Misura di R

1
Misura di R
2
Importanza di R

• aQED(MZ)
• (g-2)m
• Test di CVC nei decadimenti del t
• Regole di somma di QCD e aS

3
Hadronic contributions to amhad
Calculations based on Davier, Eidelman, Höcker,
Zhang
a?had
lt1.8 GeV
?2a?had
lt1.8 GeV
1
ee- data only!
4
Contribution to Da(5)had from F. Jegerlehner
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Comparison of different evaluations of Da(5)had
Da(5)had Method Ref
0.0280 ?0.00065 datalt12 GeV S.Eidelman F.Jegerlehner 95
0.02777 ? 0.00017 datalt1.8 GeV J.H.Kuhen, M.Steinhauser 98
0.02763 ?0.00016 datalt1.8GeV M.Davier, A.Höcker 98
0.027730?0.000148 Euclideangt2.5 GeV F.Jegerlehener 99
0.027426?0.000190 scaled data, pQCD 2.8-3.7, 5-? A.D.Martin et al. 00
0.027896?0.000391 datalt12 GeV (new data CMD2 BES) F.Jegerlehner 01
0.02761 ? 0.00036 datalt12 GeV (new data CMD2 BES) H.Burkhardt,B.Pietrzyk 01 ( 05)
0.00007 (0.00005) ds1 up to J/y (ds1 up to ?)
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Burkhardt Pietrzyk 2001
Contributions to Dahad
magnitude
errors
Including KLOE results, a preliminary analysis of
B. P. found a value of Da(5)(mZ2) which confirms
their 2001 estimate Da(5)(mZ2) 0.027610.00036
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Results on R from scan at ?slt12 GeV
Place Ring Detector Ecm(GeV) pts Year
Novosibirsk VEPP-2M VEPP-2 CMD2,SND Olya,ND,CMD lt1.4 lt1.4 128 97-99 79-85
Beijing BEPC BESII 2-5 85 98-99
Orsay DCI M3N,DMI,DM2 1.35-2.13 33 78
Frascati Adone gg2,MEA, Boson,BCF 1.42-3.09 31 78
SLAC Spear MarkI 2.8-7.8 78 82
Hamburg Doris DASP PLUTO C.Ball LENA 3.1-5.2 3.6-4.8,9.46 5.0-7.4 7.4-9.4 64 27 11 95 79 77 90 82
Novosibirsk VEPP-4 MD-1 7.23-10.34 30 91
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Recent Results from
Year
pts
Ecm(GeV)
Detector
Ring
Place
01 03
128
lt1.4
CMD2,SND
VEPP-2M
Novosibirsk
05
lt1 (via ISR)
KLOE
DAFNE
Frascati
05,
lt10 Gev (via ISR) (0.5-4.5 GeV)
Babar
PEPII
SLAC
Future Projects or Upgrades
Place Ring Detector Ecm(GeV) pts Year
Novosibirsk VEPP-2000 Upgrades of CMD2 and SND lt2 08?
Beijing BEPCII BESIII 2-5 06?
Cornell CESR CLEO-C 3-5 05
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Data at 95
10
Data at 05
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Recent results with energy Scan

• After 95 main results were published from CMD2
  and SND _at_VEPP-2M and BESII_at_BEPC
• 1)VEPP-2M, Novosibirsk (exclusive measurements)
  0.4 ltEcmlt1.4 GeV
• New results on ee- ?p p- p p-, p p- po po
  (ssyst7), ee- ?p p- po
• (ssyst12), ee- ?KS,KL, ee- ?w p p-,hp p-
  (ssyst15) from CMD2 and SND
• ee- ?p p- from CMD2 with ssyst1.4 published
  on 99 and with ssyst0.6 ( 0.61ltElt0.96 GeV)
  published on 01
• ee- ?p p- from SND with ssyst1.3(hep-ex/05060
  76)
• 2)BESII _at_ BEPC, Beijing (inclusive measurement)
  2 ltEcmlt5 GeV
• New result on R in 2 ltEcmlt5 GeV from BESII coll.,
  with sR/R7
• (improvement of a factor 2)
• - New results on 4p from BES with sR/R10
  (presented on Oct 2005 in Frascati)

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BES 4p
Luminosity (nb-1)
2(pp-)
Ecm L Ecm L
2.00 45.8?1.4 2.80 89.0 ?1.8
2.20 123.5 ?3.7 2.90 94.0 ?2.6
2.40 61.0 ?1.6 3.00 947 ?22
2.50 47.0 ?1.0 3.07 2272.8 ?36.4
2.60 1231.0 ?14.8 3.65 6450.4 ?90.3
2.70 71.6 ?2.1
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Recent/expected results with ISR

• 1)KLOE
• ee- ?p p- with ssyst1.3 (0.35ltElt0.95 GeV2)
  published on 05
• ee- ?p p- at threshold is under way
• (0.1 GeV2 bin width (5-20 MeV))
• 2)BABAR
• - ee- ?p p- p0 between 1. and 3 GeV with
  ssyst5-10published on 05
• (25 MeV bin width)
• - ee- ? 4h (p p-p p-, p p-K K-, K K-K
  K-) between 0.6 and 4.5 GeV published on 05
• - ssyst(p p-p p-) is 12 (lt1GeV), 5(1.-3
  GeV), 16 (gt3 GeV)
• - ssyst(p p-K K-) is 15 (1.5-4.5 GeV)
• - ssyst(K K-K K-) is 20 (2.0-4.5 GeV)
• - ee- ? 6h (3(p p-), 2(p p-) p0p0, 2(p p-)
  K K-) between 1.5 and 4.5 GeV with ssyst between
  6 and 10
• ee- ?p p- with ssystlt1 is under way

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Babar 3p
pp-p0
15
Babar 4h
16
Babar 6p
3(pp-)
2(pp-)p0p0
Total systematic 6-8
Total systematic 11
17
Babar 2K4p
2(pp-)KK-
Total systematic 7
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Proiezione a 10 anni

• Con cosa deve essere competitiva una misura tra
  10 anni?
• Babar...
• BES...
• VEPP 2000...
• Altro?
• La regione 1-2 GeV particolarmente interessante
  lerrore attuale (?15) contribuisce con un ?40
  allerrore totale su Da(5)had

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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 ? ? 10-20 MeV, consistent
  with an N?bar-N bound state

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Open issues

• Buco di FOCUS nella sezione durto dei 6p
• Babar conferma in entrambi i canali

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Errore percentuale
ZOOM
DR/R
DR/R
Punti con errore 3 dalla misura inclusiva di BES
PRL 84, 594 (2000) PRL 88, 101802 (2002)