1. The Impact of BaBar ISR data on the SM Muon Anomaly Prediction
The Impact of BaBar ISR data on
the SM Muon Anomaly Prediction
Michel Davier
Laboratoire de l’Accélérateur Linéaire, Orsay
Muon Magnetic Moment Workshop
October , 2007, University of Glasgow   
hadrons

2. Goals of the BaBar ISR Program
Precise measurements of cross section for all significant processes, e+e hadrons, from threshold to ~4-5GeV
Measure , KK channels with high precision
Summing up exclusive cross sections ==>Improve the precision of R
Study spectroscopy of JPC=1−− states and their decays
M. Davier et al., 2003 Ös

3. Exclusive Channels with BaBar ISR
systematic program underway using ISR from (4S) energies, taking
advantage of high luminosity (B-factory)
statistics comparable to CMD-2/SND for Ecm<1.4 GeV, much better than
DM1/DM2 above
full energy range covered at the same time
channels identified using particle ID and kinematic fitting
systematic uncertainties at 5-10% level
large acceptance for hadronic system (boosted opposite to ISR photon)
X = 2E /Ecm
ISR
H is radiation function

4. BaBar ISR: e+ehadrons
Reactions for which results have been published :
pp PRD 73, (2006)
p+p-p PRD 70, (2004)
2p+2p-, K+K- p+p-, PRD 71, (2005)
K+K- p+p- K+K- p0p0 , 2K+2K PRD 76, (2007)
3p+3p-, 2p+2p-p0p0, K+K-2p+2p PRD 73, (2006)
New results presented last Summer :
K+Kp0, KSKp+, K+Kh, subm. to PRD arXiv:0710.xxxx [hep-ex]
LL , LS0 , S0S subm. to PRD arXiv:  [hep-ex]
+pp BaBar Preliminary
2p+2pp0,2p+2ph, KK p+pp0, KKp+ph
accept. by PRDarXiv:  [hep-ex]
Work in progress:
, K+K, p+p3p0
Inclusive R

5. BaBar ISR:  errors include systematics huge discrepancy with DM2
SND
BaBar
DM2
contribution to ahad ( GeV) :
all before BaBar  0.26  0.03
all + BaBar  0.19  0.01
all – DM2 + BaBar  0.09  0.01
x1010

6. BaBar ISR: 22 contribution to ahad (<1.8 GeV) :
all before BaBar  0.87  0.24
all + BaBar  0.44  0.00
x1010

7. BaBar ISR: 33 BaBar contribution to ahad (<1.8 GeV) :
all before BaBar  0.10
all + BaBar  0.016
x1010

8. BaBar ISR: 222 BaBar contribution to ahad (<1.8 GeV) :
all before BaBar  0.30  0.03
all + BaBar  0.093
x1010

9. Only statistical errors plotted
BaBar ISR: +00
Only statistical errors plotted
BaBar
preliminary
ψ ->p0p0J/ψ(->mm)
J/ψ
Previous situation chaotic
Preliminary syst. error: 8% in peak 5%
Good agreement with SND <1.4 GeV
Huge improvement >1.4 GeV
First measurement >2.5 GeV

10. BaBar ISR: +00  --substructure
Intermediate states:
0
+- large and first seen
0 f0(980)
a1(1260)
BaBar
preliminary MC

11. BaBar ISR: ++0 Cross sections of sub-mode: +-  0 
X =  3 + 0 3 : from subtraction /+-

0
3

12. BaBar ISR: +p- BaBar,3 1.35  0.03 0.45  0.14 1.66  0.01
preliminary
BaBar,3
 
BaBar
preliminary
f0(980)
1st measurement
1.35  0.03
0.45  0.14
1.66  0.01
0.22  0.04
BaBar,3

13. BaBar ISR: p+-+p- ~4,300 events selected first measurement BaBar
preliminary

14. BaBar ISR: KSK , K+K-p
Dominant states:
K*(980)K and
K2*(1430)K
K+K-p
Isoscalar channel dominates
over isovector
Parameters (1680): PDG
m=172320 MeV, 20
 = 37175 MeV, 50
ee= 58060 eV,
B/BK*K 1/3

15. BaBar ISR: KK , K+K-pp
Substructure in the final state
K*(892) - 1 per event
K+K-0 p0
K+K-0 p0
K1(1270),K1(1400) – 1+
K+K-p+ p-
~ 1500

16. BaBar ISR:KKKK,KKppp,KKpp
jK+K- dominated
J/Y
K+K-+p-p
K+K-+p-
First measurement !

17. BaBar ISR: KKpppp
Cross section
Substructures
K*0(892) j
J/y
first measurement

18. Present BaBar Measurements
only statistical errors
syst. 5-10%
to obtain R in the energy range 1-2 GeV the processes
+-, +-30, +-40, K+K-, KSKL, KSKL, KSK+ -0
remain to be measured

19. Conclusions program underway with BaBar to measure all significant
exclusive cross sections for ee  hadrons using ISR
many channels already published; more underway
should allow reconstruction of R from threshold to 2 GeV
will match inclusive data from BES from 2 to 5 GeV
important input for VP calculations and QCD analyses
BaBar will be the only experiment able to provide the whole
input in the low-energy region, with good accuracy