1. Some Low Energy e+e- Open Questions for a future SuperB Factory
R. Baldini Ferroli, Centro Fermi/INFN-LNF
SuperB Factory 2nd workshop, Frascati 2006
SuperB 06

2. Possible (pessimistic) scenario
BES III : no data collected below J/y
VEPP2000: no data above 1.9 GeV
DANAE : not funded
Possible (optimistic) scenario
VEPP2000: up to 2.0 GeV
DANAE : up to 2.4 GeV
SuperB 06

3. Summary stot(e+e- hadrons, Q< 3 GeV) , gg  pp Mpp< 1 GeV
Hadronic Chemistry:
light quark “exotic” (no qq) excitations
Golden channels : f f0(980), f p0, ...
Nucleon time-like Form Factors:
Proton: GE/GM , fE- fM
Neutron, Hyperons
SuperB 06

4. Measurement of R(s) : work (always) in progress
CMD-2/KLOE s < 1 GeV
at ~ 1% level
ADONE 1< s < 2 GeV at ~10% level
BES < s < 5 GeV at ~ 6% level
BaBar/BESIII will improve it
SuperB 06

5. Hadronic Chemistry Charm quark sector:
Very likely at least one molecule: X(3870)
No qq states:DsJ(2317), Y(4260),….
What about light and strange quark sector:
Forbidden ?
More difficult to be detected ?
SuperB 06

6. Clear evidence that f0(980) is a 4q state
Some evidence for at least one resonance in e+e-  f f0(980) at ~ 2.1 GeV
Glueballs, Hibrids, 4q mostly isoscalar
Golden channels for exotic also isovector:
f p0, 6 p ....
All these channels low cross sections 
Luminosity requirement ~ 100 ISR BaBar
~ 0.5 x 1032 cm-2s-1
SuperB 06

7. 2 mH = nqq hel.suppres.
SuperB 06

8. s[ e+e- f f0(980) ]
SuperB 06

9. Diffractive photoproduction of 6p by E687:
SuperB 06

10. SuperB 06

11. Golden isovector channel: e+e- f p0
SuperB 06

12. Nucleon Form Factors We were supposed to know the nucleon:
Scaling law on GpE/GpM, but:
space-like JLAB on GpE/GpM
Smooth time-like above threshold, but:
steps down sharply at ~ 2.2 and 2.9 GeV
No Baryonium, but:
sharp FF drop just above threshold
SuperB 06

13. Renewed interest in nucleon FF
by space-like GE/GM JLab measurement of recoil polarization
Rosenbluth
Polarization
Crossing zero at |Q2| ~ 10 GeV2 ?
SuperB 06

14. F.Iachello, A.D.Jackson, A.Lande (1973)
SuperB 06

15. Time-like |GpE/GpM|
SuperB 06

16. “Dressed” cross section
Step at w ~ 2.2 GeV (!?)
Speculations:
Strong resonances interference ?
A new (inelastic) amplitude:
opening of baryonic excitations?
SuperB 06

17. More difficult to interpretate !
Step at w ~ 2.9 GeV (!?)
More difficult to interpretate !
SuperB 06

18. Very near threshold Form Factor
Steep behaviour at threshold confirmed
Steep behaviour at threshold also seen in other processes
SuperB 06

19. Steep behaviour at threshold also seen in other processes,
with different quantum numbers
BES
BaBar
Corrected for
phase space
SuperB 06

20. Present Neutron Time-like Data
One measurement only: FENICE at ADONE
~ 100 events at 1.9 < Q < 2.55 GeV
Rn = s(e+e-  n n) / s(e+e-  p p) > 1
Hints for GE<< GM (sharp thresh. behavior ?)
SuperB 06

21. Cross sections: nn versus pp
SuperB 06

22. Neutron magnetic time-like FF
SuperB 06

23. Short range perspectives
ISR in BaBar, Belle, BESIII:
Not enough integrated luminosity
Not enough en to detect nn events
VEPP2000:
Limited energy range
Nucleon detection difficult at threshold
SuperB 06

24. Conclusions and perspectives
If DANAE will be approved 
some items will be covered
If SuperB ~ 100 PEPII and good en _
ISR should allow all these measurements
Colliding a low energy linac with e+ beam
(PEPN scheme)
even better, with a dedicated detector
SuperB 06

25. SuperB 06

26. e+e- f h
SuperB 06

27. Early successfull predictions
T.Massam, A.Zichichi, NC 43(’66)1137:
(J.Ellis, M.Karliner NewJP 4(’02)4)
VDM + SU extended source R ~ 1/MN
+ first time-like experimental constraint
FiN ~ 1/(1-Q2/MN2) SV gV fV /(1- Q2/mv2) ~ Skyrme model
F.Iachello, A.D.Jackson,A.Lande, PL 43B(’73)191,
(M.Gari, W.Krumpelmann, PL 173B(’86)10)
VDM + extended source R ~ 1/MN + Hard core (~pQCD)
Both models predict s(e+e-n n) ³ s(e+e-p p)
SuperB 06

28. I.S.R. Main Features
SuperB 06

29. I.S.R. versus c.m. Advantages:
All energies at the same time  less systematics
c.m. boost  e ≠ sw~ 1 MeV at threshold
Drawbacks:
L µ invariant mass bin Dw
More background
SuperB 06

30. from threshold up to 3 GeV
cos qp distributions
from threshold up to 3 GeV
Histograms show contribution
from GM (dashed)
GE (dash-dotted)
Transition
from sin2q (GE dominant)
to cos2q (GM “ )
SuperB 06

31. APPLE: (LEAR) 2.05 0.7 ± 0.3 FENICE + DM2: 2.1 5.4 ± 4.1 (Adone) (DCI)
1.92 GeV ± 0.5
APPLE:
(LEAR) ± 0.3
FENICE + DM2: ± 4.1
(Adone) (DCI)
E835: ± 0.6
(FNAL)
SuperB 06

32. B+  K+ p p
Bo  Do p p
SuperB 06

33. FENICE n n typical event
SuperB 06

34. Testing the method by means of Fp, assumed like pp:
Space+Time-like data: it might be possible to solve the dispersion relation equations to get the FF in between
(unphysical region)
A model-independent attempt to solve the integral equation by means of a regularization procedure
Testing the method by means of Fp, assumed like pp:
astonishing agreement
Application to GMN (previous data, BaBar ignored):
r(770), r ‘(1600) and threshold : OK
Simplest VDM: GMP(r  pp) ~ mP F(rpp) : OK
But Gr ~ 350 MeV : (?)
SuperB 06

35. T.Massam, A.Zichichi (1966)
SuperB 06

36. Two photons exchange contribution
Blunden-Melnitchouk-Tjon - PRL 91, (2003)
SuperB 06

37. Possible interpretations:
Tail of a narrow resonance below threshold (Baryonium ?)
Dominance of p exchange in pp final state int.
Underestimation of the Coulomb correction factor
Possible tests for “baryonium”:
Narrow vector meson, with vanishing e+e- coupling,
on top of a large r/w recurrence: dip in some cross section
- e+e-  nn (no Coulomb correction)
SuperB 06

38. Dips have indeed been seen in diffractive photoproduction of 6p by E687:
SuperB 06

39. e+e-  Hadrons
SuperB 06

40. Some expectations for s(e+e-  n n) / s(e+e-  p p):
pQCD ~ (qd/qu)2 = 0.25
Soliton models ³ 1
Future perspectives
Very difficult, if not impossible, by means of ISR
p p ® n n , n D ® e+e- (p) at GSI ?
Diffractive Photoproduction g A® (n n)/(p p) A ?
VEPP2000, BEPC2, DAFNE2 ?
SuperB 06

41. Slight evidence for |GEn| << |GMn|
SuperB 06