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Recent results from CMD-3 detector
Peter A. Lukin (on behalf of CMD-3 Collaboration)
Outline


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Introduction Collider & Detector Preliminary Results Conclusion
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Measurement of the cross section e+e- hadrons in the low energy range is interesting for: measurement of parameters of light vector mesons , , , ', '', ', '' test of QCD sum rules, ... etc, search of exotics (light hybrids and glueballs) CVC test in comparison with spectral functions of tau decays measurement of R(s) :

Introduction

(e e * hadrons) R( s ) (e e * )
is essential for the interpretation of precision measurements of: muon (g-2) - good test of SM
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R(s) measurements at low s

The value and the error of the hadronic contribution to muon (g-2) are dominated by low energy R(s) (<2GeV give 92%).
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VEPP-2000 e+e- collider

Main idea: Round Beams

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CMD-3 Detector

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Collinear Events @ CMD-3 (Ec.m. = 1.95 GeV)

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Collected Luminosity

The maximum luminosity is 2·1031 cm-2s-1 at 1.7-1.8 GeV, falling much slower with decreasing energy than before the round beams At high energies luminosity is limited by a deficit of positrons and maximum energy of the booster (900 MeV now)

In 2013 we reached 2 в 160 MeV, the smallest energy ever measured at ee colliders
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Energy measurement by Compton back scattering

E = 993.662±0.016 MeV

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Process

e e 3( )

Phys.Lett. B723 (2013) 82-89

We have very clean selection of 6 and 5 pions

E6-2E

beam

(MeV)

M

miss

2

(MeV2)

Other data for e+e- -> 3(+-)

The best description is with one r(770) and 4 pions in S-wave
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Process e e 2(




)
0

M (MeV)

M (MeV)

wh, fh intermediate states are seen, systematic errors are under study.

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Look at the Process
w(782) f0(980)

e e 2( )


0

Example of wf0(980) signal in w final state.

f0(980)

Detailed analysis is coming...
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Process

e e 2( )

CMD-3 BaBar

We confirm a1(1260) dominance. Some other states ((770)f0(600), (770)f0(980)) are seen.

Statistical errors are at the level of 1-2% per point. Analysis of systematic errors is in progress.

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Study of e e
0

0

w(782)
r .

In addition to dominant w0 and a1 we see rr-, r(770)f0(600)?, r(770)f0(980)

We have statistical errors at the level of 1-2% per point. Systematic errors are under study.
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Preliminary results on e e p p


Cross section

Ratio GE/G

M

from analysis of angular distributions

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Process e e K K

CMD-3 BaBar



K particle identification by dEdX in DC

e e K K

Rich dynamics seen, many intermediate states: K1(1270)K->K*(892)K K1(1400)K->K*(892)K K1(1270)K->KK K*(892)K*(892),
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K*(892)

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Conclusion
New accelerator principles put on the base of the VEPP-2000 collider were successfully proved. First three experimental runs generated considerable amount of data which analysis is in progress now. The second detector, SND, with very good photon detection collected similar statistics and has a lot of various results on hadronic cross sections, particularly on channels with neutrals. The last experimental run ended in the middle of July 2013. Then a long shutdown for 1-1.5 years to increase the booster energy to 1 GeV and commission the new injection complex to reach 1032 cm-2s-1 Hopefully, in the next 5-10 years the VEPP-2000 will produce the integrated luminosity ~ 1 fb-1 which should provide new precise interesting results on the hadron production in e+e- annihilation.

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Stay tuned! Thank You!

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BACKUP SLIDES

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Collected Luminosity
HIGH2011

Data taking history

Scan 1: Ecm = 1.05 ­ 2.0 GeV Scan 2: Ecm = 1.89 ­ 1.075 GeV DEcm = 0.05 GeV, 500 nb-1/point
Ecm = 1.28 ­ 1.98 GeV DEcm = 0.04 GeV, 1000 nb-1/point Ecm = 0.32 ­ 0.98 GeV DEcm = 0.02 GeV, 100 nb-1/point The maximum luminosity is 2·1031 cm-2s-1 at DEcm = 0.002 GeV, 700 nb-1/point 1.7-1.8 GeV, falling much slower with around w(782) peak: decreasing energy than before the round DEcm = 0.002 GeV, 2000 nb-1/point beams @f(1020)/PHI2010-PHI2013/ At high energies luminosity is limited by a deficit of Ecm = 0.984 ­ 1.04 GeV positrons and maximum energy of the booster DEcm = 0.006 GeV,500-1000 nb-1/point (900 MeV now)

HIGH2012 RHO2013

around r(770) peak:

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e e @ CMD-3


1

/point

Ecm = 0.32 ­ 0.98 GeV DEcm = 0.02 GeV, 100

RHO2013

nb

-

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