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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
AU - Muon g-2
AU - Abi, B.
AU - Albahri, T.
AU - Al-Kilani, S.
AU - Allspach, D.
AU - Alonzi, L. P.
AU - Anastasi, A.
AU - Anisenkov, A.
AU - Azfar, F.
AU - Badgley, K.
AU - Baeßler, S.
AU - Bailey, I.
AU - Baranov, V. A.
AU - Barlas-Yucel, E.
AU - Barrett, T.
AU - Barzi, E.
AU - Basti, A.
AU - Bedeschi, F.
AU - Behnke, A.
AU - Berz, M.
AU - Bhattacharya, M.
AU - Binney, H. P.
AU - Bjorkquist, R.
AU - Bloom, P.
AU - Bono, J.
AU - Bottalico, E.
AU - Bowcock, T.
AU - Boyden, D.
AU - Cantatore, G.
AU - Carey, R. M.
AU - Carroll, J.
AU - Casey, B. C. K.
AU - Cauz, D.
AU - Ceravolo, S.
AU - Chakraborty, R.
AU - Chang, S. P.
AU - Chapelain, A.
AU - Chappa, S.
AU - Charity, S.
AU - Chislett, R.
AU - Choi, J.
AU - Chu, Z.
AU - Chupp, T. E.
AU - Convery, M. E.
AU - Conway, A.
AU - Corradi, G.
AU - Corrodi, S.
AU - Cotrozzi, L.
AU - Crnkovic, J. D.
AU - Korostelev, M.
AU - Valetov, E.
PY - 2021/4/7
Y1 - 2021/4/7
N2 - We present the first results of the Fermilab 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 ${\tilde{\omega}'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $\omega_a / {\tilde{\omega}'^{}_p}$, together with known fundamental constants, determines $a_\mu({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (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 $a_\mu({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviations
AB - We present the first results of the Fermilab 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 ${\tilde{\omega}'^{}_p}$ in a spherical water sample at 34.7$^{\circ}$C. The ratio $\omega_a / {\tilde{\omega}'^{}_p}$, together with known fundamental constants, determines $a_\mu({\rm FNAL}) = 116\,592\,040(54)\times 10^{-11}$ (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 $a_\mu({\rm Exp}) = 116\,592\,061(41)\times 10^{-11}$ (0.35\,ppm) increases the tension between experiment and theory to 4.2 standard deviations
KW - hep-ex
KW - nucl-ex
U2 - 10.1103/PhysRevLett.126.141801
DO - 10.1103/PhysRevLett.126.141801
M3 - Journal article
VL - 126
JO - Physical review letters
JF - Physical review letters
SN - 1079-7114
IS - 14
M1 - 141801
ER -