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Results on Charmonium and Bottomonium. Tom Browder (University of Hawaii). Will cover results from BESII, CLEO(-c), BaBar and Belle. Apologies: Not an expert but a backup speaker. Can only cover a small subset of interesting results in the available time. - PowerPoint PPT Presentation
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Results on Charmonium and Bottomonium Tom Browder (University of Hawaii)
Will cover results from BESII, CLEO(-c), BaBar and Belle
Thanks: I have borrowed from talks by Pedlar, Shepard, Olsen, Muramatsu, Mussa, CZ Yuan, Skwarnicki. I have benefitted from correspondence with Soren Prell and others.
Apologies: Not an expert but a backup speaker. Can only cover a small subset of interesting results in the available time.
Charmonium
r
mesons formed from c- and c-quarks
c-quarks are heavy: mc ~ 1.5 GeV 2mp
velocities small: v/c~1/4 (for b b, v/c ~0.1)
non-relativistic QM applies
c c
_
ErVmr
)(2
22
What is V(r) ??
S. Olsen
“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
Charmonium spectrum
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
(4
040)
(4
160)
(4
415)
Important BES contribution to R
(3770), (4040), (4160), (4415)In 1998 and 1999, BES scanned 91 energy pointsbetween 2 and 5 GeV to determine R.
Phys. Rev. Lett. 84, 594 (2000) and 88, 101802, (2002).
Results from the new R analysis (2007)
hep-ex: 0705.4500
Resonance parameters (PLB660, 315 (2008))
BESII : J/ 2001 – 58 M; CLEO-c: (2S) 2006 -27 M
0
10
20
30
40
50
60
MarkIII DM2 BESI BESII
CLEO-c has CsI(Tl) crystals, BESII does not but BESIII will .
Current J/ and (2S) Samples (×106)Note: B( ψ(2S)->+-J/ψ)~32% one can tag J/ψ events very cleanly and efficiently.
Inclusive photon signal for ψ’γ ηc
B(ψ(2S)->γ ηc (1S)) = (4.32+-0.16+-0.60)*10^-3B(J/ ψ->γ ηc (1S)) = (1.98+-0.09+-0.30)%
B(J/ ψ->γ ηc (1S))/B( ψ(2S)->γ ηc (1S)) = 4.59+-0.23+-0.64.
arXiv:0805.0252
Renormalize ηc
BF scale
Signal for J/ψγηc
Discrepancy between ηc properties (especially
widths) in different processes is unresolved.
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 keVallowed
(’J/) 0.3 keVisospin violating
“reasonable” agreement between
measurement & th
eory
c.f. Kuang & Yan PRD 41 155
ψ0 hc0γ ηc
CLEO 2005 +2007 update Belle 2002
Charmonium table below D Dbar threshold is complete
The hcand ηc(2S) have been observed
Recent results on non-exotic charmonia
13D1 13P1 11P0
seen by CLEO, Phys.Rev.D74:031106,2006.
(meas) = 75 18 keV(theor) ~59-77 keV
11P1 (hc) found by CLEOhep-ex/0508037properties as expected
23P2 found by Bellehep-ex/0507033properties as expected
21S0 (ηc(2S)) found by BelleS.K.Choi et al PRL 89 102001
properties as expected
The old “missing states” (hc and ηc(2S)) have now been observed
May 1, 2003
The potential model for (ccbar) charmonium mesons is robust and reliable.
Declare victory
K*K
ρπ
MARK-II
Old unsolved mystery
Problems with strong decays of charmonium
X-H Mo et al, review in hep-ph/06011214 (>10 proposals)
RosnerOne possible explanation
W. S Hou’s idea, glueball-J/ψ mixing, seems to be ruled out
’ Baryon Anti-baryon OK First measurements by BESI, remeasure BR with BESII
data sample.
pp-bar
ΛΛ-bar
ΣΣ-bar
’ pp
’ ΛΛ pπ-pπ+
’ Σ0 Σ0
pπ-pπ+ ΞΞ-bar’ Ξ- Ξ+
p2π-p2π+
Consistent with “12% rule”.
Bottomonium Data Samples
~14.4fb-1 on the Y(2S)Belle 2.9 fb-1 (2006) , 11 M Y(3S) BaBar, 30.3 fb-1, ~120 M Y(3S)
Bottomonium: Some mysteries in strong decays
“QCD Multipole Expansion”
( )mS ( )nS
What is special about the case m-n > 1 ?
'
Most famous ancient mystery (1994-2000)
Possible Theoretical Explanations:
High statistics data and sophisticated analysis may provide some clues (CLEO)
The matrix element for Υ(mS)Υ(nS)
In the above, ε, ε’ are the polarization vectors of the Υ(nS), Υ(mS)
q1, q2 are the pion 4-vectors while E1, E2 are their energies in the Υ rest frames. q2 is the invariant mass of the two pions
The amplitudes A, B could be complex
CLEO High Statistics Analysis of di-pion matrix element
M, θX
CLEO High Statistics Analysis of di-pion matrix element
A, B are complex. B was previously neglected
C is consistent with zero (spin flip and breakdown of QCD multipole expansion not present). PRD 76, 072001
(2006)
Belle dataBaBar data
PRD 071103 (R) 2007
Recent data for Υ(4S)Υ(1S,2S) + - Non-B Bbar decay
PRL 96 (2006) 232001
CLEO’s first evidence for (2S)(1S) η
4( (2 ) (1 ) ) (2.31 0.74) 10BF S S
0 4( (2 ) (1 ) ) 1.6 10BF S S One candidate is found,
4.6σ
Expect this is 16% of the η mode
preliminary
BaBar discovers Υ(4S)(1S)η
These are examples of non-B Bbar decays that have been observed by BaBar and Belle.
3( (2 ) (1 ) )(1.3 0.5) 10
( (2 ) (1 ) )
S S
S S
preliminary
Could related transitions provide a way to discover the elusive hb or ηb ?
(3 ) (2 ) ( )b bS P (Voloshin, Mod. Phys. Lett. A 19, 2895 (2004))
0(3 ) ,b b bS h h (Godfrey, Rosner, PRD66, 014012 (2002) like CLEO’s hc search )
Two suggestions:
Where is the ground state bottomonium ηb ?
Which Upsilon(nS) is best ? Inclusive or exclusive ? What are the
hadronic modes of the ηb ?
Tests theory and is the highest priority of the quarkonium working group (QWG)
Direct M1 transitions
Second mystery or big problem in the field:
Where is the ηb, the ground state bottomonium state ?
Total cross-section
Search for a Y(4260) analogue in the bottomonium sector
Y(4260) → J/ + - Is there a corresponding bb state b → (1S) + - ?
Resonant structure is rather complicated above BB threshold.
E.g. Y(10860) is commonly assumed to be a radially excited 1-- b b bound state a.k.a the Y(5S), but we do not really know that.
World wide Y(10860) data:
1985 CLEO 0.1/fb
2003 CLEO III 0.43/fb
2005 Belle 1.9/fb
2006 Belle 21.7/fb
“Searching for the bottom counterparts of X(3872) and Y(4260) via + -Υ(1S)”,
Wei-Shu Hou, PR D74, 017504 (2006) → theory inspiration
(experimental work by Kai-Feng Chen and Anatoly Sokolov)
Collected mainly for Bs physics, ≈105 Bs / fb
Use this data to measure + - Υ(1,2,3S) production at the (10860)
Anomalous (1,2,3S) +-, (1S) +- cross sections at (5S)
(10860) decay or decay of new overlapping state Yb? Energy scan (7.9 / fb) around (10860) : compare S)
and total hadronic cross sections. Results will be ready soon.
(10860)
(2S)
(1S)
Final state
Initial state
(3S)
(2S)
(3S)
(1S)
(10860)
tot MeV (1S)+- keV
(2S) 0.032 6
(3S) 0.020 0.9
(4S) 20.5 1.8
(10860) 110 590
PRL 100, 112001, 21.7 fb-
1
Phase space, Cahn-Brown model (B=0)
What about the dipion mass distributions for the Y(10860) ? (the state formerly known as the “Υ(5S)”)
There are hints of a low mass structure in a) and b) but statistics are low.
Bottomonium: New Physics Potential
Suppose those precision electroweak fits are taken literally, MH~76±30 GeV.
Suppose nMSSM is correct, then there is a H and another light Higgs particle a1 (m(a1) <m(b)). Can avoid LEP limits and still have MH~100 GeV. (R. Dermisek, J. Gunion, B. McElrath)
The dominant decay mode might be:
1 1 ( )( )H a a
Difficult at a hadron collider. But could find the light Higgs (a1) in bottomonium at B or Super B Factories.
Bottomonium: New Physics Potential (cont’d)
One motivation for BaBar’s 30 fb-1 Y(3S) run.
Hunting dark matter or light Higgs in Υ(nS) decaysHigh precision check of lepton universality in dilepton decays Light Higgs signature
Can also search for the HYPER-CP particle using decays to aμ+ μ-
Expect compelling results on bottomonium from BaBar (and perhaps Belle) in the near future.
BaBar’s final runKirkby
More New Results (but not enough time to cover)
New Measurements of Upsilon(3S) Branching Fractions (CLEO)
New Measurements of Upsilon(3S) Branching Fractions (CLEO)
It looks like there may be a bbversion of the Y(4260)
lurking around the (5S)
If there are bb versions of the XYZ’s, why not ss versions as well?
W.-S. Hou PRD 74, 017504 (2007)
1-- Ys states around 2 GeV?Y(2175)f0(980)
from BaBar (confirmed by BESII)
e+e- f0(980)@ Ecm ~10.6 GeV
confirmed by BESII
M(f0(980) GeV
M.Ablikim et al (BES)PRL 100, 102003
(2008)
Backup Slides
The new 2007 improved results
Comparison of the updated R value and the old results in Phys. Rev. Lett. 88 (2002) 101802
Differences in R values are due to the updated resonant parameters and initial state radiative correction factor (1+obs).
preliminary
hep-ex: 0705.4500
0
0.5
1
1.5
2
2.5
3
3.5
4
BES
CLEO
’ Baryon antibaryon OK
BESII – CLEOccomparison
pp-bar ΛΛ-bar ΣΣ-bar ΞΞ-bar
Consistent with SU(3) symmetry.
Reduced Branching Ratios
R = Br/(π p* /s½), p* is baryonmomentum.
R’s same under SU(3) symmetry.
BES
Phys. Lett. B648, 149 (2007)
Belle:((5S)(nS))
2S
3S4S
(4S) (1S) +
(4S)(1S)477 fb-1 from Belle
44±
8 e
vts
“(5S)”(1S)23.6 fb-1 from Belle
(1/20 times the data &
~1/10th the crosssection)
325±
20
evts
!
8 times as many events!
Belle 0710.2577
K.F. Chen et al (Belle) PRL 100, 112001 (2008)
(2 weeks ago)
is Huge!!
Partial Widths
N.B. Resonance cross section 0.302 ± 0.015 nb at 10.87 GeV PRD 98, 052001 (2007) [Belle]
Cf (2S) (1S) ~ 6 keV (3S) 0.9 keV (4S) 1.8 keV
Assume “(5S)” = (5S)PDG value taken for (nS) properties
>100 times bigger!!
Where is the ground state bottomonium ηb ?
Which Upsilon(nS) is best ? Inclusive or exclusive ? What are the
hadronic modes of the ηb ?
Tests theory and is the highest priority of the quarkonium working group (QWG)