1,721,014 research outputs found
Search for Leptonic Decays of Dark Photons at NA62
Get PDFThe NA62 experiment at CERN, configured in beam-dump mode, has searched for dark photon decays in flight to electron-positron pairs using a sample of protons on dump collected in 2021. No evidence for a dark photon signal is observed. The combined result for dark photon searches in lepton-antilepton final states is presented and a region of the parameter space is excluded at 90% CL, improving on previous experimental limits for dark photon mass values between 50 and 600 MeV and coupling values in the range to . An interpretation of the search result in terms of the emission and decay of an axion-like particle is also presented
A study of the decay
Get PDFA sample of candidates with
less than 1% background was collected by the NA62 experiment at the CERN SPS in
2017-2018. Branching fraction measurements are obtained at percent relative
precision in three restricted kinematic regions, improving on existing results
by a factor larger than two. An asymmetry, possibly related to T-violation, is
investigated with no evidence observed within the achieved precision
Search for dark photon decays to μ+μ- at NA62
No full textThe NA62 experiment at CERN, designed to study the ultra-rare decay K+ → π+ nu nu-bar, has also collected data in beam-dump mode. In this configuration, dark photons may be produced by protons dumped on an absorber and reach a decay volume beginning 80 m downstream. A search for dark photons decaying in flight to μ+μ- pairs is reported, based on a sample of 1.4 × 10^17 protons on dump collected in 2021. No evidence for a dark photon signal is observed. A region of the parameter space is excluded at 90% CL, improving on previous experimental limits for dark photon masses between 215 and 550 MeV/c^2
Measurement of the decay
No full textA sample of 3984 candidates of the decay, with an estimated background of events, was collected by the NA62 experiment at CERN during 2017-2018. In order to describe the observed di-photon mass spectrum, the next-to-leading order contribution in chiral perturbation theory was found to be necessary. The decay branching ratio in the full kinematic range is measured to be . The first search for production and prompt decay of an axion-like particle with gluon coupling in the process , is also reported
A study of the K+→ π0e+νγ decay
No full textA sample of 1.3 × 10^5 K+ → π0e+νγ candidates with less than 1% background was collected by the NA62 experiment at the CERN SPS in 2017–2018. Branching fraction measurements are obtained at percent relative precision in three restricted kinematic regions, improving on existing results by a factor larger than two. An asymmetry, possibly related to T-violation, is investigated with no evidence observed within the achieved precision
Development of a new CEDAR for kaon identification at the NA62 experiment at CERN
Get PDFThe NA62 experiment at CERN utilises a differential Cherenkov counter with
achromatic ring focus (CEDAR) for tagging kaons within an unseparated
monochromatic beam of charged hadrons. The CEDAR-H detector was developed to
minimise the amount of material in the path of the beam by using hydrogen gas
as the radiator medium. The detector was shown to satisfy the kaon tagging
requirements in a test-beam before installation and commissioning at the
experiment. The CEDAR-H performance was measured using NA62 data collected in
2023.Comment: To be submitted to JINS
Search for leptonic decays of the dark photon at NA62
No full textThe NA62 experiment at CERN, configured in beam-dump mode, has searched for dark photon decays in flight to electron-positron pairs using a sample of protons on dump collected in 2021. No evidence for a dark photon signal is observed. The combined result for dark photon searches in lepton-antilepton final states is presented and a region of the parameter space is excluded at 90% CL, improving on previous experimental limits for dark photon mass values between 50 and 600 MeV and coupling values in the range to . An interpretation of the search result in terms of the emission and decay of an axion-like particle is also presented
Search for K+ decays into the π+e+e−e+e− final state
No full textThe first search for ultra-rare K+ decays into the π+e+e−e+e− final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017–2018. An upper limit of 1.4×10^−8 at 90% CL is obtained for the branching ratio of the K+→π+e+e−e+e− decay, predicted in the Standard Model to be (7.2±0.7)×10^−11. Upper limits at 90% CL are obtained at the level of 10^−9 for the branching ratios of two prompt decay chains involving pair-production of hidden-sector mediators: K+→π+aa, a→e+e− and K+→π+S, S→A′A′, A′→e+e−
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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