A search for CP violation in Lambda(0)(b) -> pK(-) and Lambda(0)(b) -> p pi(-) decays is presented using the full Run 1 and Run 2 data samples of pp collisions collected with the LHCb detector, corresponding to an integrated luminosity of 9 fb(-1) at center-of-mass energies of 7, 8, and 13 TeV. For the Run 2 data sample, the CPviolating asymmetries are measured to be A(CP)(pK-) = (-1.4 +/- 0.7 +/- 0.4)% and A(CP)(p pi-)= (0.4 +/- 0.9 +/- 0.4)%, where the first uncertainty is statistical and the second is systematic. Following significant improvements in the evaluation of systematic uncertainties compared to the previous LHCb measurement, the Run 1 dataset is reanalyzed to update the corresponding results. When combining the Run 2 and updated Run 1 measurements, the final results are found to be A(CP)(pK-) = (-1.1 +/- 0.7 +/- 0.4)% and A(CP)(p pi-) = (0.2 +/- 0.8 +/- 0.4)%, constituting the most precise measurements of these asymmetries to date.

The first measurement of the CP asymmetry of the decay rate (A(CP)) and the CP average (Sigma A(FB)) and CP asymmetry (Delta A(FB)) of the forward-backward asymmetry in the muon system of Lambda(+)(c) -> p mu(+) mu(-) decays is reported. The measurement is performed using a data sample of proton-proton collisions, recorded by the LHCb experiment from 2016 to 2018 at a center-of-mass energy of 13 TeV, which corresponds to an integrated luminosity of 5.4 fb(-1). The asymmetries are measured in two regions of dimuon mass near the.-meson mass peak. The dimuon-mass integrated results are A(CP) = (-1.1 +/- 4.0 +/- 0.5)%, Sigma A(FB) = (3.9 +/- 4.0 +/- 0.6)%, Delta A(FB) = (3.1 +/- 4.0 +/- 0.4)%, where the first uncertainty is statistical and the second systematic. The results are consistent with the conservation of CP symmetry and the Standard Model expectations.

The first test of lepton flavor universality between muons and electrons using B^{+}→K^{+}π^{+}π^{-}ℓ^{+}ℓ^{-} (ℓ=e, μ) decays is presented. The measurement is performed with data from proton-proton collisions collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9  fb^{-1}. The ratio of branching fractions between B^{+}→K^{+}π^{+}π^{-}e^{+}e^{-} and B^{+}→K^{+}π^{+}π^{-}μ^{+}μ^{-} decays is measured in the dilepton invariant-mass-squared range 1.1<q^{2}<7.0  GeV^{2}/c^{4} and is found to be R_{Kππ}^{-1}=1.31_{-0.17}^{+0.18}(stat) _{-0.09}^{+0.12}(syst), in agreement with the standard model prediction. The first observation of the B^{+}→K^{+}π^{+}π^{-}e^{+}e^{-} decay is also reported.

We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, ω[over ˜]_{p}^{'}, and of the anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From the ratio ω_{a}/ω[over ˜]_{p}^{'}, together with precisely determined external parameters, we determine a_{μ}=116 592 057(25)×10^{-11} (0.21 ppm). Combining this result with our previous result from the 2018 data, we obtain a_{μ}(FNAL)=116 592 055(24)×10^{-11} (0.20 ppm). The new experimental world average is a_{μ}(exp)=116 592 059(22)×10^{-11} (0.19 ppm), which represents a factor of 2 improvement in precision.

We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon g-2 Experiment for the positive muon magnetic anomaly a_{μ}≡(g_{μ}-2)/2. The anomaly is determined from the precision measurements of two angular frequencies. Intensity variation of high-energy positrons from muon decays directly encodes the difference frequency ω_{a} between the spin-precession and cyclotron frequencies for polarized muons in a magnetic storage ring. The storage ring magnetic field is measured using nuclear magnetic resonance probes calibrated in terms of the equivalent proton spin precession frequency ω[over ˜]_{p}^{'} in a spherical water sample at 34.7 °C. The ratio ω_{a}/ω[over ˜]_{p}^{'}, together with known fundamental constants, determines a_{μ}(FNAL)=116 592 040(54)×10^{-11} (0.46 ppm). The result is 3.3 standard deviations greater than the standard model prediction and is in excellent agreement with the previous Brookhaven National Laboratory (BNL) E821 measurement. After combination with previous measurements of both μ^{+} and μ^{-}, the new experimental average of a_{μ}(Exp)=116 592 061(41)×10^{-11} (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.

This paper presents the beam dynamics systematic corrections and their uncertainties for the Run-1 dataset of the Fermilab Muon g - 2 Experiment. Two corrections to the measured muon precession frequency omega(m)(a) are 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 designed RC time 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 to omega(m)(a) is 0.50 +/- 0.09 ppm; the uncertainty is small compared to the 0.43 ppm statistical precision of omega(m)(a).

In high energy physics experiments, calorimeters are calibrated to produce precise and accurate results. Laser light can be used for calibration when the detectors are sensitive to photons in that particular energy range, which is often the case. Moreover, it is not unusual that detection systems consist of hundreds of channels that have to be calibrated independently, which produce stringent requirements on the light distribution system in terms of temporal and spatial stability, energy distribution and timing. Furthermore, the economic factor and the ease of production have to be taken into account. We present a prototype light distribution system, based on a series of optical beamsplitters, developed for the Muon g-2 experiment at Fermilab.