK wJ/y
Belle PRL94, 182002 (2005)
M2(wJ/y) GeV2
M≈3940 ± 11 MeV
≈ 92 ± 24 MeV
M2(Kw) GeV2
M(wJ/y) MeV
If not charmonium, what?
c
c
“hybrid” cc-gluon state?
But why does it decay to +- J/y,
and not to D and D* mesons?
Y(4260) summary
–
–
–
–
Existence well established
JPC = 1-(X+- J/y) too high for charmonium
Br(XD(*)D(*)) too low for hybrid
Another mystery!!
J/y  g pp
g
p
c+2/3
C-2//3
u+2/3 u+2/3
d-1/3
p
u-2/3 u-2/3
d+1/3