A sample of 3984 candidates of the K+→π+γγ decay, with an estimated background of 291±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±0.17)×10−7. The first search for production and prompt decay of an axion-like particle with gluon coupling in the process K+→π+a, a→γγ is also reported.

AbstractAimsThis study aimed to examine the diagnostic pathways and outcomes of patients with heart failure (HF), stratified by left ventricular ejection fraction (EF), and to highlight deficiencies in real‐world HF diagnosis and management.Methods and resultsWe conducted a retrospective cohort study in Salford, United Kingdom, utilizing linked primary and secondary care data for HF patients diagnosed between January 2010 and November 2019. We evaluated characteristics, diagnostic patterns, healthcare resource utilization, and outcomes. Patients were categorized according to baseline (the latest measure prior to or within 90 days post‐diagnosis) as having HF with reduced EF (HFrEF), mildly reduced EF (HFmrEF), or preserved EF (HFpEF). The data encompassed a 2 year period before diagnosis and up to 5 years post‐diagnosis. A total of 3227 patients were diagnosed with HF between January 2010 and November 2019. The mean follow‐up time was 2.6 [±1.9 standard deviation (SD)] years. The mean age at diagnosis was 74.8 (±12.7 SD) years, and 1469 (45.5%) were female. HFpEF was the largest cohort (46.6%, npEF = 1505), HFmrEF constituted 16.1% (nmrEF = 520), and HFrEF 18.5% (nrEF = 596) of the population, while 18.8% (nu = 606) of patients remained unassigned due to insufficient evidence to support categorization. At baseline, measurement of natriuretic peptide (NP; brain NP and N‐terminal pro‐B‐type NP) and echocardiographic report data were available for 592 (18.3%) and 2621 (81.2%) patients, respectively. A total of 2099 (65.0%) of the HF cohort had access to a cardiology‐led outpatient clinic prior to the HF diagnosis, and 602 (18.7%) attended cardiac rehabilitation post‐diagnosis. The 5 year crude survival rate was 37.8% [95% confidence interval (CI) (35.2–40.7%)], 42.3% [95% CI (38.0–47.2%)], and 45.5% [95% CI (41.0–50.4%)] for HFpEF, HFrEF, and HFmrEF, respectively.ConclusionsLow survival rates were observed across all HF groups, along with suboptimal rates of NP testing and specialist assessments. These findings suggest missed opportunities for timely and accurate HF diagnosis, a pivotal first step in improving outcomes for HF patients. Addressing these gaps in diagnosis and management is urgently needed.

Recent results from searches for rare kaon decays with the NA62 experiment at CERN are reported, together with the future prospects. A future experiment HIKE, to go beyond NA62, has been proposed to push kaon physics to an unprecedented frontier. The HIKE timescale and expected performance are described. Among the NA62 results, the measurement of the branching ratios of the flavour changing neutral current $K^+\rightarrow\pi^+\mu^+\mu^-$ and the radiative non leptonic $K^+\rightarrow\pi^+\gamma\gamma$ decays are reported, upper limits are given for lepton flavor and lepton number violating decays $K^+\rightarrow\mu^-\nu e^+e^+$ and $K^+\rightarrow\pi^-\pi^0 e^+e^+$. A search for new physics in the branching ratio of the decay $K^+\rightarrow\pi^+ e^+e^-e^+e^-$ is presented

The first search for the lepton number violating decay K+ -> pi(0)pi(-)mu(+)e(+) and lepton flavour violating decays K+ -> pi(0)pi(+)mu-e(+), K+ -> pi(0)pi(+)mu(+)e(-) has been performed using a dataset collected by the NA62 experiment at CERN in 2016-2018. Upper limits of 2.9 x 10(-10), 3.1 x 10(-10) and 5.0 x 10(-10), respectively, are obtained at 90% CL for the branching ratios of the three decays on the assumption of uniform phase-space distributions.

The 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−.

The flavor-changing neutral current decay [Formula: see text] ([Formula: see text]) is well suited to explore the Standard Model structure. A new measurement of this decay branching fraction and form factor has been performed by the NA62 experiment at CERN based on data collected in 2017–2018. From the selected sample of 28011 [Formula: see text] event candidates with a negligible background, the decay form factor parameters [Formula: see text] and [Formula: see text], as well as the branching fraction [Formula: see text] have been measured.

We report the results of a search for dark photon in-flight decays to μ + μ − pairs at NA62. Dark photons could be produced by dumping protons onto a copper-iron absorber, reach the NA62 decay volume more than 80 m downstream of the dump and decay therein. The measurement is based on data collected in 2021 which correspond to 1.4 × 1017 dumped protons.

The K+ -> pi(+) nu(nu) over bar decay, with a very precisely predicted branching ratio of less than 10(-10), is among the best processes to reveal indirect effects of new physics. The NA62 experiment reports the branching ratio measurement BR(K+ -> pi(+) nu(nu) over bar) = (1.06(-0.34)(+0.40)vertical bar(stat) +/- 0.09 vertical bar syst) . 10(-10) at 68% CL, based on the observation of 20 signal candidates with an expected background of 7.0 events from the total data sample collected at the CERN SPS during 2016-2018. This provides evidence for the very rare K+ -> pi(+)nu(nu) over bar decay, observed with a significance of 3.4 sigma. This measurement is also used to set limits on BR(K+ -> pi(+) X), where X is a new feebly interacting scalar or pseudo-scalar particle, foreseen in several new physics scenarios.

Measurement of the ultra-rare K^+→π^+νν 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

A search for the K+ -> mu(-)ve(+)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 x 10(-11) is obtained for the decay branching fraction at 90% CL, improving by a factor of 250 over the previous search. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/). Funded by SCOAP(3).

The NA62 experiment at CERN targets the measurement of the ultra-rare K^+→π^+νν decay, and carries out a broad physics programme that includes probes for symmetry violations and searches for exotic particles. Data were collected in 2016–2018 using a multi-level trigger system, which is described highlighting performance studies based on 2018 data.

A sample of 1.3 x 10(5)K+? p(0)e(+)?? 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.

Abstract A sample of 1.3 × 105 K + → π 0 e + 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.

Using data from patients residing in Salford, UK, we aimed to compare healthcare resource utilisation (HCRU) and direct healthcare costs between patients with moderate to severe (M-S) or severe osteoarthritis (OA) pain and those without OA. Patients with a M-S OA pain event within a period of chronic pain were indexed from the Salford Integrated Record (SIR) between 2010 and 2017. Patients with a severe pain event formed an OA subcohort. Patients in each OA pain cohort were independently matched to patients without OA, forming two control cohorts. HCRU, prescribed analgesic drugs, and total direct costs per UK standardised tariffs were calculated for the year post-index. Multivariable models were used to identify drivers of healthcare cost. The M-S OA pain and control cohorts each comprised 3123 patients; the severe OA pain and control cohorts each comprised 1922 patients. Patients in both OA pain cohorts had a significantly higher mean number of general practitioner encounters, inpatient, outpatient, and accident and emergency visits, and were prescribed a broader range of analgesic drugs in the year post-index than respective controls. Mean healthcare costs of all types were significantly higher in the M-S and severe OA pain cohorts vs controls (total: M-S £2519 vs £1379; severe £3389 vs £1397). Paracetamol (M-S: 40% of patients had at least one prescription; severe: 50%) and strong opioids (34% and 59%) were the analgesics most prescribed to patients with OA pain. In all cohorts, multivariable models showed that a higher age at index, the presence of gout, osteoporosis, type 2 diabetes, or coronary artery disease, significantly contributed towards higher healthcare costs. In the population of Salford, UK, patients with M-S OA pain had significantly higher annual HCRU and costs compared with matched controls without OA; generally, these were even higher in patients with severe OA pain.

The K+→π+νν¯ decay, with a very precisely predicted branching ratio of less than 10−10, is among the best processes to reveal indirect effects of new physics. The NA62 experiment reports the branching ratio measurement BR( K+→π+νν¯ ) = 1.06−0.34+0.40|stat ± 0.009| syst ) · 10−10 at 68% CL, based on the observation of 20 signal candidates with an expected background of 7.0 events from the total data sample collected at the CERN SPS during 2016-2018. This provides evidence for the very rare K+→π+νν¯ decay, observed with a significance of 3.4σ. This measurement is also used to set limits on BR(K + → π +X), where X is a new feebly interacting scalar or pseudo-scalar particle, foreseen in several new physics scenarios.

A sample of 2.8 x 10(4) K+ -> pi(+)mu(+)mu(-) candidates with negligible background was collected by the NA62 experiment at the CERN SPS in 2017-2018. The model-independent branching fraction is measured to be (9.15 +/- 0.08) x 10(-8), a factor three more precise than previous measurements. The decay form factor is presented as a function of the squared dimuon mass. A measurement of the form factor parameters and their uncertainties is performed using a description based on Chiral Perturbation Theory at O (p(6)).