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

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

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

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 2< s < 5 GeV at ~ 6% level BaBar/BESIII will improve it SuperB 06

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

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

2 mH = nqq -1 + hel.suppres. SuperB 06

s[ e+e- f f0(980) ] SuperB 06

Diffractive photoproduction of 6p by E687: SuperB 06

SuperB 06

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

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

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

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

Time-like |GpE/GpM| SuperB 06

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

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

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

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

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

Cross sections: nn versus pp SuperB 06

Neutron magnetic time-like FF SuperB 06

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

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

SuperB 06

e+e- f h SuperB 06

Early successfull predictions T.Massam, A.Zichichi, NC 43(’66)1137: (J.Ellis, M.Karliner NewJP 4(’02)4) VDM + SU3 + 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

I.S.R. Main Features SuperB 06

I.S.R. versus c.m. Advantages: All energies at the same time  less systematics c.m. boost  e ≠ 0 + sw~ 1 MeV at threshold Drawbacks: L µ invariant mass bin Dw More background SuperB 06

from threshold up to 3 GeV 1.877-1.950 2.4-3.0 cos qp distributions from threshold up to 3 GeV Histograms show contribution from GM (dashed) GE (dash-dotted) Transition from sin2q (GE dominant) to 1+cos2q (GM “ ) SuperB 06

APPLE: (LEAR) 2.05 0.7 ± 0.3 FENICE + DM2: 2.1 5.4 ± 4.1 (Adone) (DCI) 1.92 GeV 1.4 ± 0.5 APPLE: (LEAR) 2.05 0.7 ± 0.3 FENICE + DM2: 2.1 5.4 ± 4.1 (Adone) (DCI) E835: 3.5 0.7 ± 0.6 (FNAL) SuperB 06

B+  K+ p p Bo  Do p p SuperB 06

FENICE n n typical event SuperB 06

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

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

Two photons exchange contribution Blunden-Melnitchouk-Tjon - PRL 91,142304 (2003) SuperB 06

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

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

e+e-  Hadrons SuperB 06

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

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