Search results for "generalized parton distribution"
showing 10 items of 12 documents
Prospects for quarkonium studies at the high-luminosity LHC
2020
Prospects for quarkonium-production studies accessible during the upcoming high-luminosity phases of the CERN Large Hadron Collider operation after 2021 are reviewed. Current experimental and theoretical open issues in the field are assessed together with the potential for future studies in quarkonium-related physics. This will be possible through the exploitation of the huge data samples to be collected in proton-proton, proton-nucleus and nucleus-nucleus collisions, both in the collider and fixed-target modes. Such investigations include, among others, those of: (i) J/psi and Upsilon produced in association with other hard particles; (ii) chi(c,b) and eta(c,b) down to small transverse mom…
Mesure de la section efficace de l'électroproduction de photons à JLAB dans le but d'effectuer une Séparation Rosenbluth de la contribution DVCS
2014
The study of the inner structure of hadrons allows us to understand the nature of the interactions between partons, quarks and gluons, described by Quantum Chromodynamics. The elastic scattering reactions, which have been studied in order to measure the nucleon form factors, are included in this frame. The inelastic scattering reactions are also included in this frame, they allow us to obtain information about the nucleon structure thanks to the development of the parton distribution functions (PDFs). While through elastic scattering we can obtain information about the charge distribution of the nucleon, and hence, about the spatial distribution of the partons, through inelastic scattering …
Poopćene raspodjele partona i struktura sastavnog kvarka
2003
In a scenario where the constituent quarks are composite systems, generalized parton distributions (GPDs) are built from wave functions to be evaluated in a constituent quark model (CQM), convoluted with the GPDs of the constituent quarks themselves. The approach permits to access the full kinematical range corresponding to the DGLAP and ERBL regions, so that cross-sections for deeply virtual Compton scattering can be estimated.
Measurement of azimuthal asymmetries associated with deeply virtual Compton scattering on a longitudinally polarized deuterium target
2010
Azimuthal asymmetries in exclusive electroproduction of a real photon from a longitudinally polarized deuterium target are measured with respect to target polarization alone and with respect to target polarization combined with beam helicity and/or beam charge. The asymmetries appear in the distribution of the real photons in the azimuthal angle $\phi$ around the virtual photon direction, relative to the lepton scattering plane. The asymmetries arise from the deeply virtual Compton scattering process and its interference with the Bethe-Heitler process. The results for the beam-charge and beam-helicity asymmetries from a tensor polarized deuterium target with vanishing vector polarization ar…
Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering
2009
The nuclear-mass dependence of azimuthal cross section asymmetries with respect to charge and longitudinal polarization of the lepton beam is studiedfor hard exclusive electroproduction of real photons. The observed beam-charge and beam-helicity asymmetries are attributed to the interference between the Bethe-Heitler and deeply virtual Compton scattering processes. For various nuclei, the asymmetries are extracted for both coherent and incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. For both regions, the asymmetries are compared to those for a free proton, and no nuclear-mass dependence is found.
Pion-photon transition distribution amplitudes in the Nambu-Jona-Lasinio model
2007
12 pages, 6 figures.-- PACS nrs.: 13.60.-r; 11.10.St; 12.38.Lg; 24.10.Jv.-- ISI Article Identifier: 000251327200049.-- ArXiv pre-print available at: http://arxiv.org/abs/0707.3366
Dispersive evaluation of the D-term form factor in deeply virtual Compton scattering
2014
We present a dispersive representation of the D-term form factor for hard exclusive reactions, using unsubtracted $t$-channel dispersion relations. The $t$-channel unitarity relation is saturated with the contribution of two-pion intermediate states, using the two-pion distributions amplitude for the $\gamma^*\gamma\rightarrow \pi\pi$ subprocess and reconstructing the $\pi\pi\rightarrow N\bar N$ subprocess from available information on pion-nucleon partial-wave helicity amplitudes. Results for the D-term form factor as function of $t$ as well as at $t=0$ are discussed in comparison with available model predictions and phenomenological parametrizations.
Rosenbluth Separation of the π^{0} Electroproduction Cross Section.
2016
We present deeply virtual $\pi^0$ electroproduction cross-section measurements at $x_B$=0.36 and three different $Q^2$--values ranging from 1.5 to 2 GeV$^2$, obtained from experiment E07-007 that ran in the Hall A at Jefferson Lab. The Rosenbluth technique was used to separate the longitudinal and transverse responses. Results demonstrate that the cross section is dominated by its transverse component, and thus is far from the asymptotic limit predicted by perturbative Quantum Chromodynamics. An indication of a non-zero longitudinal contribution is provided by the interference term $\sigma_{LT}$ also measured. Results are compared with several models based on the leading twist approach of G…
Transverse extension of partons in the proton probed in the sea-quark range by measuring the DVCS cross section
2019
Physics letters / B B793, 188-194 (2019). doi:10.1016/j.physletb.2019.04.038
Measurement of the cross section for hard exclusive π0 muoproduction on the proton
2020
Physics letters / B B805, 135454 (2020). doi:10.1016/j.physletb.2020.135454