2022 Impact factor 4.4
Particles and Fields
Eur. Phys. J. C 5, 389-409
DOI 10.1007/s100529800974

The neutral kaon decays to $\pi^+$$\pi^-$$\pi^0$:
a detailed analysis of the CPLEAR data

CPLEAR Collaboration
A. Angelopoulos1 - A. Apostolakis1 - E. Aslanides11 - G. Backenstoss2 - P. Bargassa13 - O. Behnke17 - A. Benelli2 - V. Bertin11 - F. Blanc7 - P. Bloch4 - P. Carlson15 - M. Carroll9 - E. Cawley9 - M.B. Chertok3 - M. Danielsson15 - M. Dejardin14 - J. Derre14 - A. Ealet11 - C. Eleftheriadis16 - L. Faravel7 - P. Fassnacht11 - W. Fetscher17 - M. Fidecaro4 - A. Filipcic10 - D. Francis3 - J. Fry9 - E. Gabathuler9 - R. Gamet9 - H.-J. Gerber17 - A. Go4 - A. Haselden9 - P.J. Hayman9 - F. Henry-Couannier11 - R.W. Hollander6 - K. Jon-And15 - P.-R. Kettle13 - P. Kokkas4 - R. Kreuger6 - R. Le Gac11 - F. Leimgruber2 - I. Mandic10 - N. Manthos8 - G. Marel14 - M. Mikuz10 - J. Miller3 - F. Montanet11 - T. Nakada13 - B. Pagels17 - I. Papadopoulos16 - P. Pavlopoulos2 - G. Polivka2 - R. Rickenbach2 - B.L. Roberts3 - T. Ruf4 - M. Schäfer17 - L.A. Schaller7 - T. Schietinger2 - A. Schopper4 - L. Tauscher2 - C. Thibault12 - F. Touchard11 - C. Touramanis9 - C.W.E. Van Eijk6 - S. Vlachos2 - P. Weber17 - O. Wigger13 - M. Wolter17 - D. Zavrtanik10 - D. Zimmerman3

1 University of Athens, Greece
2 University of Basle, Switzerland
3 Boston University, USA
4 CERN, Geneva, Switzerland
5 LIP and University of Coimbra, Portugal
6 Delft University of Technology, Netherlands
7 University of Fribourg, Switzerland
8 University of Ioannina, Greece
9 University of Liverpool, UK
10 J. Stefan Inst. and Phys. Dep., University of Ljubljana, Slovenia
11 CPPM, IN2P3-CNRS et Université d'Aix-Marseille II, France
12 CSNSM, IN2P3-CNRS, Orsay, France
13 Paul Scherrer Institut (PSI), Switzerland
14 CEA, DSM/DAPNIA, CE-Saclay, France
15 Royal Institute of Technology, Stockholm, Sweden
16 University of Thessaloniki, Greece
17 ETH-IPP Zürich, Switzerland

Received: 13 March 1998 / Published online: 3 September 1998

A detailed analysis of neutral kaons decaying to $\pi^{+}\pi^{-}\pi^{0}$ is presented based on the complete data set containing half a million events. Time-dependent decay rate asymmetries are measured between initially tagged ${\mathrm{{K}\mbox{}^0}}$ and ${\mathrm{\overline{K}\mbox{}^0}}$ and for different regions of the phase space. These asymmetries, resulting from the interference between the CP-conserving decay amplitude of ${\mathrm{K_L}}$ and the decay amplitude of ${\mathrm{K_S}}$ - either CP-violating or CP-conserving - allow the determination of the ${\mathrm{K_S}}$ parameters $\eta_{+-0}$ (CP-violating) and $\lambda$ (CP-conserving), and also of the main isospin components of the ${\mathrm{K_S}}$ decay amplitude. The branching ratio of ${\mathrm{K_S}}\rightarrow \pi^{+}\pi^{-}\pi^{0}$ (CP-conserving) is deduced directly from $\lambda$. In addition, we extract the slope parameters describing the energy dependence of the ${\mathrm{K_L}} \rightarrow \pi^{+}\pi^{-}\pi^{0}$ Dalitz plot. The whole set of our results fits well within the current phenomenological picture of the neutral-kaon system including CP violation and Chiral Perturbation Theory (ChPT).

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