Abstract
The NA48/2 experiment at CERN reports the first observation of the K± → π0π0μ±ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV2/c4 is measured to be (0.65 ± 0.03) × 10−6. The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10−6, in agreement with chiral perturbation theory predictions.
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References
S. Weinberg, Phenomenological Lagrangians, Physica A 96 (1979) 327 [INSPIRE].
J. Bijnens, G. Colangelo and J. Gasser, Kl4 decays beyond one loop, Nucl. Phys. B 427 (1994) 427 [hep-ph/9403390] [INSPIRE].
NA48/2 collaboration, Precise tests of low energy QCD from Ke4 decay properties, Eur. Phys. J. C 70 (2010) 635 [INSPIRE].
NA48/2 collaboration, New measurement of the charged kaon semileptonic K± → π+π−e±ν (Ke4) decay branching ratio and hadronic form factors, Phys. Lett. B 715 (2012) 105 [Addendum ibid. 740 (2015) 364] [arXiv:1206.7065] [INSPIRE].
NA48/2 collaboration, Detailed study of the K± → π0π0e±ν (\( {K}_{e4}^{00} \)) decay properties, JHEP 08 (2014) 159 [arXiv:1406.4749] [INSPIRE].
V. Bernard, S. Descotes-Genon and M. Knecht, On some aspects of isospin breaking in the decay K± → π0π0e± \( \overset{\left(-\right)}{v_e} \), Eur. Phys. J. C 75 (2015) 145 [arXiv:1501.07102] [INSPIRE].
G. Colangelo, E. Passemar and P. Stoffer, A dispersive treatment of Kℓ4 decays, Eur. Phys. J. C 75 (2015) 172 [arXiv:1501.05627] [INSPIRE].
V. Bisi, R. Cester, A. Marzari-Chiesa and M. Vigone, K+ rare decay modes, Phys. Lett. B 25 (1967) 572 [INSPIRE].
N. Cabibbo and A. Maksymowicz, Angular correlations in Ke4 decays and determination of low-energy π-π phase shifts, Phys. Rev. 137 (1965) B438 [Erratum ibid. 168 (1968) 1926] [INSPIRE].
NA48/2 collaboration, Search for direct CP violating charge asymmetries in K± → π±π+π− and K± → π±π0π0 decays, Eur. Phys. J. C 52 (2007) 875 [arXiv:0707.0697] [INSPIRE].
B. Peyaud, KABES: a novel beam spectrometer for NA48, Nucl. Instrum. Meth. A 535 (2004) 247 [INSPIRE].
Y. Giomataris, P. Rebourgeard, J.P. Robert and G. Charpak, MICROMEGAS: a high granularity position sensitive gaseous detector for high particle flux environments, Nucl. Instrum. Meth. A 376 (1996) 29 [INSPIRE].
NA48 collaboration, The beam and detector for the NA48 neutral kaon CP violations experiment at CERN, Nucl. Instrum. Meth. A 574 (2007) 433 [INSPIRE].
R. Brun et al., GEANT detector description and simulation tool, CERN-W5013, CERN, Geneva, Switzerland (1994) [https://doi.org/10.17181/CERN.MUHF.DMJ1] [INSPIRE].
Particle Data Group collaboration, Review of particle physics, PTEP 2022 (2022) 083C01 [INSPIRE].
NA48/2 collaboration, Determination of the S-wave ππ scattering lengths from a study of K± → π±π0π0 decays, Eur. Phys. J. C 64 (2009) 589 [arXiv:0912.2165] [INSPIRE].
NA48/2 collaboration, Empirical parameterization of the K± → π±π0π0 decay Dalitz plot, Phys. Lett. B 686 (2010) 101 [arXiv:1004.1005] [INSPIRE].
L. Rosselet et al., Experimental study of 30, 000 Ke4 decays, Phys. Rev. D 15 (1977) 574 [INSPIRE].
Acknowledgments
It is a pleasure to express our appreciation to the staff of the CERN laboratory and the technical staff of the participating laboratories and universities for their efforts in the operation of the experiment and data processing.
The cost of the experiment and its auxiliary systems was supported by the funding agencies of the Collaboration Institutes. We are particularly indebted to: the U.K. Particle Physics and Astronomy Research Council, grant PPA/G/O/1999/00559; the German Federal Minister for Education and Research (BMBF) under contracts 05HK1UM1/1 and 056SI74; the Austrian Ministry for Traffic and Research under the contracts GZ 616.360/2-IV and GZ 616.363/2-VIII, and by the Fonds für Wissenschaft und Forschung FWF Nr. P08929-PHY; INFN (Istituto Nazionale di Fisica Nucleare), Italy; CERN (European Organization for Nuclear Research), Switzerland; ERC (European Research Council) “KaonLepton” starting grant 336581, Europe.
Individuals have received support from: the Bulgarian National Science Fund under contract DID02-22; the Royal Society (grants UF100308, UF0758946), United Kingdom; ERC Starting Grant 336581, Europe.
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ArXiv ePrint: 2310.20295
S. Balev, P.L. Frabetti, E. Gersabeck, E. Goudzovski, P. Hristov, V. Kekelidze, A. Korotkova, V. Kozhuharov, L. Litov, D. Madigozhin, N. Molokanova, I. Polenkevich, Yu. Potrebenikov, S. Stoynev and A. Zinchenko are affiliated with an international laboratory covered by a cooperation agreement with CERN
Deceased (N. Cabibbo, M. Fidecaro, E. Swallow, A. Nappi, G. Pierazzini, L. Widhalm, S. Balev and A. Zinchenko)
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The NA48/2 collaboration., Batley, J.R., Kalmus, G. et al. First observation and study of the K± → π0π0μ±ν decay. J. High Energ. Phys. 2024, 137 (2024). https://doi.org/10.1007/JHEP03(2024)137
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DOI: https://doi.org/10.1007/JHEP03(2024)137