We present the inclusive di-electron invariant-mass spectrum from p+p interactions at 3.5 GeV kinetic beam energy. It is a very important reference for the study of vector meson production off the nucleus, recently investigated by HADES in p+93Nb reactions at the same beam energy. Up to invariant masses of 0.6 GeV/c2 the main contributions to the e+e− spectrum are 0, , and Dalitz decays. In the vector-meson region a clear peak corresponding to the direct decay is reconstructed with 2% mass resolution. Subtracting this peak from the spectrum allows to investigate additional sources, in particular the meson. Indeed, the latest results from HSD and UrQMD calculations show different distributions for the shape of the meson at these energies. Therefore it is important to experimentally understand the production mechanism of the meson in elementary reactions. Besides the spectral shape of the mesons, their inclusive production cross sections are also not known at these energies. Due to the large and flat acceptance of the HADES spectrometer for e+e− masses above 0.2 GeV/c2 and for PT<1GeV/c, acceptance corrections are to a large extent model independent. This allows us to extract the preliminary inclusive cross section values for the meson productions at these energies.

Inclusive meson production in 3.5-GeV p p collisions studied with the HADES spectrometer

SPATARO, STEFANO GIOVANNI;
2010-01-01

Abstract

We present the inclusive di-electron invariant-mass spectrum from p+p interactions at 3.5 GeV kinetic beam energy. It is a very important reference for the study of vector meson production off the nucleus, recently investigated by HADES in p+93Nb reactions at the same beam energy. Up to invariant masses of 0.6 GeV/c2 the main contributions to the e+e− spectrum are 0, , and Dalitz decays. In the vector-meson region a clear peak corresponding to the direct decay is reconstructed with 2% mass resolution. Subtracting this peak from the spectrum allows to investigate additional sources, in particular the meson. Indeed, the latest results from HSD and UrQMD calculations show different distributions for the shape of the meson at these energies. Therefore it is important to experimentally understand the production mechanism of the meson in elementary reactions. Besides the spectral shape of the mesons, their inclusive production cross sections are also not known at these energies. Due to the large and flat acceptance of the HADES spectrometer for e+e− masses above 0.2 GeV/c2 and for PT<1GeV/c, acceptance corrections are to a large extent model independent. This allows us to extract the preliminary inclusive cross section values for the meson productions at these energies.
2010
Hadron 2009: 13th International Conference On Hadron Spectroscopy
Tallahassee, Florida
29 Nov - 4 Dec 2009
1257
736
740
meson production; hadron mass; quantum chromodynamics; chiral symmetries; proton-proton interactions
Rustamov A; Spataro S; HADES Collaboration
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/81998
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