Transcript Hidden charm spectroscopy from B-factories

ITEP Winter School 2012, Feb 18 2012
Quarkonium, experiment
Roman Mizuk
ITEP, Moscow
BELLE Collaboration
1
Contents
B-factories observed CP violation in B decays
Confirmed Kobayashi-Maskawa mechanism  Nobel prize 2008
Other highlights:
many rare B decays
D0 mixing
Unexpected bonus :
new exotic quarkonium(-like) states
this lecture – experiment
Mikhail Voloshyn – theory
2
X(3872)
CP
B→Xsγ
630
365
Belle citation count
548
Phys.Rev.Lett.91 262001, (2003)
9th anniversary!
Outline
Conventional quarkonium
X(3872)
1– – family
_
Charged states with bb pairs
Heavy quarkonium
Approximately non-relativistic
System
_ _
uu,dd
_
ss
_
cc
_
bb
Ground triplet state
(v/c)2
Name
Mass, MeV
, MeV
r
800
150
~1.0
f
1000
4
~0.8
y
3100
0.09
~0.25

9500
0.05
~0.08
“hydrogen atom” of QCD
Rich array of bound states
Charmonium Levels
M, GeV
4.50
S = s1 + s2 = {0, 1}
J=S+L
n – radial quantum number
y(4415)
4.25
y(4160)
c2(2P)
4.00
y(3770)
c(2S)
2M(D)
y(2S)
hc
3.50
c2
c1
c0
L=0 S=0
0– +
c (1S), c(2S)
L=0 S=1
1– –
J/y , y(2S) ,
y(4040) , y(4415)
L=1 S=0
1+ –
hc(1P)
L=1 S=1
0+ +
1+ +
2+ +
c0(1P)
c1(1P)
c2(1P), c2 (2P)
L=2 S=1
1– –
y(3770), y(4160)
3.25
J/y
3.00
2.75
c
0– +
1– –
C = (–1)L+S
JPC
y(4040)
3.75
P = (–1)L+1
1+ –
(0,1,2)++
JPC
n2S+1LJ y(3770) = 13D1 + 0.2  23S1
6
Bottomonium levels
notation :
•y
• subscript “c”  ”b”


7
Observation of J/y
BNL AGS
SLAC SPEAR e+e- annihilation
Mark I first 4 detector
extracted 28 GeV p-beam
Be target
, nb
, nb
e  e   hadrons
p + Be → e+e- + X
Richter et al.
e e     
, nb
Ting et al.
Width of t
M(
e+e-
)
JPC=1– –
ee  ee
E c.m.s.
8
Observation of J/y
Nov 1974 – revolution
J/y is heavy and very narrow  smth new
 Observation of 4th quark
 Quarks were widely recognized as particles
 Beginning of modern physics
9
Why J/y is so narrow?
, MeV
0.093 ± 0.002
0.327 ± 0.011
27 ± 4
11 ± 1
27 ± 1
85 ± 12
J/y
y(2S)
c
c0
y(3770)
y(4040)
C-parity
1/3 2/3
c
~as3
‾
c
c
‾
c
g
c
g
‾
c
g
e,,q
DD*
D*D*
DD
at
threshold
e,,q
¯
For J/y strong decays are suppressed so much
that EM decays are competitive.
10
Observation of y family
JPC of photon  produced in e+e- collisions
1– –
R = (e+e-  hadrons) / 0(e+e-  +-)
0 = 4a2 / 3s
11
Observation of cJ and c
y(2S)  cJ g
cJ  J/y g
y(2S)  c g
0– + 1– –
E1
E1
M1
(0,1,2)+ +
12
Observation of
cJ
c
– DASP, DESY (1976)
– Crystall Ball, SLAC (1980)
Crystal Ball: sphere
with 900 NaI crystals
13
Charmonium before B-factories
1980 – 2002 : no new charmonium states
14
Bottomonium before B-factories
1– –
(0,1,2)+ +
Lederman
(1S), (2S) – 1977 FNAL
pA collisions
e+e- colliders:
DORIS, DORIS-II (DESY)
CESR (Cornell)
VEPP-4 (Novosibirsk)
1985 – 2008 : no new
bottomonium states
15
B-factories
Data taking : 2000 – 2010
e+e– → (4S)
Ecms ~ 10.6 GeV
@ KEK
@ SLAC
16
Charmonium production at B factories
in B decays
γγ fusion
c(2S)
c2(2P)
Any quantum numbers can be produced,
to be determined from angular analysis.
double charmonium production
initial state radiation
JPC =
JPC = 0± +, 2± +
1– –
Only JPC = 0± + observed so far.
17
Observation of hc(1P)
CLEOc 2005 (c-Factory)
y(2S)  hc(1P) 0
0
1– –
1+ –
18
QCD potential
Schrödinger equation
V (r )  
a s (r )
one-gluon exchange,
asymptotic freedom
r
 r
confining potential,
“chromoelectric tube”
There are other
parameterizations,
shapes are similar
for 0.1 < R < 1 fm.
c J/y c2 y(2S)
19
Predictions of
Potential Models
State
Experim
20
M, GeV
Predictions of Potential Models
Potential models reproduce also
annihilation widths
J/y, y(2S)→ℓ+ℓc, cJ → gg and
radiative transitions btw. charmonia.
JPC
21
X(3872)
22
PRL91,262001 (2003)
X(3872) was observed by Belle in
B+ → K+ X(3872)
→ J/ψ π+ π-
y(2S)
X(3872)
Confirmed by CDF, D0 and BaBar (+LHCb)
Recent signals of X(3872) → J/ψ π+ πpp collisions
PRL103,152001(2009)
arXiv:0809.1224
direct production
only 16% from B
PRL93,162002(2004)
PRD 77,111101 (2008)
23
Puzzles of X(3872)
_
2003 revolution
Mass above DD threshold, but very narrow
M = 3871.63  0.19 MeV , Γ < 1.2 MeV (90% C.L.)
X(3872) → J/ψ π+ π-
M(+-)
 +- pair is produced via r0
X(3872) is observed in isospin-violating mode
Bf(XJ/y ) / Bf(XJ/y r) = 0.8  0.3
confirm even C-parity
Bf(XJ/y g) / Bf(XJ/y r) = 0.21
_  0.06
expect for cc ~20
Mass close to D*0D0 threshold: m = – 0.09  0.34 MeV
Very unlikely that X(3872) is charmonium
24
Exotic interpretations
u
c
tetraquark
c u
compact diquarkdiantiquark state
Tetraquark 
Predictions:
π c
c
u
u
molecule
two loosely bound
D mesons
Maiani, Polosa, Riquer, Piccini;
Ebert, Faustov, Galkin; …
1. Charged partners of X(3872).
2. Two neutral states ∆M = 8  3 MeV,
one populate B+ decay, the other B0.
Experiment:
BaBar, Belle : J/y+0 channel  no charged partner
CDF : signal shape in J/y+- channel
Belle : production in B+ and B0 decays
no 2nd neutral resonances
Tetraquarks are not supported by any experimental evidence.
25
Molecule
Swanson, Close, Page; Voloshin; Kalashnikova, Nefediev; Braaten; Simonov, Danilkin ...
Mass close to D*0D0 threshold: m = – 0.09  0.34 MeV
_
a few fm
Weakly bound S-wave D*0D0 system
JP = 1 +
Large isospin violation  8 MeV difference btw D*+D- and D*0D0 thresholds.
_
Large production rate in pp and in B decays  admixture of c1(2P).
_
Predicts different line shapes for J/y+- and D*0D0 modes:
Bound state
J/y+-
Virtual state
D0D00
D0D00
D*0D0
J/y+-
26
X(3872) → D*0D0
B K
arXiv:0810.0358
D0D*0
D*→Dγ
PRD77,011102(2008)
4.9σ
B+& B0 D0D*0K
D*→D0π0
605 fb-1
347fb-1
Flatte vs BW similar result: 8.8σ
~2
Bf(XDD*) / Bf(XJ/yr)
= 9.5  3.1
Shifted mass and higher
width are in accord with
molecular model
27
Molecule (2)
Bound or virtual?

c1(2P) admixture?
Simultaneous analysis of
J/y and DD* data
Braaten, Stapleton
Zhang, Meng, Zheng
arXiv: 0907.3167
0901.1553
Kalashnikova, Nefediev arXiv:0907.4901
State
c1(2P)
admixture
Belle data
bound
~ 30%
BaBar data
virtual
~0
~2 experimental difference reverses conclusion
 Present statistics are insufficient to constrain theory
28
Angular analysis
CDF, BELLE  all JPC except 1++ and 2-+ are excluded
MC
JPC= 2-+
MC
JPC=1++
cosqX
cosqX
cos
cos
cosql
cosql
cosqr
cosqr
29
Nature of binding force
One pion exchange ?
Coupled channel resonance ?
D
c1
D
c1
D*
c1
D*
30
“Loose ends”
_
Improve line-shape measurement for D*0D0
Super B-factories
Angular analysis to discriminate JPC=1++ and 2 – +
LHCb
More decay channels : 00y, +-c
BELLE ?, LHCb, Super B-factories
31
–
–
1
family
32
Use ISR to measure
open&hidden charm exclusive final states
eγ+
e–
e–
cc
e+
s =(Ecm– Eγ)2 – p2
ISR at B factories
Quantum numbers of final states are fixed JPC
= 1– –
Continuous ISR spectrum:
• access to the whole √s interval
• αem suppression compensated by huge luminosity
• comparable sensitivity to energy scan (CLEO-c, BES)
33
e+e– → gISR J/y (y) +- : Y(4008,4260,4360,4660)
PRL99, 182004
550/fb
arXiv: 0808.1543
454/fb
PRL99, 142002
670/fb
PRL98, 212001
298/fb
–
Above DD threshold, decay to open charm?
34
Y(4660)
ψ
y (4415)
Y(4260)
Y(4325)
Y(4360)
y (4160)
ψ(4160)
ψ
y (4040)
Y(4008)
ψ
y (3770)
(e+e–→hadrons)
R(s) =
– Ruds
(e+e–→μ+μ–)
No evidence for Y’s → hadrons
Durham Data Base
 ee is small. Since eeB(Yy) is finite (is measured)  B(Yy) is big
X.H. Mo et al, PL B640, 182 (2006)
 (Y(4260) → J/y+-) > 0.508 MeV @ 90% CL
Much larger than measured
charmonium widths:
(y→ J/y+-) = 0.044 ± 0.008 MeV
(y → J/y+-) = 0.104 ± 0.004 MeV
35
Interpretation
PRD80, 091101R (2010)
c
c
hybrid
g state with excited qluonic
degree of freedom
Y(4260) ψ(4415)
DD*
–
–
hybrid → D**
D
→
(D*π)
D
1
c c–
π
π
hadrocharmonium
charmonium embedded
into light hadron
predictions?
36
DD
DD*
D*D*
DDπ
DD*π
Λ+c Λ–c
D(*)+s D(*)–s
Inclusive cross-section
is saturated by
exclusive contributions
37
Charged resonances
_
with bb
(5S) 
Zb(10610)+ 
+
Zb(10650) 
arXiv:1103.3419
(1S)+ (2S)+ (3S)+ hb(1P)+ hb(2P)+ -
arXiv:1110.2251
38
Integrated Luminosity at B-factories
(fb-1)
asymmetric e+e- collisions
> 1 ab-1
On resonance:
(5S): 121 fb-1
(4S): 711 fb-1
(3S): 3 fb-1
(2S): 24 fb-1
(1S): 6 fb-1
Off reson./scan :
~100 fb-1
530 fb-1
On resonance:
(4S): 433 fb-1
(3S): 30 fb-1
(2S): 14 fb-1
Off reson./scan :
~54 fb-1
39
e+e- hadronic cross-section
BaBar PRL 102, 012001 (2009)
(1S)
(5S)
(6S)
(4S)
(2S)
(3S)
(4S)
Belle took data at
E=10867 1 MэВ
2M(B)
2M(Bs)
_
e+ e- ->(4S) -> BB, where B is B+ or B0
_
_
_
_
_
e+ e- -> bb ((5S)) -> B(*)B(*), B(*)B(*), BB, Bs(*)Bs(*), (1S)  ,  X …
study
40
Puzzles of (5S) decays
Anomalous production of (nS) +PRL100,112001(2008)
(MeV)
PRD82,091106R(2010)
line shape
of Yb
102
(5S)
Similar effect in charmonium?
Y(4260) with anomalous (J/y +-)
 assume  Yb close to (5S)
to distinguish  energy scan
 shapes of Rb and () different (2)
41
Observation of
hb(1P) & hb(2P)
42
Trigger
CLEO observed e+e- → hc +– @ ECM=4170MeV
(hc +–)  (J/y +–)
PRL107, 041803 (2011)
Y(4260)
Hint of rise in (hc+-)
@ Y(4260) ?
4260
Y(4260)Yb  search for hb(nP)+- @ (5S)
43
Introduction to hb(nP)
_
(bb) : S=0 L=1 JPC=1+
Expected mass
 (Mb0 + 3 Mb1 + 5 Mb2) / 9
MHF  test of hyperfine interaction
For hc MHF = 0.00  0.15 MeV,
expect smaller deviation for hb(nP)
Previous search
arXiv:1102.4565
PRD 84, 091101
BaBar
3.0
(3S) → 0 hb(1P)
MM(+-)
44
Introduction to hb(nP)
_
(bb) : S=0 L=1 JPC=1+
Expected mass
 (Mb0 + 3 Mb1 + 5 Mb2) / 9
MHF  test of hyperfine interaction
For hc MHF = 0.00  0.15 MeV,
expect smaller deviation for hb(nP)
Previous search
arXiv:1102.4565
PRD 84, 091101
BaBar
3.0
(3S) → 0 hb(1P)
MM(+-)
45
(5S)  hb +- reconstruction
hb → ggg, gb (→ gg)  no good exclusive final states
reconstructed
“Missing mass”
M(hb) = (Ec.m. – E*+-)2 – p+* 2  Mmiss(+-)
(1S)
hb(1P) (2S) hb(2P) (3S)
46
Results
121.4 fb-1
Significance w/
systematics
hb(1P) 5.5
hb(2P) 11.2
47
Hyperfine splitting
Deviations from CoG (Center of Gravity) of bJ masses
hb(1P) (1.7  1.5) MeV/c2 consistent with zero, as expected
2
hb(2P) (0.5 +1.6
-1.2 ) MeV/c
Ratio of production rates
spin-flip
=
for hb(1P)
for hb(2P)
no spin-flip
Process with spin-flip of heavy quark is not suppressed
 Mechanism of (5S)  hb(nP) +- decay violates
Heavy Quark Spin Symmetry
48
Resonant structure of
(5S)hb(nP)
+
 
49
M(hb–), GeV/c2
Resonant structure of (5S)  hb(1P) +phase-space MC
M(hb+), GeV/c2
50
phase-space MC
fit Mmiss(+–)
in M(hb) bins 
hb(1P) yield / 10MeV
M(hb–), GeV/c2
Resonant structure of (5S)  hb(1P) +121.4 fb-1
M(hb+), GeV/c2
 Zb(10610), Zb(10650)
M(hb), GeV/c2
Fit function
_
Results
MeV/c2 ~BB* threshold
M1 =
1 =
MeV
a=
_
18 (16 w/ syst)
MeV/c2 ~B*B* threshold
M2 =
2 =
Significance
MeV
non-res.~0
=
degrees
51
phase-space MC
fit Mmiss(+–)
in M(hb) bins 
hb(1P) yield / 10MeV
M(hb–), GeV/c2
Resonant structure of (5S)  hb(2P) +121.4 fb-1
M(hb+), GeV/c2
hb(1P)+M1 =
1 =
M2 =
2 =
hb(2P)+MeV/c2
MeV/c2
MeV
MeV
MeV/c2
MeV/c2
MeV
MeV
Significances
6.7 (5.6 w/ syst)
a=
=
M(hb), GeV/c2
degrees
non-res.~0
degrees
non-res. set to zero
52
Resonant structure of
(5S)(nS)
+
 
(n=1,2,3)
53
(5S)  (nS) + +-
(n = 1,2,3)
(3S)
(2S)
(1S)
reflections
Mmiss (+-), GeV/c2
54
(5S)  (nS) + +-
(n = 1,2,3)
purity 92 – 94%
(3S)
(2S)
(1S)
Mmiss (+-), GeV/c2
55
(5S) (nS) +- Dalitz plots
(1S)
(2S)
(3S)
56
(5S) (nS) +- Dalitz plots
(1S)
(2S)
(3S)
 Signals of Zb(10610) and Zb(10650)
57
Results of Dalitz plots analyses
(2S)
(1S)
(3S)
58
Results of Dalitz plots analyses
(1S)
(3S)
(2S)
59
Summary of Zb parameters
Average over 5 channels
 M1  = 10607.22.0 MeV
 1  = 18.42.4 MeV
 M2  = 10652.21.5 MeV
 2  = 11.5  2.2 MeV
Angular analysis  JP = 1+ for both Zb
60
Summary of Zb parameters
Average over 5 channels
 M1  = 10607.22.0 MeV
 1  = 18.42.4 MeV
o
 = 180
 M2  = 10652.21.5
MeV
 = 0o
hb(1P) yield / 10MeV
 2  = 11.5  2.2 MeV
M(hb), GeV/c2
Zb(10610) yield ~ Zb(10650) yield in every channel
Relative phases: 0o for  and 180o for hb
61
Heavy quark structure in Zb
Bondar et al. PRD84 054010 (arXiv:1105.4473)
Wave func. at large distance – B(*)B*
1   1 
'
Z


 1
Qq
b
0
Qq
bb 0
bb1
2
2
1   1 
Z


 1
Qq
b
0
Qq
bb 0
bb1
2
2
Explains
• Why hb is unsuppressed relative to 
• Relative phase ~0 for  and ~1800 for hb
• Production rates of Zb(10610) and Zb(10650) are similar
• Widths
–”–
Predicts
• Existence of other similar states
Other Possible Explanations
• Coupled channel resonances (I.V.Danilkin et al, arXiv:1106.1552)
• Cusp
(D.Bugg Europhys.Lett.96 (2011),arXiv:1105.5492)
• Tetraquark
(M.Karliner, H.Lipkin, arXiv:0802.0649)
62
_
States that do not fit qq table
QWG, arXiv:1010.5827
63
States that do not fit qq table
BZK
QWG, arXiv:1010.5827
multiquark candidates
Z(4430)+
widths 100–200 MeV
 difficult to interpret
rescattering?
Pakhlov PLB702,139(2011)
64
Conclusions
Quark Model provides good description of quarkonium
below open flavor threshold
Above threshold  new regime : light quarks become important
 molecules, hadrocharmonium (... ?)
 observations at B-factories
BELLE established new type of elementary particles
We knew that neucleons can form bound states (deutron, nuclei)
Now we know that D and B mesons can form bound states
“Meson chemistry”
65