A5042834972- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Computational Physics and Python Applications
University of Bern
2020-2022
University of Illinois Urbana-Champaign
2020
Fermi National Accelerator Laboratory
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...
A bstract While the low-energy part of hadronic light-by-light (HLbL) tensor can be constrained from data using dispersion relations, for a full evaluation its contribution to anomalous magnetic moment muon ( g − 2) μ also mixed- and high-energy regions need estimated. Both addressed within operator product expansion (OPE), either configurations where all photon virtualities become large or one them remains finite. Imposing such short-distance constraints (SDCs) on HLbL is thus major aspect...
A key ingredient in the evaluation of hadronic light-by-light (HLbL) scattering anomalous magnetic moment muon $(g-2)_\mu$ concerns short-distance constraints (SDCs) that follow from QCD by means operator product expansion. Here we concentrate on most important such constraint, longitudinal amplitudes, and show it can be implemented efficiently terms a Regge sum over excited pseudoscalar states, constrained phenomenological input masses, two-photon couplings, as well SDCs HLbL transition...
We reassess the impact of short-distance constraints for longitudinal component hadronic light-by-light amplitude on anomalous magnetic moment muon, $a_\mu=(g-2)_\mu/2$, by comparing different solutions that have recently appeared in literature. In particular, we analyze relevance exact axial anomaly and its $a_\mu$ conclude it remains rather limited. show all proposed agree well within uncertainties numerical estimate $a_\mu$, despite differences concrete implementation. also take into...
A bstract The hadronic light-by-light contribution to the muon anomalous magnetic moment depends on an integration over three off-shell momenta squared ( $$ {Q}_i^2 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mi>Q</mml:mi><mml:mi>i</mml:mi><mml:mn>2</mml:mn></mml:msubsup></mml:math> ) of correlator four electromagnetic currents and fourth leg at zero momentum. We derive short-distance expansion this in limit where all are large Euclidean domain QCD. This is...
A bstract The short-distance behaviour of the hadronic light-by-light (HLbL) contribution to ( g − 2) μ has recently been studied by means an operator product expansion in a background electromagnetic field. leading term this shown be given massless quark loop, and non-perturbative corrections are numerically very suppressed. Here, we calculate perturbative QCD correction loop. is found fairly small compared loop as far study energy scales where running for coupling well-defined, i.e. ≳ 1...
The current $3.7\sigma$ discrepancy between the Standard Model prediction and experimental value of muon anomalous magnetic moment could be a hint for existence new physics. hadronic light-by-light contribution is one pieces requiring improved precision on theory side, an important step to derive short-distance constraints this quantity containing four electromagnetic currents. Here, we such three large photon loop virtualities external fourth in static limit. considered as background field...
The recent experimental measurement of the muon g−2 at Fermilab National Laboratory, a 4.2σ tension with Standard Model prediction, highlights need for further improvements on theoretical uncertainties associated to hadronic sector. In framework operator product expansion in presence background feld, short-distance behaviour light-by-light contribution was recently studied. leading term this is given by massless quark-loop, which numerically dominant compared non-perturbative corrections....
The recent experimental measurement of the muon $g-2$ at Fermilab National Laboratory, a $4.2\sigma$ tension with Standard Model prediction, highlights need for further improvements on theoretical uncertainties associated to hadronic sector. In framework operator product expansion in presence background field, short-distance behaviour light-by-light contribution was recently studied. leading term this is given by massless quark-loop, which numerically dominant compared non-perturbative...