A. Mussgiller
A5057658039- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Cosmology and Gravitation Theories
- Neutrino Physics Research
- Medical Imaging Techniques and Applications
- Astrophysics and Cosmic Phenomena
- Nuclear physics research studies
- Particle Accelerators and Free-Electron Lasers
- Black Holes and Theoretical Physics
- Radiation Detection and Scintillator Technologies
- Distributed and Parallel Computing Systems
- Atomic and Subatomic Physics Research
- Nuclear Physics and Applications
- Scientific Computing and Data Management
- Atomic and Molecular Physics
- Nuclear reactor physics and engineering
- Gamma-ray bursts and supernovae
- Crystallography and Radiation Phenomena
- Noncommutative and Quantum Gravity Theories
- Radiation Therapy and Dosimetry
- Statistical Methods and Bayesian Inference
Deutsches Elektronen-Synchrotron DESY
2016-2025
Institute of High Energy Physics
2022-2024
European Organization for Nuclear Research
2012-2024
University of Antwerp
2023-2024
A. Alikhanyan National Laboratory
2022-2024
Vrije Universiteit Brussel
2023
Friedrich-Alexander-Universität Erlangen-Nürnberg
2007-2019
Argonne National Laboratory
2013
Joint Institute for Nuclear Research
2007-2010
Peking University
2007-2010
Azimuthal single-spin asymmetries of lepto-produced pions and charged kaons were measured on a transversely polarized hydrogen target. Evidence for naive-T-odd, transverse-momentum-dependent parton distribution function is deduced from non-vanishing Sivers effects pi+, pi0, K+, K-, as well in the difference pi+ pi- cross sections.
Single-spin asymmetries for pions and charged kaons are measured in semi-inclusive deep-inelastic scattering of positrons electrons off a transversely nuclear-polarized hydrogen target. The dependence the cross section on azimuthal angles target polarization (phi_S)and produced hadron (phi) is found to have substantial sin(phi+phi_S) modulation production pi+, pi- K+. This Fourier component can be interpreted terms non-zero transversity distribution functions favored disfavored Collins...
Beam-helicity and beam-charge asymmetries in the hard exclusive leptoproduction of real photons from an unpolarised hydrogen target by a 27.6 GeV lepton beam are extracted HERMES data set 2006-2007 using missing-mass event selection technique. The asymmetry amplitudes this more precise than those earlier 1996-2005 previously analysed same manner HERMES. results two sets compatible with each other. Results these combined constitute most amplitude measurements made kinematic region
A bstract The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized Hera positron beam scattering off an unpolarized hydrogen target is measured at Hermes. arises from deeply virtual Compton and its interference with Bethe-Heitler process. Azimuthal amplitudes are extracted a data sample consisting ep → epγ events detection all particles final state including recoiling proton. installation recoil detector, while reducing acceptance experiment,...
Double-spin asymmetries in exclusive electroproduction of real photons from a transversely polarized hydrogen target are measured with respect to the product polarization beam helicity and charge, alone. The arise deeply virtual Compton scattering process its interference Bethe--Heitler process. They related part same combination form factors as that determining previously published transverse single-spin through imaginary part. results for double-spin found be compatible zero within...
Longitudinal double-spin asymmetries of charged hadrons with high transverse momentum p T have been measured in electroproduction using the Hermes detector at Hera. Processes involving gluons nucleon enhanced relative to others by selecting typically above 1 GeV. In this kinematic domain gluon polarization has extracted leading order making use model embedded Monte Carlo Generator Pythia 6.2. The obtained from single inclusive range GeV < 2.5 a deuterium target is $ \frac{{\Delta...
An earlier extraction from the HERMES experiment of polarization-averaged parton distribution strange quarks in nucleon has been reevaluated using final data on multiplicities charged kaons semi-inclusive deep-inelastic scattering obtained with a kinematically more comprehensive method correcting for experimental effects. General features are confirmed, but rise at low x is less pronounced than previously reported.
The pp->pp phi reaction has been studied at the Cooler Synchrotron COSY-Juelich, using internal beam and ANKE facility. Total cross sections have determined three excess energies epsilon near production threshold. differential section closest to threshold epsilon=18.5 MeV exhibits a clear S-wave dominance as well noticeable effect due proton-proton final state interaction. Taken together with data for pp omega-production, significant enhancement of phi/omega ratio factor 8 is found compared...
The exclusive electroproduction of π+ mesons was studied with the HERMES spectrometer at DESY laboratory by scattering 27.6 GeV positron and electron beams off an internal hydrogen gas target. virtual-photon cross sections were measured as a function Mandelstam variable t squared four momentum −Q2 exchanged virtual photon. A model calculation based on Generalized Parton Distributions is in fair agreement data low values |t| if power corrections are included. Regge formalism gives good...
The differential and total cross sections for kaon pair production in the pp->ppK+K- reaction have been measured at three beam energies of 2.65, 2.70, 2.83 GeV using ANKE magnetic spectrometer COSY-Juelich accelerator. These near-threshold data are separated into pairs arising from decay phi-meson remainder. For non-phi selection, ratio terms K-p K+p invariant masses is strongly peaked towards low masses. This effect can be described quantitatively by a simple ansatz final state...
Exclusive electroproduction of pi+ mesons was studied by scattering 27.6 GeV positrons or electrons off a transversely polarized hydrogen target. The single-spin azimuthal asymmetry with respect to target polarization measured as function the Mandelstam variable t, Bjorken scaling x_B, and virtuality Q^2 exchanged photon. extracted Fourier components were found be consistent zero, except one that large involves interference contributions from longitudinal transverse virtual photons.
Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the Hermes experiment. The studied as a function azimuthal angle ψ about beam direction between target-spin hadron production plane, transverse momentum PT relative to incident beam, Feynman variable xF. sin amplitudes are positive for π+ K+, slightly negative π− consistent with zero K−, particular but weak xF dependences. Especially large observed two...
A measurement of the virtual-photon asymmetry A_2(x,Q^2) and spin-structure function g_2(x,Q^2) proton are presented for kinematic range 0.004 < x 0.9 0.18 GeV^2 Q^2 20 GeV^2. The data were collected by HERMES experiment at HERA storage ring DESY while studying inclusive deep-inelastic scattering 27.6 GeV longitudinally polarized leptons off a transversely hydrogen gas target. results consistent with previous experimental from CERN SLAC. For x-range covered, measured integral g_2(x)...
The nuclear--mass dependence of azimuthal cross-section asymmetries with respect to charge and longitudinal polarization the lepton beam is studied for hard exclusive electroproduction real photons. observed beam-charge beam-helicity are attributed interference between Bethe-Heitler deeply virtual Compton scattering processes. For various nuclei, extracted both coherent incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. compared those a...
The transverse-target single-spin asymmetry for inclusive deep-inelastic scattering with effectively unpolarized electron and positron beams off a transversely polarized hydrogen target was measured, the goal of searching two-photon exchange signal in kinematic range 0.007<xB<0.9 0.25GeV2<Q2<20GeV2. In two separate regions Q2>1GeV2 Q2<1GeV2, both beams, asymmetries are found to be consistent zero within statistical systematic uncertainties, which order 10−3 integrated over xB.
Results of inclusive measurements inelastic electron and positron scattering from unpolarized protons deuterons at the HERMES experiment are presented. The structure functions F 2 p d determined using a parameterization existing data for longitudinal-to-transverse virtual-photon absorption cross-section ratio. results provide in ranges 0.006 ≤ x 0.9 0.1 GeV2 Q 20 GeV2, covering transition region between perturbative non-perturbative regimes QCD so-far largely unexplored kinematic region....
The quasifree $pn\ensuremath{\rightarrow}d\ensuremath{\phi}$ reaction has been studied at the Cooler Synchrotron COSY---J\"ulich, using internal proton beam incident on a deuterium cluster-jet target and detecting fast deuteron in coincidence with ${K}^{+}{K}^{\ensuremath{-}}$ decay of $\ensuremath{\phi}$ meson. energy dependence total differential cross sections are extracted for excess energies up to 80 MeV by determining Fermi momentum neutron an event-by-event basis. Though these...
The exclusive electroproduction of ρ0 mesons was studied with the hermes spectrometer at Desy laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. Spin density matrix elements for this process were determined from measured production- decay-angle distributions produced mesons. These embody information on helicity transfer validity s-channel conservation in case From spin elements, leading-twist term single-spin asymmetry calculated...
The vector and tensor polarizations of a deuteron beam have been measured using elastic deuteron-carbon scattering at 75.6 MeV deuteron-proton 270 MeV. After acceleration to 1170 inside the COSY ring, deuterons were checked by studying variety nuclear reactions cluster target ANKE magnet spectrometer placed an internal position storage ring. All these measurements consistent with absence depolarization during provide number secondary standards that can be used in subsequent experiments facility.