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The Nab experiment will measure the correlation a between the momenta of the beta particle and antineutrino in neutron decay as well as the Fierz term b which distorts the beta spectrum.

Angiotensin-receptor blockers (ARBs) are effective treatments for patients with heart failure, but the relation between dose and clinical outcomes has not been explored. We compared the effects of high-dose versus low-dose losartan on clinical outcomes in patients with heart failure. This double-blind trial was undertaken in 255 sites in 30 countries. 3846 patients with heart failure of New York Heart Association class II–IV, left-ventricular ejection fraction 40% or less, and intolerance to angiotensin-converting-enzyme (ACE) inhibitors were randomly assigned to losartan 150 mg (n=1927) or 50 mg daily (n=1919). Allocation was by block randomisation stratified by centre and presence or absence of β-blocker therapy, and all patients and investigators were masked to assignment. The primary endpoint was death or admission for heart failure. Analysis was by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00090259. Six patients in each group were excluded because of poor data quality. With 4·7-year median follow-up in each group (IQR 3·7–5·5 for losartan 150 mg; 3·4–5·5 for losartan 50 mg), 828 (43%) patients in the 150 mg group versus 889 (46%) in the 50 mg group died or were admitted for heart failure (hazard ratio [HR] 0·90, 95% CI 0·82–0·99; p=0·027). For the two primary endpoint components, 635 patients in the 150 mg group versus 665 in the 50 mg group died (HR 0·94, 95% CI 0·84–1·04; p=0·24), and 450 versus 503 patients were admitted for heart failure (0·87, 0·76–0·98; p=0·025). Renal impairment (n=454 vs 317), hypotension (203 vs 145), and hyperkalaemia (195 vs 131) were more common in the 150 mg group than in the 50 mg group, but these adverse events did not lead to significantly more treatment discontinuations in the 150 mg group. Losartan 150 mg daily reduced the rate of death or admission for heart failure in patients with heart failure, reduced left-ventricular ejection fraction, and intolerance to ACE inhibitors compared with losartan 50 mg daily. These findings show the value of up-titrating ARB doses to confer clinical benefit. Merck (USA).

This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muong−2Experiment. Two corrections to the measured muon precession frequencyωamare associated with well-known effects owing to the use of electrostatic quadrupole (ESQ) vertical focusing in the storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through the radial electric field components created by the ESQ system. The correction depends on the stored momentum distribution and the tunes of the ring, which has relatively weak vertical focusing. Vertical betatron motions imply that the muons do not orbit the ring in a plane exactly orthogonal to the vertical magnetic field direction. A correction is necessary to account for an average pitch angle associated with their trajectories. A third small correction is necessary, because muons that escape the ring during the storage time are slightly biased in initial spin phase compared to the parent distribution. Finally, because two high-voltage resistors in the ESQ network had longer than designedRCtime constants, the vertical and horizontal centroids and envelopes of the stored muon beam drifted slightly, but coherently, during each storage ring fill. This led to the discovery of an important phase-acceptance relationship that requires a correction. The sum of the corrections toωamis0.50±0.09ppm; the uncertainty is small compared to the 0.43 ppm statistical precision ofωam.

The international PEN collaboration aims to obtain the branching ratio for the pion electronic decay \\(\\pi^+ \\to e^+\\nu_e(\\gamma)\\), aka \\(\\pi_{e2}\\), to a relative precision of \\(5\\times 10^{-4}\\) or better. The PEN apparatus comprises a number of detection systems, all contributing vital information to the PEN event reconstruction. This paper discusses the design, performance, and Monte Carlo simulation of the mini time projection chamber (mTPC) used for pion, muon, and positron beam particle tracking. We also review the use of the extracted trajectory coordinates in the analysis, in particular in constructing observables critical for discriminating background processes, and in maximizing the fiducial volume of the target in which decay event vertices can be accepted for branching ratio extraction without introducing bias.

PIONEER is a rapidly developing effort aimed to perform a pristine test of lepton flavour universality (LFU) and of the unitarity of the first row of the CKM matrix by significantly improving the measurements of rare decays of the charged pion. In Phase I, PIONEER aims to measure the charged-pion branching ratio to electrons vs.\\ muons \\(R_{e/\\mu}\\) to 1 part in \\(10^4\\), improving the current experimental result \\(R_{e/\\mu}\\,\\text{(exp)} =1.2327(23)\\times10^{-4}\\) by a factor of 15. This precision on \\(R_{e/\\mu}\\) will match the theoretical accuracy of the SM prediction allowing for a test of LFU at an unprecedented level, probing non-SM explanations of LFU violation through sensitivity to quantum effects of new particles up to the PeV mass scale. Phase II and III will aim to improve the experimental precision of the branching ratio of pion beta decay, \\(\\pi^+\\to \\pi^0 e^+ \\nu (\\gamma)\\), currently at \\(1.036(6)\\times10^{-8}\\), by a factor of three and six, respectively. The improved measurements will be used to extract \\(V_{ud}\\) in a theoretically pristine manner. The ultimate precision of \\(V_{ud}\\) is expected to reach the 0.05\\,\\% level, allowing for a stringent test of CKM unitarity. The PIONEER experiment will also improve the experimental limits by an order of magnitude or more on a host of exotic decays that probe the effects of heavy neutrinos and dark sector physics. This input to the 2026 update of the European Strategy for Particle Physics Strategy describes the physics motivation and the conceptual design of the PIONEER experiment, and is prepared based on the PIONEER proposal submitted to and approved with high priority by the PSI program advisory committee (PAC). Using intense pion beams, and state-of-the-art instrumentation and computational resources, the PIONEER experiment is aiming to begin data taking by the end of this decade.

We are developing an experiment to measure the correlations a, A, and B, and the Fierz interference term b in neutron decay, with a precision of approximately 10(-4). The experiment uses an electromagnetic spectrometer in combination with two large-area segmented silicon detectors to detect the proton and electron from the decay in coincidence, with 4π acceptance for both particles. For the neutron-polarization-dependent observables A and B, precision neutron polarimetry is achieved through the combination of a pulsed neutron beam, under construction at the SNS, and a polarized (3)He neutron polarizer. Measuring a and A in the same apparatus provides a redundant determination of λ = gA/gV . Uncertainty in λ dominates the uncertainty of CKM unitarity tests.

Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, \\(\\lambda = g_A / g_V\\), through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter \\(a\\) with a precision of \\(\\delta a / a = 10^{-3}\\) and the Fierz interference term \\(b\\) to \\(\\delta b = 3\\times10^{-3}\\) in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio \\(\\lambda\\) with a precision of \\(\\delta \\lambda / \\lambda = 0.03\\%\\) that will allow an evaluation of \\(V_{ud}\\) and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.

We report interim results of the PIBETA experiment analysis for the pion beta decay and pion radiative decay. The former is in excellent agreement with the SM predictions at the 1% accuracy level.

We are developing an experiment to measure the correlations a, A, and B, and the Fierz interference term b in neutron decay, with a precision of approximately 10-4. The experiment uses an electromagnetic spectrometer in combination with two large-area segmented silicon detectors to detect the proton and electron from the decay in coincidence, with 4pi acceptance for both particles. For the neutron-polarization-dependent observables A and B, precision neutron polarimetry is achieved through the combination of a pulsed neutron beam, under construction at the SNS, and a polarized 3He neutron polarizer. Measuring a and A in the same apparatus provides a redundant determination of lambda = gA/gv. Uncertainty in 2 dominates the uncertainty of CKM unitarity tests.

Neutron beta decay is one of the most fundamental processes in nuclear physics and provides sensitive means to uncover the details of the weak interaction. Neutron beta decay can evaluate the ratio of axial-vector to vector coupling constants in the standard model, λ = g A / g V , through multiple decay correlations. The Nab experiment will carry out measurements of the electron-neutrino correlation parameter a with a precision of δ a / a = 10 −3 and the Fierz interference term b to δ b = 3 × 10 −3 in unpolarized free neutron beta decay. These results, along with a more precise measurement of the neutron lifetime, aim to deliver an independent determination of the ratio λ with a precision of δλ/λ = 0.03% that will allow an evaluation of V ud and sensitively test CKM unitarity, independent of nuclear models. Nab utilizes a novel, long asymmetric spectrometer that guides the decay electron and proton to two large area silicon detectors in order to precisely determine the electron energy and an estimation of the proton momentum from the proton time of flight. The Nab spectrometer is being commissioned at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source at Oak Ridge National Lab. We present an overview of the Nab experiment and recent updates on the spectrometer, analysis, and systematic effects.