Alexander Keshavarzi
A5004879104- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Computational Physics and Python Applications
- Dark Matter and Cosmic Phenomena
- Muon and positron interactions and applications
- Neutrino Physics Research
- Particle Accelerators and Free-Electron Lasers
- Particle Detector Development and Performance
- Superconducting Materials and Applications
- Laser-induced spectroscopy and plasma
- Particle accelerators and beam dynamics
- Electron and X-Ray Spectroscopy Techniques
- Plasma Diagnostics and Applications
- Radiation Detection and Scintillator Technologies
- Black Holes and Theoretical Physics
- Nuclear Physics and Applications
- Scientific Computing and Data Management
- International Science and Diplomacy
- Distributed and Parallel Computing Systems
- Astrophysics and Cosmic Phenomena
- Scientific Research and Discoveries
University of Manchester
2020-2025
Manchester University
2020-2024
The University of Adelaide
2019-2020
York University
2019-2020
High Energy Accelerator Research Organization
2019-2020
Universitat Autònoma de Barcelona
2019-2020
University of Liverpool
2017-2020
University of Mississippi
2019-2020
San Francisco State University
2019-2020
Universidade de São Paulo
2020
We review the present status of Standard Model calculation anomalous magnetic moment muon. This is performed in a perturbative expansion fine-structure constant $\alpha$ and broken down into pure QED, electroweak, hadronic contributions. The QED contribution by far largest has been evaluated up to including $\mathcal{O}(\alpha^5)$ with negligible numerical uncertainty. electroweak suppressed $(m_\mu/M_W)^2$ only shows at level seventh significant digit. It two loops known better than one...
This work presents a complete reevaluation of the hadronic vacuum polarization contributions to anomalous magnetic moment muon, aμhad,VP, and effective QED coupling at mass Z boson, Δαhad(MZ2), from combination e+e−→hadrons cross section data. Focus has been placed on development new data method, which fully incorporates all correlated statistical systematic uncertainties in bias free approach. All available have analyzed included, where compilation yielded full R-ratio its covariance matrix...
Following updates in the compilation of $e^+e^-\rightarrow{\rm hadrons}$ data, this work presents re-evaluations hadronic vacuum polarisation contributions to anomalous magnetic moment electron ($a_e$), muon ($a_\mu$) and tau lepton ($a_\tau$), ground-state hyperfine splitting muonium also running QED coupling at mass scale $Z$ boson, $\alpha(M_Z^2)$. Combining results for with recent light-by-light corrections, electromagnetic weak contributions, deviation between measured value $a_\mu$ its...
We present a new measurement of the positive muon magnetic anomaly, a_{μ}≡(g_{μ}-2)/2, from Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. have analyzed more than 4 times number positrons decay our previous result 2018 data. The systematic error is reduced by factor 2 due to better running conditions, stable beam, improved knowledge field weighted distribution, ω[over ˜]_{p}^{'}, anomalous precession frequency corrected for beam dynamics effects, ω_{a}. From ratio...
The discrepancy between the Standard Model theory and experimental measurement of muon magnetic moment anomaly, ${a}_{\ensuremath{\mu}}=({g}_{\ensuremath{\mu}}\ensuremath{-}2)/2$, is connected to precision electroweak (EW) predictions via their common dependence on hadronic vacuum polarization effects. same data for total ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\text{hadrons}$ cross section, ${\ensuremath{\sigma}}_{\text{had}}(s)$, are used as input into dispersion relations...
The Muon g-2 Experiment at Fermi National Accelerator Laboratory (FNAL) has measured the muon anomalous precession frequency $ω_a$ 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 2018. When combined a precision measurement magnetic field experiment's ring, determines anomaly $a_μ({\rm FNAL}) = 116\,592\,040(54) \times 10^{-11}$ (0.46 ppm). This article describes...
In this paper, we discuss how windows in Euclidean time can be used to isolate the origin of potential conflicts between evaluations hadronic-vacuum-polarization (HVP) contribution anomalous magnetic moment muon lattice QCD and from $e^+e^-\to\text{hadrons}$ cross-section data. We provide phenomenological comparison numbers evaluated data for window quantities most commonly studied QCD, complete with correlations among them. evaluate modifications parameters that could useful dissecting...
The Fermi National Accelerator Laboratory has measured the anomalous precession frequency $a^{}_\mu = (g^{}_\mu-2)/2$ of muon to a combined precision 0.46 parts per million with data collected during its first physics run in 2018. This paper documents measurement magnetic field storage ring. is monitored by nuclear resonance systems and calibrated terms equivalent proton spin spherical water sample at 34.7$^\circ$C. weighted distribution resulting $\tilde{\omega}'^{}_p$, denominator ratio...
We present details on a new measurement of the muon magnetic anomaly, $a_\mu = (g_\mu -2)/2$. The result is based positive data taken at Fermilab's Muon Campus during 2019 and 2020 accelerator runs. uses $3.1$ GeV$/c$ polarized muons stored in $7.1$-m-radius storage ring with $1.45$ T uniform field. value $ a_{\mu}$ determined from measured difference between spin precession frequency its cyclotron frequency. This normalized to strength field, using Nuclear Magnetic Resonance (NMR). ratio...
A bstract The three precision measurements of the cross section σ ( e + − → π γ(γ)) using initial state radiation by KLOE collaboration provide an important input for prediction hadronic contribution to anomalous magnetic moment muon. These are correlated both statistical and systematic uncertainties and, therefore, simultaneous use these requires covariance matrices that fully describe correlations. We present construction them determine a combined measurement γ(γ)). find, from this...
The KNTW (Keshavarzi-Nomura-Teubner-Wright) data-driven determinations of the hadronic vacuum polarization (HVP) are crucial inputs to previous and future Standard Model (SM) predictions muon’s anomalous magnetic moment, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>a</a:mi><a:mi>μ</a:mi></a:msub></a:math>. With muon <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>g</c:mi><c:mo>−</c:mo><c:mn>2</c:mn></c:math>’s new physics...
We present a new measurement of the positive muon magnetic anomaly, $a_\mu \equiv (g_\mu - 2)/2$, from Fermilab Muon $g\!-\!2$ Experiment using data collected in 2019 and 2020. have analyzed more than 4 times number positrons decay our previous result 2018 data. The systematic error is reduced by factor 2 due to better running conditions, stable beam, improved knowledge field weighted distribution, $\tilde{\omega}'^{}_p$, anomalous precession frequency corrected for beam dynamics effects,...
A number of discrepancies have emerged between lattice computations and data-driven dispersive evaluations the RBC/UKQCD intermediate-window-hadronic contribution to muon anomalous magnetic moment. It is therefore interesting obtain estimates for light-quark-connected strange-plus-disconnected components this window quantity, allowing a more detailed comparison approaches. The aim paper provide these estimates, extending analysis several other quantities, including two windows designed focus...
The hadronic vacuum polarization (HVP) contributions to the muon g-2 are crucial quantity resolve whether new physics is present or not in comparison between standard model (SM) prediction and experimental measurements at Fermilab. They commonly historically determined via dispersion relations using a vast catalogue of experimentally measured, low-energy e^{+}e^{-}→hadrons cross section data as input. These dispersive estimates result SM that exhibits discrepancy more than 5σ when compared...
The electric dipole moments~(EDM) of fundamental particles inherently violate parity~(P) and time-reversal~(T) symmetries. By virtue the CPT theorem in quantum field theory, latter also implies violation combined charge-conjugation parity~(CP) symmetry. We aim to measure EDM muon using frozen-spin technique within a compact storage trap. This method exploits high effective field, \$E \approx 165\$ MV/m, experienced rest frame with momentum about 23 MeV/c when it passes through solenoidal...
A key issue affecting the attempt to reduce uncertainty on Standard Model prediction for muon anomalous magnetic moment is current discrepancy between lattice-QCD and data-driven results hadronic vacuum polarization. Progress this benefits from precise determinations of isospin-limit light-quark-connected (lqc) strange-plus-light-quark-disconnected (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi...
This letter of intent proposes an experiment to search for electric dipole moment the muon based on frozen-spin technique. We intend exploit high field, $E=1{\rm GV/m}$, experienced in rest frame with a momentum $p=125 {\rm MeV/}c$ when passing through large magnetic field $|\vec{B}|=3{\rm T}$. Current fluxes at $μ$E1 beam line permit improved sensitivity $σ(d_μ)\leq 6\times10^{-23}e{\rm cm}$, about three orders magnitude more than current upper limit $|d_μ|\leq1.8\times10^{-19}e{\rm...
We present the first data-driven result for ${a}_{\ensuremath{\mu}}^{\mathrm{win},\mathrm{lqc}}$, isospin-limit light-quark connected component of intermediate-window Hadronic-vacuum-polarization contribution to muon anomalous magnetic moment. Our result, $(198.8\ifmmode\pm\else\textpm\fi{}1.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$, is in significant tension with eight recent mutually compatible high-precision lattice-QCD determinations, and provides enhanced evidence a...
We use a new compilation of the hadronic $R$-ratio from available data for process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\text{hadrons}$ to determine strong coupling, ${\ensuremath{\alpha}}_{s}$. make all threshold center-of-mass energy 2 GeV by employing finite-energy sum rules. Data above GeV, which at present far fewer high-precision experimental are available, do not provide much additional constraint but fully consistent with values ${\ensuremath{\alpha}}_{s}$ we obtain....
The current ~ 3.5σ discrepancy between the experimental measurement and theoretical prediction of muon magnetic anomaly, a µ , stands as potential indication existence new physics. Muon g − 2 experiment at Fermilab is set to measure with four-fold improvement in uncertainty respect previous experiment, an aim determine whether well established. recently completed its first physics run summer programme essential upgrades, before continuing on programme. Run-1 data alone are expected yield...
We discuss the prospects for improving precision on hadronic corrections to anomalous magnetic moment of muon, and plans Muon $g-2$ Theory Initiative update Standard Model prediction.
The three precision measurements of the cross section $σ\big(e^+e^-\rightarrowπ^+π^-γ(γ)\big)$ using initial state radiation by KLOE collaboration provide an important input for prediction hadronic contribution to anomalous magnetic moment muon. These are correlated both statistical and systematic uncertainties and, therefore, simultaneous use these requires covariance matrices that fully describe correlations. We present construction them determine a combined measurement...
This paper presents the beam dynamics systematic corrections and their uncertainties for Run-1 data set of Fermilab Muon g-2 Experiment. Two to measured muon precession frequency $\omega_a^m$ are associated with well-known effects owing use electrostatic quadrupole (ESQ) vertical focusing in storage ring. An average vertically oriented motional magnetic field is felt by relativistic muons passing transversely through radial electric components created ESQ system. The correction depends on...