Abstract

We report on the measurement of the direct emission (DE) and interference (INT) terms of the K±→π±π0γ decay by the NA48/2 experiment at the CERN SPS. From the data collected during 2003 and 2004 about 600k such decay candidates have been selected. The relative amounts of DE and INT with respect to the internal bremsstrahlung (IB) contribution have been measured in the range \(0<T^{*}_{\pi }<80\) MeV: \[\begin{array}{l}\mathrm{Frac_{\mathrm{DE}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\[3pt]\quad =(3.32\pm0.15_{\mathrm{stat}}\pm 0.14_{\mathrm{sys}})\times10^{-2},\\[3pt]\mathrm{Frac_{\mathrm{INT}}}{(0<T^{*}_{\pi }<80~\mathrm{MeV})}\\[3pt]\quad =(-2.35\pm 0.35_{\mathrm{stat}}\pm0.39_{\mathrm{sys}})\times10^{-2}\end{array}\] where \(T^{*}_{\pi }\) is the kinetic energy of the charged pion in the kaon rest frame. This is the first observation of an interference term in K±→π±π0γ decays, thus allowing the normalised electric and magnetic amplitudes to be measured, giving XE=(−24±6) GeV−4, and XM=(254±9) GeV−4.

In addition, a limit on the CP violating asymmetry in the K+ and K− branching ratios for this channel has been determined to be less than 1.5×10−3 at 90% confidence level.

Details

Title
Measurement of the direct emission and interference terms and search for CP violation in the decay K ±→π ± π 0 γ
Author
Batley, J R 1 ; Kalmus, G 1 ; Lazzeroni, C 2 ; Munday, D J 1 ; Slater, M W 1 ; Wotton, S A 1 ; Arcidiacono, R 3 ; Bocquet, G 4 ; Cabibbo, N 5 ; Ceccucci, A 4 ; Cundy, D 6 ; Falaleev, V 4 ; Fidecaro, M 4 ; Gatignon, L 4 ; Gonidec, A 4 ; Kubischta, W 4 ; Norton, A 6 ; Maier, A 4 ; Patel, M 4 ; Peters, A 4 ; Balev, S 7 ; Frabetti, P L 8 ; Goudzovski, E 9 ; Hristov, P 10 ; Kekelidze, V 11 ; Kozhuharov, V 8 ; Litov, L 8 ; Madigozhin, D 8 ; Marinova, E 12 ; Molokanova, N 8 ; Polenkevich, I 8 ; Potrebenikov, Y 8 ; Stoynev, S 13 ; Zinchenko, A 8 ; Monnier, E 14 ; Swallow, E 15 ; Winston, R 15 ; Rubin, P 16 ; Walker, A 17 ; Baldini, W 18 ; A Cotta Ramusino 18 ; Dalpiaz, P 18 ; Damiani, C 18 ; Fiorini, M 19 ; Gianoli, A 18 ; Martini, M 18 ; Petrucci, F 18 ; Savrié, M 18 ; Scarpa, M 18 ; Wahl, H 18 ; Bizzeti, A 20 ; Lenti, M 21 ; Veltri, M 22 ; Calvetti, M 23 ; Celeghini, E 23 ; Iacopini, E 23 ; Ruggiero, G 24 ; Behler, M 25 ; Eppard, K 25 ; Kleinknecht, K 25 ; Marouelli, P 25 ; Masetti, L 26 ; Moosbrugger, U 25 ; C Morales Morales 25 ; Renk, B 25 ; Wache, M 25 ; Wanke, R 25 ; Winhart, A 25 ; Coward, D 27 ; Dabrowski, A 28 ; T Fonseca Martin 29 ; Shieh, M 28 ; Szleper, M 28 ; Velasco, M 28 ; Wood, M D 28 ; Cenci, P 30 ; Petrucci, M C 30 ; Pepe, M 30 ; Anzivino, G 31 ; Imbergamo, E 31 ; Nappi, A 31 ; Piccini, M 31 ; Raggi, M 32 ; Valdata-Nappi, M 31 ; Cerri, C 33 ; Fantechi, R 33 ; Collazuol, G 34 ; DiLella, L 34 ; Lamanna, G 34 ; Mannelli, I 34 ; Michetti, A 34 ; Costantini, F 35 ; Doble, N 35 ; Fiorini, L 36 ; Giudici, S 35 ; Pierazzini, G 35 ; Sozzi, M 35 ; Venditti, S 35 ; Bloch-Devaux, B 37 ; Cheshkov, C 38 ; Chèze, J B 37 ; De Beer, M 37 ; Derré, J 37 ; Marel, G 37 ; Mazzucato, E 37 ; Peyaud, B 37 ; Vallage, B 37 ; Holder, M 39 ; Ziolkowski, M 39 ; Bifani, S 40 ; Biino, C 41 ; Cartiglia, N 41 ; Clemencic, M 3 ; S Goy Lopez 42 ; Marchetto, F 41 ; Dibon, H 43 ; Jeitler, M 43 ; Markytan, M 43 ; Mikulec, I 43 ; Neuhofer, G 43 ; Widhalm, L 43 

1  Cavendish Laboratory, University of Cambridge, Cambridge, UK 
2  Cavendish Laboratory, University of Cambridge, Cambridge, UK; University of Birmingham, Birmingham, UK 
3  Dipartimento di Fisica Sperimentale dell’Università e Sezione dell’INFN di Torino, Torino, Italy; CERN, Genève 23, Switzerland 
4  CERN, Genève 23, Switzerland 
5  CERN, Genève 23, Switzerland; Università di Roma “La Sapienza” e Sezione dell’INFN di Roma, Roma, Italy 
6  CERN, Genève 23, Switzerland; Istituto di Cosmogeofisica del CNR di Torino, Torino, Italy 
7  Scuola Normale Superiore, Pisa, Italy; Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
8  Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
9  University of Birmingham, Birmingham, UK; Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
10  CERN, Genève 23, Switzerland; Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
11  Faculty of Physics, University of Sofia “St. Kl. Ohridski”, Sofia, Bulgaria; Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
12  Sezione dell’INFN di Perugia, Perugia, Italy; Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
13  Northwestern University, Evanston, IL, USA; Joint Institute for Nuclear Research, Dubna, Moscow region, Russia 
14  Centre de Physique des Particules de Marseille, IN2P3-CNRS, Université de la Méditerranée, Marseille, France; The Enrico Fermi Institute, The University of Chicago, Chicago, IL, USA 
15  The Enrico Fermi Institute, The University of Chicago, Chicago, IL, USA 
16  Department of Physics and Astronomy, George Mason University, Fairfax, VA, USA; Department of Physics and Astronomy, University of Edinburgh, Edinburgh, UK 
17  Department of Physics and Astronomy, University of Edinburgh, Edinburgh, UK 
18  Dipartimento di Fisica dell’Università e Sezione dell’INFN di Ferrara, Ferrara, Italy 
19  CERN, Genève 23, Switzerland; Dipartimento di Fisica dell’Università e Sezione dell’INFN di Ferrara, Ferrara, Italy 
20  Dipartimento di Fisica, Università di Modena e Reggio Emilia, Modena, Italy; Sezione dell’INFN di Firenze, Firenze, Italy 
21  Sezione dell’INFN di Firenze, Firenze, Italy 
22  Istituto di Fisica, Università di Urbino, Urbino, Italy; Sezione dell’INFN di Firenze, Firenze, Italy 
23  Dipartimento di Fisica dell’Università e Sezione dell’INFN di Firenze, Firenze, Italy 
24  Scuola Normale Superiore, Pisa, Italy; Dipartimento di Fisica dell’Università e Sezione dell’INFN di Firenze, Firenze, Italy 
25  Institut für Physik, Universität Mainz, Mainz, Germany 
26  Physikalisches Institut, Universität Bonn, Bonn, Germany; Institut für Physik, Universität Mainz, Mainz, Germany 
27  Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA; SLAC, Stanford University, Menlo Park, CA, USA 
28  Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA 
29  Department of Physics and Astronomy, Northwestern University, Evanston, IL, USA; Royal Holloway, University of London, Egham, UK 
30  Sezione dell’INFN di Perugia, Perugia, Italy 
31  Dipartimento di Fisica dell’Università e Sezione dell’INFN di Perugia, Perugia, Italy 
32  Dipartimento di Fisica dell’Università e Sezione dell’INFN di Perugia, Perugia, Italy; Laboratori Nazionali di Frascati, Frascati (Rome), Italy 
33  Sezione dell’INFN di Pisa, Pisa, Italy 
34  Scuola Normale Superiore e Sezione dell’INFN di Pisa, Pisa, Italy 
35  Dipartimento di Fisica dell’Università e Sezione dell’INFN di Pisa, Pisa, Italy 
36  Dipartimento di Fisica dell’Università e Sezione dell’INFN di Pisa, Pisa, Italy; Institut de Física d’Altes Energies, UAB, Bellaterra (Barcelona), Spain 
37  DSM/IRFU, CEA Saclay, Gif-sur-Yvette, France 
38  DSM/IRFU, CEA Saclay, Gif-sur-Yvette, France; CERN, Genève 23, Switzerland 
39  Fachbereich Physik, Universität Siegen, Siegen, Germany 
40  Dipartimento di Fisica Sperimentale dell’Università e Sezione dell’INFN di Torino, Torino, Italy; School of Physics Belfield, University College Dublin, Dublin 4, Ireland 
41  Dipartimento di Fisica Sperimentale dell’Università e Sezione dell’INFN di Torino, Torino, Italy 
42  Dipartimento di Fisica Sperimentale dell’Università e Sezione dell’INFN di Torino, Torino, Italy; Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Madrid, Spain 
43  Österreichische Akademie der Wissenschaften, Institut für Hochenergiephysik, Wien, Austria 
Pages
75-87
Publication year
2010
Publication date
Jul 2010
Publisher
Springer Nature B.V.
ISSN
14346044
e-ISSN
14346052
Source type
Scholarly Journal
Language of publication
English
DOI
https://doi.org/10.1140/epjc/s10052-010-1349-8
ProQuest document ID
2294034403
Copyright
The European Physical Journal C is a copyright of Springer, (2010). All Rights Reserved., © 2010. This work is published under https://creativecommons.org/licenses/by-nc/2.0 (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.