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First measurement of proton-induced low-momentum dielectron radiation off cold nuclear matter
pl
dc.type
JournalArticle
pl
dc.description.physical
304-309
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dc.abstract.en
We present data on dielectron emission in proton induced reactions on a Nb target at 3.5 GeV kinetic beam energy measured with HADES installed at GSI. The data represent the first high statistics measurement of proton-induced dielectron radiation from cold nuclear matter in a kinematic regime, where strong medium effects are expected. Combined with the good mass resolution of 2%, it is the first measurement sensitive to changes of the spectral functions of vector mesons, as predicted by models for hadrons at rest or small relative momenta. Comparing the $e^{+} e^{−}$ invariant mass spectra to elementary p + p data, we observe for $e^{+} e^{−}$ momenta $P_{ee}$ < 0.8 GeV / c a strong modification of the shape of the spectrum, which we attribute to an additional $\rho$-like contribution and a decrease of $\omega$ yield. These opposite trends are tentatively interpreted as a strong coupling of the $\rho$ meson to baryonic resonances and an absorption of the $\omega$ meson, which are two aspects of in-medium modification of vector mesons.
pl
dc.description.volume
715
pl
dc.description.number
4-5
pl
dc.description.publication
0,3
pl
dc.identifier.doi
10.1016/j.physletb.2012.08.004
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dc.identifier.eissn
1873-2445
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dc.title.journal
Physics Letters. B
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dc.language.container
eng
pl
dc.affiliation
Wydział Fizyki, Astronomii i Informatyki Stosowanej : Instytut Fizyki im. Mariana Smoluchowskiego
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dc.subtype
Article
pl
dc.rights.original
CC-BY; otwarte czasopismo; ostateczna wersja wydawcy; w momencie opublikowania; 0;