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Committee for collaboration of Czech Republic

with Joint Institute for Nuclear Research in Dubna Login
First Measurement of a Long-Lived pi(+) pi(-) Atom Lifetime

Author
Afanasjev , Dr. JINR
Hons Zdeněk, RNDr. CSc.
Nikitin A.N. JINR
et al.  different institutions

Year
2019

Scientific journal
PHYSICAL REVIEW LETTERS 122 (8) 082003

Web


Abstract
The adapted DIRAC experiment at the CERN PS accelerator observed for the first time long-lived hydrogenlike pi(+)pi(-) atoms, produced by protons hitting a beryllium target. A part of these atoms crossed the gap of 96 mm between the target and a 2.1 pm thick platinum foil, in which most of them dissociated. Analyzing the observed number of atomic pairs, n(A)(L) = 436(-61)(+157)vertical bar(tot) the lifetime of the 2p state is found to be QED tau(2p) = (0.45(-0.30)(+1.08) vertical bar(tot)) x 10(-11) s, not contradicting the corresponding QED 2p state lifetime r., -P 1.17 x 10(-11) s. This lifetime value is three orders of magnitude larger than our previously measured value of the pi(+) pi(-) atom ground state lifetime r = (3.15(-0.26)(+0.28)vertical bar(tot)) x 10(-15) s. Further studies of long-lived n-+ atoms will allow us to measure energy differences between p and s atomic states and so to discriminate between the isoscalar and isotensor Kin scattering lengths with the aim to check QCD predictions.

Cite article as:
. Afanasjev, Z. Hons, A. Nikitin, . et al., "First Measurement of a Long-Lived pi(+) pi(-) Atom Lifetime ", PHYSICAL REVIEW LETTERS 122 (8) 082003 (2019)