Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

G. Agakishiev; H. Alvarez-Pol; A. Balanda; R. Bassini; M. Böhmer; H. Bokemeyer; J. L. Boyard; P. Cabanelas; S. Chernenko; T. Christ; M. Destefanis; F. Dohrmann; A. Dybczak; T. Eberl; L. Fabbietti; O. Fateev; P. Finocchiaro; J. Friese; I. Fröhlich; T. Galatyuk; J. A. Garzón; R. Gernhäuser; C. Gilardi; M. Golubeva; D. González-Dıaz; F. Guber; M. Gumberidze; T. Hennino; R. Holzmann; A. Ierusalimov; I. Iori; A. Ivashkin; M. Jurkovic; B. Kämpfer; K. Kanaki; T. Karavicheva; I. Koenig; W. Koenig; B. W. Kolb; R. Kotte; A. Kozuch; F. Krizek; W. Kühn; A. Kugler; A. Kurepin; S. Lang; K. Lapidus; T. Liu; L. Maier; J. Markert; V. Metag; B. Michalska; E. Morinière; J. Mousa; M. Münch; C. Müntz; L. Naumann; J. Otwinowski; Y. C. Pachmayer; V. Pechenov; O. Pechenova; T. Pérez Cavalcanti; J. Pietraszko; V. Pospısil; W. Przygoda; B. Ramstein; A. Reshetin; M. Roy-Stephan; A. Rustamov; A. Sadovsky; B. Sailer; P. Salabura; M. Sánchez; A. Schmah; E. Schwab; Yu. G. Sobolev; S. Spataro; B. Spruck; H. Ströbele; J. Stroth; C. Sturm; A. Tarantola; K. Teilab; P. Tlusty; A. Toia; M. Traxler; R. Trebacz; H. Tsertos; V. Wagner; M. Wisniowski; T. Wojcik; J. Wüstenfeld; S. Yurevich; Y. Zanevsky; P. Zumbruch

doi:10.1140/epja/i2012-12074-9

2023 Impact factor 2.6

Hadrons and Nuclei

Open Access

Eur. Phys. J. A (2012) 48: 74
https://doi.org/10.1140/epja/i2012-12074-9

Regular Article - Experimental Physics

Study of exclusive one-pion and one-eta production using hadron and dielectron channels in pp reactions at kinetic beam energies of 1.25 GeV and 2.2 GeV with HADES

HADES Collaboration
G. Agakishiev⁵, H. Alvarez-Pol¹⁵, A. Balanda², R. Bassini¹⁰, M. Böhmer⁸, H. Bokemeyer³, J. L. Boyard¹³, P. Cabanelas¹⁵, S. Chernenko⁵, T. Christ⁸, M. Destefanis⁹, F. Dohrmann⁴, A. Dybczak², T. Eberl⁸, L. Fabbietti⁷, O. Fateev⁵, P. Finocchiaro¹, J. Friese⁸, I. Fröhlich⁶, T. Galatyuk⁶, J. A. Garzón¹⁵, R. Gernhäuser⁸, C. Gilardi⁹, M. Golubeva¹¹, D. González-Dıaz¹, F. Guber¹¹, M. Gumberidze¹³, T. Hennino¹³, R. Holzmann³, A. Ierusalimov⁵, I. Iori¹⁰, A. Ivashkin¹¹, M. Jurkovic⁸, B. Kämpfer⁴, K. Kanaki⁴, T. Karavicheva¹¹, I. Koenig³, W. Koenig³, B. W. Kolb³, R. Kotte⁴, A. Kozuch², F. Krizek¹⁴, W. Kühn⁹, A. Kugler¹⁴, A. Kurepin¹¹, S. Lang³, K. Lapidus⁷, T. Liu¹³, L. Maier⁸, J. Markert⁶, V. Metag⁹, B. Michalska², E. Morinière¹³, J. Mousa¹², M. Münch³, C. Müntz⁶, L. Naumann⁴, J. Otwinowski², Y. C. Pachmayer⁶, V. Pechenov³, O. Pechenova⁶, T. Pérez Cavalcanti⁹, J. Pietraszko⁶, V. Pospısil¹⁴, W. Przygoda², B. Ramstein¹³, A. Reshetin¹¹, M. Roy-Stephan¹³, A. Rustamov³, A. Sadovsky¹¹, B. Sailer⁸, P. Salabura², M. Sánchez¹⁵, A. Schmah¹, E. Schwab³, Yu. G. Sobolev¹⁴, S. Spataro¹^,9, B. Spruck⁹, H. Ströbele⁶, J. Stroth³^,6, C. Sturm³, A. Tarantola⁶, K. Teilab⁶, P. Tlusty¹⁴, A. Toia⁹, M. Traxler³, R. Trebacz², H. Tsertos¹², V. Wagner¹⁴, M. Wisniowski², T. Wojcik², J. Wüstenfeld⁴, S. Yurevich³, Y. Zanevsky⁵ and P. Zumbruch³

¹ Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, 95125, Catania, Italy
² Smoluchowski Institute of Physics, Jagiellonian University of Cracow, 30-059, Kraków, Poland
³ GSI Helmholtz-Zentrum für Schwerionenforschung GmbH, 64291, Darmstadt, Germany
⁴ Institut für Strahlenphysik, Helmholtz-Zentrum Dresden-Rossendorf, 01314, Dresden, Germany
⁵ Joint Institute of Nuclear Research, 141980, Dubna, Russia
⁶ Institut für Kernphysik, Goethe-Universität, 60438, Frankfurt, Germany
⁷ Excellence Cluster “Origin and Structure of the Universe”, 85748, Garching, Germany
⁸ Physik Department E12, Technische Universität München, 85748, Garching, Germany
⁹ II.Physikalisches Institut, Justus Liebig Universität Giessen, 35392, Giessen, Germany
¹⁰ Istituto Nazionale di Fisica Nucleare, Sezione di Milano, 20133, Milano, Italy
¹¹ Institute for Nuclear Research, Russian Academy of Science, 117312, Moscow, Russia
¹² Department of Physics, University of Cyprus, 1678, Nicosia, Cyprus
¹³ Institut de Physique Nucléaire (UMR 8608), CNRS/IN2P3 - Université Paris Sud, F-91406, Orsay Cedex, France
¹⁴ Nuclear Physics Institute, Academy of Sciences of Czech Republic, 25068, Rez, Czech Republic
¹⁵ Departamento de Fısica de Partıculas, Univ. de Santiago de Compostela, 15706, Santiago de Compostela, Spain

Received: 6 March 2012
Accepted: 16 April 2012
Published online: 29 May 2012

Abstract

We present measurements of exclusive $\ensuremath \pi^{+,0}$ and $\eta$ production in pp reactions at 1.25GeV and 2.2GeV beam kinetic energy in hadron and dielectron channels. In the case of $\pi^{+}_{}$ and $\pi^{0}_{}$ , high-statistics invariant-mass and angular distributions are obtained within the HADES acceptance as well as acceptance-corrected distributions, which are compared to a resonance model. The sensitivity of the data to the yield and production angular distribution of $\Delta$ (1232) and higher-lying baryon resonances is shown, and an improved parameterization is proposed. The extracted cross-sections are of special interest in the case of pp $\rightarrow$ pp $\eta$ , since controversial data exist at 2.0GeV; we find $\ensuremath \sigma=0.142\pm0.022$ mb. Using the dielectron channels, the $\pi^{0}_{}$ and $\eta$ Dalitz decay signals are reconstructed with yields fully consistent with the hadronic channels. The electron invariant masses and acceptance-corrected helicity angle distributions are found in good agreement with model predictions.