THEME02-2-1080-2009/2013

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02-2-1080-2009/2013

Priority:

Status:

Extended

Lifetime Measurement ⁺ ^- and ^± K Atoms
to Test Low-Energy QCD Precise Predictions

Leader:	L.G. Afanasyev
Scientific leader:	L.L. Nemenov

Participating Countries, Institutes and International organizations:
CERN, Czech Republic, Italy, Japan, Romania, Russia, Spain, Switzerland.
Scientific Programme:
The experiment aims to measure the lifetime of

⁺

^- atoms (A₂), observe

K atoms (A_K), and measure their lifetime using the 24 GeV proton beam. The precise measurement of these quantities will enable us to determine the combination of s-wave pion-pion |a₀ - a₂| and pion-kaon |a_1/2-a_3/2| scattering lengths (with isospin 0, 2 and 1/2, 3/2, respectively) in a model-independent way. The precision of A₂ lifetime measurement will be better than 6% and the difference |a₀ - a₂| will be determined within 3% or better. The accuracy of A_K lifetime measurement will be at the level of 20% and the difference |a_1/2-a_3/2| will be determined at the level of 10%. Low-energy QCD predicts these values with an accuracy about 2% for the pion-pion scattering lengths and about 10% for the

K scattering lengths. The pion-pion and pion-kaon scattering lengths have never been verified with the experimental data with the same level of precision. For this reason the proposed measurements will be a crucial check of the low-energy QCD predictions and our understanding of the nature of the QCD vacuum.

Expected main results in 2012:

Preparation of the addendum to the DIRAC project on the observation at the existing setup of the atoms formed by ⁺µ ^- and ^-µ ⁺ mesons. Data taking for observation of µ atoms.
Completion of analysis of the 2008-2010 data on the search for K atoms and measurement of their lifetime. Publication of the results.
Completion of the processing of the 2008-2010 data on the search for atom lifetime.
Processing of the data collected in 2011 for observation of the long-lived states of the atom.
Preparation of the project for investigation of , K, µ, KK and µµ atoms of the SPS accelerator, CERN.

List of Activities

Activity or Experiment

Leader

Status

Laboratory and
Responsible person

Main researchers for the Laboratory

Experiment DIRAC

L.G. Afanasyev

Data taking
Data analysis

DLNP

L.G. Afanasyev, M.V. Zhabitsky, A.V. Dudarev, V.V. Kruglov, V.V. Karpukhin, E. Kulish, A.V. Kulikov, L.L. Nemenov, M.V. Nikitin

LIT

P.V. Zrelov, O.V. Voskresenskaya, L.Yu. Kruglova

Collaboration
Country or international organization	City	Institute or Laboratory
CERN	Geneva
Czech Republic	Prague	CTU
		IP ASCR
Italy	Frascati	INFN LNF
	Messina	Univ.
	Trieste	INFN
Japan	Kyoto	KSU
	Tokyo	TMU
	Tsukuba	KEK
Romania	Bucharest	IFA
Russia	Moscow	SINP MSU
	Protvino	IHEP
Spain	Santiago de Compostela	USC
Switzerland	Bern	Uni Bern
	Zurich	UZH

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Lifetime Measurement + - and ± K Atoms to Test Low-Energy QCD Precise Predictions

Lifetime Measurement ⁺ ^- and ^± K Atoms
to Test Low-Energy QCD Precise Predictions