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## Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm

Research output: Contribution to Journal/MagazineJournal articlepeer-review

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In: Physical review letters, Vol. 126, No. 14, 141801, 07.04.2021.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

### Author

Muon g-2. / Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm. In: Physical review letters. 2021 ; Vol. 126, No. 14.

### Bibtex

@article{2956df08dfcd456b905967d0e9b92730,
title = "Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm",
abstract = " 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 ",
keywords = "hep-ex, nucl-ex",
author = "{Muon g-2} and B. Abi and T. Albahri and S. Al-Kilani and D. Allspach and Alonzi, {L. P.} and A. Anastasi and A. Anisenkov and F. Azfar and K. Badgley and S. Bae{\ss}ler and I. Bailey and Baranov, {V. A.} and E. Barlas-Yucel and T. Barrett and E. Barzi and A. Basti and F. Bedeschi and A. Behnke and M. Berz and M. Bhattacharya and Binney, {H. P.} and R. Bjorkquist and P. Bloom and J. Bono and E. Bottalico and T. Bowcock and D. Boyden and G. Cantatore and Carey, {R. M.} and J. Carroll and Casey, {B. C. K.} and D. Cauz and S. Ceravolo and R. Chakraborty and Chang, {S. P.} and A. Chapelain and S. Chappa and S. Charity and R. Chislett and J. Choi and Z. Chu and Chupp, {T. E.} and Convery, {M. E.} and A. Conway and G. Corradi and S. Corrodi and L. Cotrozzi and Crnkovic, {J. D.} and M. Korostelev and E. Valetov",
year = "2021",
month = apr,
day = "7",
doi = "10.1103/PhysRevLett.126.141801",
language = "English",
volume = "126",
journal = "Physical review letters",
issn = "1079-7114",
publisher = "American Physical Society",
number = "14",

}

### RIS

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 - 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 - 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 -