Kaon tagging system and measurement of the K+→π+γγK^+\rightarrow\pi^+ \gamma \gamma decay at the NA62 experiment at CERN

A model-dependent measurement of the branching ratio of the $K^+\rightarrow\pi^+ \gamma \gamma$ decay and a model-independent measurement in bins of the z kinematic variable, performed on the world’s largest data sample, collected by NA62, are presented. In particular, the event selection, the main backgrounds and the addition of an option to bias MC generators to increase the precision of estimates, and the study of systematics are discussed. The combined model-independent branching ratio was found to be $BR_{MI}$ = (0.73 ± 0.04) x 10$^{-6}$. The implementation in the NA62 high-level trigger framework of decoding tools for the STRAW sub-detector, necessary for running trigger algorithms, and of output structures to transfer data to storage is discussed. The performance of the KTAG sub-detector, which has the task of identifying the kaon component in the NA62 secondary beam, is presented. The sub-detector is shown to meet the efficiency requirements during all the 2016-2018 data-taking

Search for Exotic Particles at the NA62 Experiment

The NA62 experiment at the CERN Super Proton Synchrotron (SPS) is currently taking data to measure the ultra-rare decay K + → π + ν ν ¯ . The high-intensity setup, trigger flexibility, detector performance and high-efficiency vetoes make NA62 also suitable for direct searches of long-lived, beyond-the-Standard-Model particles, such as Heavy Neutral Leptons (HNLs), Axion-Like Particles (ALPs) and Dark Photons (DPs); moreover, many rare and forbidden decays are studied at NA62. The status of all these searches is reviewed, together with prospects for future data taking at NA62 after the CERN Long Shutdown 2 (LS2)

Search for Exotic Particles at the NA62 Experiment

The NA62 experiment at the CERN Super Proton Synchrotron (SPS) is currently taking data to measure the ultra-rare decay K + → π + ν ν ¯ . The high-intensity setup, trigger flexibility, detector performance and high-efficiency vetoes make NA62 also suitable for direct searches of long-lived, beyond-the-Standard-Model particles, such as Heavy Neutral Leptons (HNLs), Axion-Like Particles (ALPs) and Dark Photons (DPs); moreover, many rare and forbidden decays are studied at NA62. The status of all these searches is reviewed, together with prospects for future data taking at NA62 after the CERN Long Shutdown 2 (LS2)

Pain assessment and management in Italian Haemophilia Centres

Although the widespread use of factor VIII/IX replacement therapy has significantly reduced the severity of arthropathy in persons with haemophilia (PWH), some develop degenerative joint changes, associated with significant pain. The aim of this survey was to investigate the management and perception of pain among Italian physicians who treat PWH

Search for heavy neutral lepton production in K+K^+ decays

A search for heavy neutral lepton production in $K^+$ decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the $10^{-7}$ to $10^{-6}$ level are established on the elements of the extended neutrino mixing matrix $|U_{\ell 4}|^2$ ($\ell=e,\mu$) for heavy neutral lepton mass in the range $170-448~{\rm MeV}/c^2$. This improves on the results from previous production searches in $K^+$ decays, setting more stringent limits and extending the mass range.A search for heavy neutral lepton production in K+ decays using a data sample collected with a minimum bias trigger by the NA62 experiment at CERN in 2015 is reported. Upper limits at the 10−7 to 10−6 level are established on the elements of the extended neutrino mixing matrix |Ue4|2 and |Uμ4|2 for heavy neutral lepton mass in the ranges 170–448 MeV/ c2 and 250–373 MeV/ c2 , respectively. This improves on the previous limits from HNL production searches over the whole mass range considered for |Ue4|2 , and above 300 MeV/ c2 for |Uμ4|2

First search for K+→π+ννˉK^+\rightarrow\pi^+\nu\bar{\nu} using the decay-in-flight technique

International audienceThe NA62 experiment at the CERN SPS reports the first search for K+→π+νν¯ using the decay-in-flight technique, based on a sample of 1.21×1011 K+ decays collected in 2016. The single event sensitivity is 3.15×10−10 , corresponding to 0.267 Standard Model events. One signal candidate is observed while the expected background is 0.152 events. This leads to an upper limit of 14×10−10 on the K+→π+νν¯ branching ratio at 95% CL

A search for the K+→μ−νe+e+K^+\to\mu^-\nu e^+e^+ decay

A search for the $K^+\to\mu^-\nu e^+e^+$ decay, forbidden within the Standard Model by either lepton number or lepton flavour conservation depending on the flavour of the emitted neutrino, has been performed using the dataset collected by the NA62 experiment at CERN in 2016--2018. An upper limit of $8.1\times 10^{-11}$ is obtained for the decay branching fraction at 90% CL, improving by a factor of 250 over the previous search

Search for lepton number and flavour violation in K+K^+ and π0\pi^0 decays

Searches for the lepton number violating $K^+ \to \pi^− \mu^+ e^+$ decay and the lepton flavour violating $K^+ \to \pi^+ \mu^- e^+$ and $\pi^0 \to \mu^- e^+$ decays are reported using data collected by the NA62 experiment at CERN in 2017$-$2018. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90% confidence level: B($K^+ \to \pi^− \mu^+ e^+$) $K+→π-μ+e+ decay and the lepton flavor violating K+→π+μ-e+ and π0→μ-e+ decays are reported using data collected by the NA62 experiment at CERN in 2017–2018. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90$K^{+} \rightarrow \pi^{-} \mu^{+} e^{+}$decay and the lepton flavour violating$K^{+} \rightarrow \pi^{+} \mu^{-} e^{+}$and$\pi^{0} \rightarrow \mu^{-} e^{+}$decays are reported using data collected by the NA62 experiment at CERN in$2017$-$2018$. No evidence for these decays is found and upper limits of the branching ratios are obtained at 90$\mathcal{B}(K^{+}\rightarrow\pi^{-}\mu^{+}e^{+})<4.2\times 10^{-11}$,$\mathcal{B}(K^{+}\rightarrow\pi^{+}\mu^{-}e^{+})<6.6\times10^{-11}$and$\mathcal{B}(\pi^{0}\rightarrow\mu^{-}e^{+})<3.2\times 10^{-10}$. These results improve by one order of magnitude over previous results for these decay modes