We present the first results of the Fermilab National Accelerator Laboratory (FNAL) Muon $g-2$ Experiment for the positive muon magnetic anomaly $a_{\mu }\equiv (g_{\mu }-2)/2$. 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 ${\omega }_a$ 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 ${\tilde{\omega }}_p^{\prime }$ in a spherical water sample at $34.7°\mathrm{C}$. The ratio ${\omega }_a/{\tilde{\omega }}_p^{\prime }$, together with known fundamental constants, determines $a_{\mu }(\mathrm{FNAL})=116\hspace{0.17em}592\hspace{0.17em}040(54)\times {10}^{-11}$ (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 ${\mu }^{+}$ and ${\mu }^{-}$, the new experimental average of $a_{\mu }(\mathrm{Exp})=116\hspace{0.17em}592\hspace{0.17em}061(41)\times {10}^{-11}$ (0.35 ppm) increases the tension between experiment and theory to 4.2 standard deviations.

We study $B\to K^{(*)}{\ell }^{+}{\ell }^{-}$ decays ($\ell =e$, $\mu$) based on a data sample of $657\times {10}^6$ $B\overline{B}$ pairs collected with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. We report the differential branching fraction, isospin asymmetry, $K^{*}$ polarization, and the forward-backward asymmetry ($A_{\mathrm{FB}}$) as functions of $q^2=M_{\ell \ell }^2{c}^2$. The fitted $A_{\mathrm{FB}}$ spectrum exceeds the standard model expectation by 2.7 standard deviations. The measured branching fractions are $\mathcal{B}(B\to K^{*}{\ell }^{+}{\ell }^{-})=({10.7}_{-1.0}^{+1.1}\pm 0.9)\times {10}^{-7}$ and $\mathcal{B}(B\to K{\ell }^{+}{\ell }^{-})=({4.8}_{-0.4}^{+0.5}\pm 0.3)\times {10}^{-7}$, where the first errors are statistical and the second are systematic, with the muon to electron ratios $R_{K^{*}}=0.83\pm 0.17\pm 0.08$ and $R_K=1.03\pm 0.19\pm 0.06$.

The Muon $g-2$ Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency ${\omega }_a^m$ to an uncertainty of 434 parts per billion (ppb), statistical, and 56 ppb, systematic, with data collected in four storage ring configurations during its first physics run in 2018. When combined with a precision measurement of the magnetic field of the experiment’s muon storage ring, the precession frequency measurement determines a muon magnetic anomaly of $a_{\mu }(\mathrm{FNAL})=116\hspace{0.17em}592\hspace{0.17em}040(54)\times {10}^{-11}$ (0.46 ppm). This article describes the multiple techniques employed in the reconstruction, analysis, and fitting of the data to measure the precession frequency. It also presents the averaging of the results from the 11 separate determinations of ${\omega }_a^m$, and the systematic uncertainties on the result.

We report a measurement of the exclusive $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\Lambda }_c^{-}$ cross section as a function of center-of-mass energy near the ${\Lambda }_c^{+}{\Lambda }_c^{-}$ threshold. A clear peak with a significance of $8.2\sigma$ is observed in the ${\Lambda }_c^{+}{\Lambda }_c^{-}$ invariant mass distribution just above threshold. With an assumption of a resonance origin for the observed peak, a mass and width of $M=[{4634}_{-7}^{+8}(\mathrm{stat}{)}_{-8}^{+5}(\mathrm{syst})]\mathrm{MeV}/c^2$ and ${\Gamma }_{\mathrm{tot}}=[{92}_{-24}^{+40}(\mathrm{stat}{)}_{-21}^{+10}(\mathrm{syst})]\mathrm{MeV}$ are determined. The analysis is based on a study of events with initial-state-radiation photons in a data sample collected with the Belle detector at the ${\rm Y}(4S)$ resonance and nearby continuum with an integrated luminosity of $695{\mathrm{fb}}^{-1}$ at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider.

We report the first observation of two resonancelike structures in the ${\pi }^{+}{\chi }_{c1}$ invariant mass distribution near $4.1\mathrm{GeV}/c^2$ in exclusive ${\overline{B}}^0\to K^{-}{\pi }^{+}{\chi }_{c1}$ decays. From a Dalitz plot analysis in which the ${\pi }^{+}{\chi }_{c1}$ mass structures are represented by Breit-Wigner resonance amplitudes, we determine masses and widths of: $M_1=(4051\pm {14}_{-41}^{+20})\mathrm{MeV}/c^2$, ${\Gamma }_1=({82}_{-17-22}^{+21+47})\mathrm{MeV}$, $M_2=({4248}_{-29-35}^{+44+180})\mathrm{MeV}/c^2$, and ${\Gamma }_2=({177}_{-39-61}^{+54+316})\mathrm{MeV}$; and product branching fractions of $\mathcal{B}({\overline{B}}^0\to K^{-}{Z}_{1,2}^{+})\times \mathcal{B}(Z_{1,2}^{+}\to {\pi }^{+}{\chi }_{c1})=({3.0}_{-0.8-1.6}^{+1.5+3.7})\times {10}^{-5}$ and $({4.0}_{-0.9-0.5}^{+2.3+19.7})\times {10}^{-5}$, respectively. Here the first uncertainty is statistical, the second is systematic. The significance of each of the ${\pi }^{+}{\chi }_{c1}$ structures exceeds $5\sigma$, including the systematic uncertainty from various fit models. This analysis is based on $657\times {10}^6$ $B\overline{B}$ events collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider.