Event calendar file
Study of baryonic resonances and the $\rho$ meson production in the reaction $pp\to pp \pi^+ \pi^-$ at 3.5 GeV with HADES
Speakers
- Amel BELOUNNAS
Primary authors
- Amel BELOUNNAS (Institue de Physique Nucléaire Orsay (IPNO))
Co-authors
- Dr. Beatrice RAMSTEIN (Institut de Physique Nucleaire Orsay)
Files
Collaboration
HADES Collaboration
Abstract content
Pion production in $NN$ collisions is one of the sources of information on the $NN$ interaction and on the contribution of nucleon resonances. In particular, two-pion production in the few energy range, carries information both on $\pi\pi$ dynamics and on single and double baryon excitation.
The High Acceptance Di-Electron Spectrometer (HADES)[1] installed at GSI
Helmholtz-Zentrum für Schwerionenforschung in Darmstadt, designed to investigate dielectron production in heavy-ion collisions in the range of kinetic beam energies 1-2 A GeV is also an excellent detector for charged hadron detection, due to its tracking capabilities.
Recently, differential and integrated cross sections for the reactions $pp\to pp\pi^0$, $pp\to pn\pi^+$ [2-3-4], $pp\to pp\pi^+ \pi^-$, $pn\to pn\pi^+\pi^-$ [5], $pn\to d\pi^+\pi^-$ have been investigated with HADES at kinetic energies 1.25, 2.2 and 3.5 GeV. This talk will focus on the analysis of the $pp\to pp\pi^+\pi^-$ channel at 3.5 GeV, using results from $pp\to pp\pi^0$, $pp\to pn \pi^+$ [3] and
$pp\to pK \Lambda$ [6] measured at the same energy by HADES. The contributions of the excitation of one or two baryonic resonances with masses up to 1.9 GeV and of the ρ production can be quantified. The results are compared with two theoretical models [7-8].
The results of this study provide strong constraints on the pion production mechanisms and on the various resonance contributions $(\Delta(1232), N^\ast(1440),...)$, as well as on the double resonance excitation and the direct $\rho$ production. These aspects are closely related to the interpretation of the dielectron spectra measured by the HADES collaboration. Baryonic resonances are indeed important sources of dileptons through two mechanisms: the Dalitz decay (e.g. $R\to N e^+e^−$) and the mesonic decay with subsequent dielectron production.
[1] G. Agakishiev et al., Eur. Phys. J. A41, 243-277 (2009).
[2] G. Agakishiev et al. Eur.Phys.J. A48 (2012) 74.
[3] G. Agakishiev et al. Eur.Phys.J. A50 (2014) 82.
[4] G. Agakishiev et al. , Eur.Phys.J. A51 (2015), 137.
[5] G. Agakishiev et al., Phys.Lett. B750 (2015) 184.
[6] G. Agakishiev et al. Phys.Lett. B742 (2015) 242-248.
