Search for pi(0) decays to invisible particles

Gil, E Cortina, Kleimenova, A, Minucci, E, Padolski, S, Petrov, P, Shaikhiev, A, Volpe, R, Numao, T, Velghe, B, Bryman, D
et al (show 190 more authors) (2021) Search for pi(0) decays to invisible particles. JOURNAL OF HIGH ENERGY PHYSICS, 2021 (2).

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<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>The NA62 experiment at the CERN SPS reports a study of a sample of 4 × 10<jats:sup>9</jats:sup> tagged <jats:italic>π</jats:italic><jats:sup>0</jats:sup> mesons from <jats:italic>K</jats:italic><jats:sup>+</jats:sup> → <jats:italic>π</jats:italic><jats:sup>+</jats:sup><jats:italic>π</jats:italic><jats:sup>0</jats:sup>(<jats:italic>γ</jats:italic>), searching for the decay of the <jats:italic>π</jats:italic><jats:sup>0</jats:sup> to invisible particles. No signal is observed in excess of the expected background fluctuations. An upper limit of 4<jats:italic>.</jats:italic>4 × 10<jats:sup><jats:italic>−</jats:italic>9</jats:sup> is set on the branching ratio at 90% confidence level, improving on previous results by a factor of 60. This result can also be interpreted as a model- independent upper limit on the branching ratio for the decay <jats:italic>K</jats:italic><jats:sup>+</jats:sup> → <jats:italic>π</jats:italic><jats:sup>+</jats:sup><jats:italic>X</jats:italic>, where <jats:italic>X</jats:italic> is a particle escaping detection with mass in the range 0.110–0.155 GeV<jats:italic>/c</jats:italic><jats:sup>2</jats:sup> and rest lifetime greater than 100 ps. Model-dependent upper limits are obtained assuming <jats:italic>X</jats:italic> to be an axion-like particle with dominant fermion couplings or a dark scalar mixing with the Standard Model Higgs boson.</jats:p>

Item Type: Article
Uncontrolled Keywords: Beyond Standard Model, Exotics, Fixed target experiments, Rare decay
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 21 Apr 2021 10:26
Last Modified: 18 Jan 2023 22:51
DOI: 10.1007/JHEP02(2021)201
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