$\mathrm{\cal T}$-violation and $\mathrm{\cal CPT}$-invariance measurements in the CPLEAR experiment: a detailed description of the analysis of neutral-kaon decays to $\mathrm{e} \pi \nu$

The CPLEAR Collaboration; A. Angelopoulos; E. Aslanides; G. Backenstoss; P. Bargassa; O. Behnke; A. Benelli; V. Bertin; F. Blanc; P. Bloch; P. Carlson; M. Carroll; E. Cawley; M.B. Chertok; M. Danielsson; M. Dejardin; J. Derre; A. Ealet; C. Eleftheriadis; W. Fetscher; M. Fidecaro; A. Filipčič; D. Francis; J. Fry; E. Gabathuler; R. Gamet; H.-J. Gerber; A. Go; A. Haselden; P.J. Hayman; F. Henry-Couannier; R.W. Hollander; K. Jon-And; P.-R. Kettle; P. Kokkas; R. Kreuger; R. Le Gac; F. Leimgruber; I. Mandić; N. Manthos; G. Marel; M. Mikuž; J. Miller; F. Montanet; A. Muller T. Nakada; B. Pagels; I. Papadopoulos; P. Pavlopoulos; G. Polivka; R. Rickenbach; B.L. Roberts; T. Ruf; L. Sakeliou; M. Schäfer; L.A. Schaller; T. Schietinger; A. Schopper; L. Tauscher; C. Thibault; F. Touchard; C. Touramanis; C.W.E. Van Eijk; S. Vlachos; P. Weber; O. Wigger; M. Wolter; D. Zavrtanik; D. Zimmerman

doi:doi:10.1007/s100520100793

2022 Impact factor 4.4

Particles and Fields

Eur. Phys. J. C 22, 55-79 (2001)
DOI: 10.1007/s1005201O0793

$\mathrm{\cal T}$ -violation and $\mathrm{\cal CPT}$ -invariance measurements in the CPLEAR experiment: a detailed description of the analysis of neutral-kaon decays to $\mathrm{e} \pi \nu$

The CPLEAR Collaboration¹, A. Angelopoulos¹, E. Aslanides², G. Backenstoss³, P. Bargassa⁴, O. Behnke⁵, A. Benelli³, V. Bertin², F. Blanc^{6, 4}, P. Bloch⁷, P. Carlson⁸, M. Carroll⁹, E. Cawley⁹, M.B. Chertok¹⁰, M. Danielsson⁸, M. Dejardin¹¹, J. Derre¹¹, A. Ealet², C. Eleftheriadis¹², W. Fetscher⁵, M. Fidecaro⁷, A. Filipcic¹³, D. Francis¹⁰, J. Fry⁹, E. Gabathuler⁹, R. Gamet⁹, H.-J. Gerber⁵, A. Go⁷, A. Haselden⁹, P.J. Hayman⁹, F. Henry-Couannier², R.W. Hollander¹⁴, K. Jon-And⁸, P.-R. Kettle⁴, P. Kokkas¹⁵, R. Kreuger¹⁴, R. Le Gac², F. Leimgruber³, I. Mandic¹³, N. Manthos¹⁵, G. Marel¹¹, M. Mikuz¹³, J. Miller¹⁰, F. Montanet², A. Muller T. Nakada^{11, 4}, B. Pagels⁵, I. Papadopoulos¹², P. Pavlopoulos³, G. Polivka³, R. Rickenbach³, B.L. Roberts¹⁰, T. Ruf⁷, L. Sakeliou¹, M. Schäfer⁵, L.A. Schaller⁶, T. Schietinger³, A. Schopper⁷, L. Tauscher³, C. Thibault¹⁶, F. Touchard², C. Touramanis⁹, C.W.E. Van Eijk¹⁴, S. Vlachos³, P. Weber⁵, O. Wigger⁴, M. Wolter⁵, D. Zavrtanik¹³ and D. Zimmerman¹⁰

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

(Received: 24 July 2001 / Published online: 5 October 2001 - © Springer-Verlag / Società Italiana di Fisica 2001 )

Abstract
A detailed description of the analysis of neutral kaons decaying to $\mathrm{e} \pi \nu$ is given, based on the complete set of data collected with the CPLEAR experiment. Using a novel approach involving initially strangeness-tagged K⁰ and $\mathrm{\overline{K}}{}^0$ , time-dependent decay-rate asymmetries were measured. These asymmetries enabled $\mathrm{\cal T}$ - and $\mathrm{\cal CPT}$ -violation parameters to be measured in the context of a systematic study. The highlights of this study are the first direct observation of $\mathrm{\cal T}$ violation and the direct determination of the $\mathrm{\cal CPT}$ parameter $\mathrm{Re}(\delta)$ with an accuracy improved by two orders of magnitude with respect to the current value.