Eustachian tube function test as a predictor of middle ear barotrauma

Background: Most of the cases of middle ear barotrauma in divers are due to the impassability of the Eustachian tube. The aim of our study is to compare the results of tympanometry and Valsalva part of Eustachian Tube Function test (ЕТF-test) with the ability of divers to compensate for the change in ambient pressure in a hyperbaric chamber. Material and methods: The study included 35 professional divers undergoing annual medical examination. For all subjects is measured first intratympanal pressure at rest, then after the maneuver of Valsalva with impedancemeter. Then a barofunction test (BFT) was performed to assess the diving fitness and the passability of the Eustachian tubes. It consists of divers compressing and decompressing in a hyperbaric chamber to a pressure of 2.2 ATA for 1 minute. Based on results from previous studies we are using a 20 DaPa cutoff point on the ETF test to predict Eustachian tube passability and a successful barofunction test. Results: In the current study 24 divers have ETF test results higher than 20 DaPa. 3 divers have ETF test values lower than 20 DaPa in both ears, but none of them displayed difficulties in the BFT. 8 divers have ETF values lower than 20 DaPa in one ear and higher than 20 DaPa in the other. 7 of the last group displayed difficulties with the BFT in the ear with poor ETF result. Conclusions: We consider that the ETF test can be used to assess diving fitness as a screening method before performing a BFT, as values above 20 DaPa guarantee Eustachian tube function sufficient for diving activities. Values of 20 DaPa and less are not a definite predictor of the BFT results. The results of the ETF test can also be used in the usual work of an otorhinolaryngologist to evaluate Eustachian function in cases of unilateral disease of middle ear

Search for K+K^+ decays into the π+e+e−e+e−\pi^+e^+e^-e^+e^- final state

International audienceThe first search for ultra-rare $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017-2018. An upper limit of $1.4\times 10^{-8}$ at 90% CL is obtained for the branching ratio of the $K^+\to\pi^+e^+e^-e^+e^-$ decay, predicted in the Standard Model to be $(7.2\pm0.7)\times 10^{-11}$. 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: $K^+\to\pi^+aa$, $a\to e^+e^-$ and $K^+\to\pi^+S$, $S\to A^\prime A^\prime$, $A^\prime\to e^+e^-$. The QCD axion is excluded as a possible explanation of the "17 MeV anomaly"

Measurement of the K+→π+γγK^+\to\pi^+\gamma\gamma decay

International audienceA sample of 3984 candidates of the $K^+\to\pi^+\gamma\gamma$ decay, with an estimated background of $291\pm14$ 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 $(9.61\pm0.17)\times10^{-7}$. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process $K^+\to\pi^+a$, $a\to\gamma\gamma$ is also reported

Measurement of the K+→π+γγK^+\to\pi^+\gamma\gamma decay

International audienceA sample of 3984 candidates of the $K^+\to\pi^+\gamma\gamma$ decay, with an estimated background of $291\pm14$ 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 $(9.61\pm0.17)\times10^{-7}$. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process $K^+\to\pi^+a$, $a\to\gamma\gamma$ is also reported

Measurement of the K+→π+γγK^+ \to \pi^+ \gamma \gamma decay

A sample of 3984 candidates of the $K^+ \to \pi^+ \gamma \gamma$ decay, with an estimated background of $291 \pm 14$ 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 ($9.61 \pm 0.17) \times 10^{−7}$. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process $K^+ \to \pi^+ a, a \to \gamma \gamma$ is also reported.A sample of 3984 candidates of the $K^+\to\pi^+\gamma\gamma$ decay, with an estimated background of $291\pm14$ 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 $(9.61\pm0.17)\times10^{-7}$. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process $K^+\to\pi^+a$, $a\to\gamma\gamma$ is also reported

Measurement of the K+→π+γγK^+\to\pi^+\gamma\gamma decay

International audienceA sample of 3984 candidates of the $K^+\to\pi^+\gamma\gamma$ decay, with an estimated background of $291\pm14$ 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 $(9.61\pm0.17)\times10^{-7}$. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process $K^+\to\pi^+a$, $a\to\gamma\gamma$ is also reported

Search for K+K^+ decays into the π+e+e−e+e−\pi^+e^+e^-e^+e^- final state

The first search for ultra-rare $K^+$ decays into the $\pi^+e^+e^-e^+e^-$ final state is reported, using a dataset collected by the NA62 experiment at CERN in 2017-2018. An upper limit of $1.4\times 10^{-8}$ at 90% CL is obtained for the branching ratio of the $K^+\to\pi^+e^+e^-e^+e^-$ decay, predicted in the Standard Model to be $(7.2\pm0.7)\times 10^{-11}$. 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: $K^+\to\pi^+aa$, $a\to e^+e^-$ and $K^+\to\pi^+S$, $S\to A^\prime A^\prime$, $A^\prime\to e^+e^-$. The QCD axion is excluded as a possible explanation of the '17 MeV anomaly'

Improved calorimetric particle identification in NA62 using machine learning techniques

Measurement of the ultra-rare $K^+\to\pi^+\nu\bar\nu$ decay at the NA62 experiment at CERN requires high-performance particle identification to distinguish muons from pions. Calorimetric identification currently in use, based on a boosted decision tree algorithm, achieves a muon misidentification probability of $1.2\times 10^{-5}$ for a pion identification efficiency of 75% in the momentum range of 15-40 GeV/$c$. In this work, calorimetric identification performance is improved by developing an algorithm based on a convolutional neural network classifier augmented by a filter. Muon misidentification probability is reduced by a factor of six with respect to the current value for a fixed pion-identification efficiency of 75%. Alternatively, pion identification efficiency is improved from 72% to 91% for a fixed muon misidentification probability of $10^{-5}$

A study of the K+→π0e+νγK^+ \to \pi^0 e^+ \nu \gamma decay

International audienceA sample of $1.3 \times 10^5$$K^+ \to \pi^0 e^+ \nu \gamma$ 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

Improved calorimetric particle identification in NA62 using machine learning techniques

International audienceMeasurement of the ultra-rare ${K}^{+}\to {\pi}^{+}\nu \overline{\nu}$ decay at the NA62 experiment at CERN requires high-performance particle identification to distinguish muons from pions. Calorimetric identification currently in use, based on a boosted decision tree algorithm, achieves a muon misidentification probability of 1.2 × 10$^{−5}$ for a pion identification efficiency of 75% in the momentum range of 15–40 GeV/c. In this work, calorimetric identification performance is improved by developing an algorithm based on a convolutional neural network classifier augmented by a filter. Muon misidentification probability is reduced by a factor of six with respect to the current value for a fixed pion-identification efficiency of 75%. Alternatively, pion identification efficiency is improved from 72% to 91% for a fixed muon misidentification probability of 10$^{−5}$