Misura di R

Importanza di R QED (M Z ) (g-2) Test di CVC nei decadimenti del Regole di somma di QCD e S

Hadronic contributions to a had (+ ) (+J/, ) (+, )2 > 4 (+KK) < 1.8 GeV a had 2 [ a had ] <1.8 GeV 1% Calculations based on Davier, Eidelman, Höcker, Zhang e+e- data only! 2 contrib. a had 8% [2m p GeV] 54% [ GeV] 10% [Rest<1.8 GeV] r 2 contrib. a had 8% [2m p GeV] 34% [ GeV] 31% [Rest< 1.8 GeV] > 1GeV r

Contribution to had from F. Jegerlehner

Comparison of different evaluations of had had MethodRef data<12 GeVS.Eidelman F.Jegerlehner data<1.8 GeVJ.H.Kuhen, M.Steinhauser data<1.8GeVM.Davier, A.Höcker Euclidean>2.5 GeVF.Jegerlehener scaled data, pQCD , 5- A.D.Martin et al data<12 GeV (new data CMD2 & BES) F.Jegerlehner data<12 GeV (new data CMD2 & BES) H.Burkhardt,B.Pietrzyk 01 ( 05) ( ) up to J/ up to )

magnitudeerrors Burkhardt & Pietrzyk 2001 Contributions to had Including KLOE results, a preliminary analysis of B.& P. found a value of (5) (m Z 2 ) which confirms their 2001 estimate: (5) (m Z 2 ) = ±

Results on R from scan at s<12 GeV PlaceRingDetectorE cm (GeV)ptsYear NovosibirskVEPP-2M VEPP-2 CMD2,SND Olya,ND,CMD < BeijingBEPCBESII OrsayDCIM3N,DMI,DM FrascatiAdone 2,MEA, Boson,BCF SLACSpearMarkI HamburgDorisDASP PLUTO C.Ball LENA , NovosibirskVEPP-4MD

Recent Results from… <1.4CMD2,SNDVEPP-2MNovosibirsk 05, … <10 Gev (via ISR) ( GeV) Babar PEPIISLAC 05<1 (via ISR)KLOE DA NE Frascati YearptsE cm (GeV)DetectorRingPlace Future Projects or Upgrades PlaceRingDetectorE cm (GeV)ptsYear NovosibirskVEPP-2000Upgrades of CMD2 and SND <2 08? BeijingBEPCIIBESIII2-5 06? CornellCESRCLEO-C3-505

Data at 95

Data at 05

After 95 main results were published from CMD2 and and 1)VEPP-2M, Novosibirsk (exclusive measurements) 0.4 <E cm <1.4 GeV –New results on e + e , + - o o ( syst ~7%), e + e o ( syst ~12%), e + e - K S,K L, e + e - + -, + - ( syst ~15%) from CMD2 and SND – e + e from CMD2 with syst ~1.4% published on 99 and with syst ~0.6% ( 0.61<E<0.96 GeV) published on 01 – e + e from SND with syst ~1.3%(hep-ex/ ) BEPC, Beijing (inclusive measurement) 2 <E cm <5 GeV –New result on R in 2 <E cm <5 GeV from BESII coll., with R /R~7% (improvement of a factor 2) - New results on 4 from BES with R /R~10% (presented on Oct 2005 in Frascati) Recent results with energy Scan:

BES: 4 E cm L L Luminosity (nb -1 ) 2( + - )

1)KLOE: – e + e with syst ~1.3% (0.35<E<0.95 GeV 2 ) published on 05 – e + e at threshold is under way (0.1 GeV 2 bin width (5-20 MeV)) 2)BABAR: - e + e between 1. and 3 GeV with syst ~5%-10%published on 05 (25 MeV bin width) - e + e - 4h ( , , ) between 0.6 and 4.5 GeV published on 05: - syst ( ) is 12% ( 3 GeV) - syst ( ) is 15% ( GeV) - syst ( ) is 20% ( GeV) - e + e - 6h (3( + -, 2( + - ) 0 0, 2( + - ) + - ) between 1.5 and 4.5 GeV with syst between 6 and 10% –e + e with syst <=1% is under way Recent/expected results with ISR:

Babar:

Babar: 4h

Babar: 6 3( + - ) 2( + - ) 0 0 Total systematic: ~6-8%Total systematic: ~11%

Babar: 2K4 2( + - )K + K - Total systematic: ~7%

Proiezione a 10 anni Con cosa deve essere competitiva una misura tra 10 anni? Babar... BES... VEPP Altro? La regione 1-2 GeV particolarmente interessante: lerrore attuale ( 15%) contribuisce con un 40% allerrore totale su had

Open issues Buco nella sezione durto multiadronica vicino a soglia p bar-b narrow vector meson resonance, with a mass M 1.87 GeV and a width MeV, consistent with an N bar-N bound state

Open issues Buco di FOCUS nella sezione durto dei 6 Babar conferma in entrambi i canali

Errore percentuale R/R Punti con errore ~3% dalla misura inclusiva di BES ZOOM PRL 84, 594 (2000) – PRL 88, (2002)