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02-2-1043-2002/2004
Priority:1
Status: Approved for completion
in 2004

Lifetime Measurement of + - Atoms
to Test Low-Energy QCD Predictions

Leader:   L.L. Nemenov
Deputy: .G. Afanasyev

Scientific Programme:
The DIRAC experiment is aimed to measure the lifetime of + - atoms in the ground state with a 10% precision using the 24 GeV/c proton beam of the CERN Proton Synchrotron. As the value of the above lifetime of the order of 10 -15s is dictated by a strong interaction at low energy, the precise measurement of this quantity enables one to determine a combination of S-wave pion scattering lengths to 5%. Pion scattering lengths have been calculated in the framework of the chiral perturbation theory with a high precision. Thus, the accurate measurement of these values would put the understanding of chiral symmetry breaking of QCD to a crucial test.

Expected main results in 2004:
List of Activities
  Activity or project Spokespersons
Status
DIRAC L.L. Nemenov
Data taking

Collaboration   
Country or international
organization
City Institute or Laboratory
CERN Geneva
Czech Republic Prague CU
IP ASCR
France Paris Univ. VI
Univ. VII
Greece Ioannina UI
Italy Frascatti INFN LNF
Pisa INFN
Trieste INFN
Japan Kyoto KSU
Fukuoka Kyushu Univ.
Tsukuba KEK
Tokyo TM CAE
Romania Bucharest IAP
Russia Moscow SINP MSU
Protvino SRC-IHEP
Spain Santiago de Compostela USC
Switzerland Bern Univ.
Basel Uni Basel

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