arXiv subjects

J. Garcia Llongo

Publications and source records attributed to J. Garcia Llongo.

3 recordsLinked to original sources

arXiv2011

Consistent threshold pi0 electro-production at Q^2=0.05, 0.10, and 0.15 GeV^2/c^2

New, accurate data are presented on the near threshold p(e,e'p)pi^0 reaction in the range of four-momentum transfers between Q^2=0.05 and 0.15GeV^2/c^2. The data were taken with the spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI. The complete center of mass solid angle was covered up to a center of mass energy of 4MeV above threshold. These results supersede the previous analysis based on three separate experiments, and are compared with calculations in Heavy Baryon Chiral Perturbation Theory and with phenomenological models.

nucl-ex↗

arXiv2007

Beam-helicity asymmetry in photon and pion electroproduction in the Delta(1232) resonance region at Q^2= 0.35 (GeV/c)^2

The beam-helicity asymmetry has been measured simultaneously for the reactions (e p \to e p γ) and (e p \to e p π^0) in the $Δ(1232)$ resonance region at $Q^2=$ 0.35 (GeV/c)$^2$. The experiment was performed at MAMI with a longitudinally polarized beam and an out-of-plane detection of the proton. The results are compared with calculations based on Dispersion Relations for virtual Compton scattering and with the MAID model for pion electroproduction. There is an overall good agreement between experiment and theoretical calculations. The remaining discrepancies may be ascribed to an imperfect parametrization of some $γ^{(*)} N \to πN$ multipoles, mainly contributing to the non-resonant background. The beam-helicity asymmetry in both channels ($γ$ and $π^0$) shows a good sensitivity to these multipoles and should allow future improvement in their parametrization.

hep-ph↗

arXiv2003

Search for Narrow Nucleon Resonances below Pion Threshold in the H(e,e'pi^+)X and D(e,e'p)X Reactions

In two series of high-resolution coincidence experiments at the three-spectrometer facility at MAMI, the H(e,e'pi^+)X and D(e,e'p)X reactions were studied to search for narrow nucleon resonances below pion threshold. The missing-mass resolution was 0.6 to 1.6 MeV/c^2 (FWHM) in the proton experiment and 0.9 to 1.3 MeV/c^2 in the deuteron experiment. The experiments covered the missing-mass region from the neutron mass up to about 1050 and 1100 MeV/c^2, respectively. None of our measurements showed a signal for narrow resonances to a level of down to 10^-4 with respect to the neutron peak in the missing-mass spectra.

nucl-ex↗