A5034773199- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Nuclear physics research studies
- Atomic and Molecular Physics
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Nuclear Physics and Applications
- Computational Physics and Python Applications
- Advanced NMR Techniques and Applications
- Black Holes and Theoretical Physics
- Medical Imaging Techniques and Applications
- Advanced Chemical Physics Studies
- Physics of Superconductivity and Magnetism
- Radiation Detection and Scintillator Technologies
- Particle accelerators and beam dynamics
- Quantum, superfluid, helium dynamics
- Cosmology and Gravitation Theories
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced X-ray Imaging Techniques
- Cold Atom Physics and Bose-Einstein Condensates
- Muon and positron interactions and applications
- Particle Detector Development and Performance
Johannes Gutenberg University Mainz
2015-2024
Duke University
2022
Triangle Universities Nuclear Laboratory
2022
Novosibirsk State University
2020
Budker Institute of Nuclear Physics
2020
Deutsches Elektronen-Synchrotron DESY
2019
Helmholtz Institute Mainz
2011-2018
Williams (United States)
2004-2017
William & Mary
2004-2017
Moscow Engineering Physics Institute
2017
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...
The proton is responsible for about half the mass in our personal lives. So it perhaps surprising that little known how got here or bound from its fundamental quark and gluon constituents. This uncertainty largest source of error to extracting some constants nature. One observable probes internal structure tests theoretical description charge radius. radius sensitive quantum electrodynamics chromodynamics helps constrain new physics. review presents current status among four types...
A dispersive implementation of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msub><a:mi>a</a:mi><a:mn>0</a:mn></a:msub><a:mo stretchy="false">(</a:mo><a:mn>980</a:mn><a:mo stretchy="false">)</a:mo></a:math> resonance to <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mo stretchy="false">(</e:mo><e:mi>g</e:mi><e:mo>−</e:mo><e:mn>2</e:mn><e:msub><e:mo stretchy="false">)</e:mo><e:mi>μ</e:mi></e:msub></e:math> requires knowledge...
The apparent discrepancy between the Rosenbluth and polarization transfer methods for ratio of electric to magnetic proton form factors can be explained by a two-photon exchange correction which does not destroy linearity plot. Though intrinsically small, order few percent cross section, this is accidentally amplified in case method.
We estimate the leading order amplitudes for exclusive photon and meson electroproduction reactions at large ${Q}^{2}$ in valence region terms of skewed quark distributions. As experimental investigations can currently only be envisaged moderate values ${Q}^{2},$ we power corrections due to intrinsic transverse momentum partons wave function nucleon. To this aim, parton distribution formalism is generalized so as include dependence. Furthermore, reactions, calculate soft overlap type...
We discuss the links between Generalized Parton Distributions (GPDs) and elastic nucleon form factors. These links, in of sum rules, represent powerful constraints on parametrizations GPDs. A Regge parametrization for GPDs at small momentum transfer, is extended to large transfer region it found describe basic features proton neutron electromagnetic factor data. This used estimate quark contribution spin.
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer through off a parton in proton. relate amplitude generalized distributions which appear hard exclusive processes. find that when taking polarization determinations of form factors as input, adding 2-photon correction does reproduce Rosenbluth cross sections.
This work reviews the recent developments in field of Generalized Parton Distributions (GPDs) and Deeply virtual Compton scattering valence region, which aim at extracting quark structure nucleon. We discuss constraints present generation measurements provide on GPDs, examine several state-of-the-art parametrizations GPDs. Future directions this active are discussed.
We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. thus can relate amplitude generalized parton distributions which also enter in other wide-angle processes. find that interference one- and is able substantially resolve difference between electric form factor measurements from Rosenbluth polarization experiments. Two-photon has additional consequences could be...
We develop the formalism to provide an improved estimate for hadronic light-by-light correction muon's anomalous magnetic moment a_{\mu}, by considering single meson contributions beyond leading pseudo-scalar mesons. incorporate available experimental input as well constraints from scattering sum rules effects of axial-vector, scalar, and tensor give numerical evaluations contribution these states a_{\mu}. The presented allows further improve on estimates, once new data such will become available.
We evaluate the light-quark meson contributions to three exact light-by-light scattering sum rules in light of new data by Belle Collaboration, which recently has extracted transition form factors tensor ${f}_{2}(1270)$ as well scalar ${f}_{0}(980)$. confirm a previous finding that $\ensuremath{\eta},{\ensuremath{\eta}}^{\ensuremath{'}}$ and helicity-2 saturate one these up photon virtualities around $1\text{ }\text{ }\mathrm{Ge}{\mathrm{V}}^{2}$. At larger virtualities, our rule analysis...
The recent conundrum with the proton charge radius inspires reconsideration of corrections that enter into determinations size. We study two-photon proton-structure corrections, special consideration non-pole subtraction term in dispersion relation, and using fits to modern data evaluate energy contributions. find individual contributions change more than total, present results error estimates.
We present a new general dispersive formalism for evaluating the hadronic light-by-light scattering contribution to anomalous magnetic moment of muon. In suggested approach, this correction is related imaginary part muon's electromagnetic vertex function. The latter may be directly measurable processes by means unitarity and analyticity. As test we apply introduced case meson pole exchanges find agreement with direct two-loop calculation.
The $\ensuremath{\gamma}$, ${\ensuremath{\pi}}^{0}$, and ${\ensuremath{\rho}}_{L}^{0}$ electroproduction reactions are studied in the Bjorken regime. They sensitive to recently introduced off-forward parton distributions. A factorized model for these distributions is shown be able interpret few existing data. Calculations given different kinematics experimental perspectives discussed.
Two-photon exchange contributions to elastic electron-scattering are reviewed. The apparent discrepancy in the extraction of nucleon form factors between unpolarized Rosenbluth and polarization transfer experiments is discussed, as well understanding this puzzle terms two-photon corrections. Calculations such corrections both within partonic hadronic frameworks In view recent spin-dependent electron scattering data, relation process hyperfine splitting hydrogen critically examined. imaginary...
Using only the current empirical information on nucleon electromagnetic form factors we map out transverse charge density in proton and neutron as viewed from a light front moving towards transversely polarized nucleon. These densities are characterized by dipole pattern, addition to monopole field corresponding with unpolarized density. Furthermore, use latest N-->Delta transition which induces excitation. This N Delta contains both monopole, quadrupole patterns, latter deformation of distribution.
We present a dispersive representation of the D-term form factor for hard exclusive reactions, using unsubtracted t-channel dispersion relations. The unitarity relation is saturated with contribution two-pion intermediate states, distributions amplitude γ⁎γ→ππ subprocess and reconstructing ππ→NN¯ from available information on pion-nucleon partial-wave helicity amplitudes. Results as function t well at t=0 are discussed in comparison model predictions phenomenological parametrizations.
Abstract The Gamma Factory (GF) is an ambitious proposal, currently explored within the CERN Physics Beyond Colliders program, for a source of photons with energies up to ≈400 MeV and photon fluxes (up ≈10 17 s −1 ) exceeding those available gamma sources by orders magnitude. high‐energy (secondary) are produced via resonant scattering primary laser highly relativistic partially‐stripped ions circulating in accelerator. secondary emitted narrow cone energy beam can be monochromatized, down...