Contribution of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>and η Dalitz decays to the dilepton invariant-mass spectrum in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>1</mml:mn><mml:mi>A</mml:mi></mml:math>GeV heavy-ion collisions

Holzmann, R.; Appenheimer, M.; Averbeck, R.; Charbonnier, Y.; Delagrange, H.; Díaz, Julio Pérez; Döppenschmidt, A.; Hejny, V.; Hlaváč, S.; Куглер, А.; Lefèvre, F.; Löhner, H.; Marı́n, A.; Martı́nez, G.; Matulewicz, T.; Metag, V.; Novotny, R.; Ostendorf, R.W.; Pleskač, R.; Schutz, Y.; Siemssen, R.H.; Simon, R. S.; Ströher, H.; Tlustý, P.; Vogt, P.; Wagner, V.; Weiss, Jeffrey M.; Wilschut, Hans; Wissmann, F.; Wolf, A.; Wolf, M.

doi:10.1103/physrevc.56.r2920

Cited by 19 publications

(13 citation statements)

References 26 publications

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“…To do this check we simulated the pion and η contributions to the e + e − cocktail with the Pluto event generator [26,27] using the meson multiplicities and source parameters given in Table I. In case of the π 0 they were taken from our own charged-pion data [20,21], in case of the η they were interpolated from Two-Arm Photon Spectrometer (TAPS) measurements of 1.5A and 2.0A GeV Ar + Ca (Ca + Ca) reactions [11,12]. Note that for both mesons a two-slope parametrization has been used.…”

Section: A Low-mass Pairsmentioning

confidence: 99%

“…, measured with HADES in the 1.76A GeV Ar + KCl reaction [20,21] (squares linked by solid curve), compared with the corresponding neutral pion and η data from 1.5A GeV 40 Ar + nat Ca and 2.0A GeV 40 Ca + nat Ca reactions obtained with the photon calorimeter TAPS [11,12] (circles and triangles). All yields are normalized to their respective A part ; error bars shown are statistical.…”

Section: A Low-mass Pairsmentioning

confidence: 99%

“…6 the excess yields integrated over the mass region M ee = 0.15-0.5 GeV/c 2 from all available reaction systems [6,8,9]. For comparison, inclusive π 0 and η multiplicities measured in photon calorimetry with the TAPS detector [10,11] are plotted as well. Note that all yields are extrapolated to the full solid angle 3 respective average A part in order to compensate for differences in the centrality selection of the various experiments.…”

Section: B Intermediate-mass Excessmentioning

confidence: 99%

“…The π 0 and η results are from TAPS measurements in C + C (squares, solid curves) and Ca + Ca (circles, long-dashed curves) collisions [10,12]. The curves are polynomial fits to these data used to interpolate the multiplicities as a function of bombarding energy (see [11]). For easier visual comparison with the energy dependence of the dielectron excess the latter is overlayed with the π 0 curves (short-dashed) downscaled by factors of 1.8 × 10 −5 for C + C and 4.3 × 10 −5 for Ar + KCl.…”

Section: B Intermediate-mass Excessmentioning

confidence: 99%

“…These new data fully confirmed the earlier DLS result and thereby rechallenged theory to come up with a proper description of pair production at low energies. Comparing the excitation function of the excess pair multiplicity with the known π 0 and η meson production [10][11][12] revealed that the excess scales with bombarding energy very much like the pion yield does, but not at all like the η yield. This finding already suggested baryonic resonances-and mainly the (1232)-as a possible source of the e + e − excess yield.…”

Section: Introductionmentioning

confidence: 99%

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Dielectron production in Ar + KCl collisions at 1.76AGeV

Agakishiev¹,

Bałanda²,

Belver³

et al. 2011

Phys. Rev. C

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We present results on dielectron production in 40 Ar + KCl collisions at 1.76A GeV. For the first time ω mesons could be reconstructed in a heavy-ion reaction at a bombarding energy which is well below the production threshold in free nucleon-nucleon collisions. The ω multiplicity has been extracted and compared to the yields of other particles, in particular of the φ meson. At intermediate e + e − invariant masses, we find a strong enhancement of the pair yield over a reference spectrum from elementary nucleon-nucleon reactions, suggesting the onset of nontrivial effects of the nuclear medium. Transverse-mass spectra and angular distributions have been reconstructed in three invariant mass bins. In the former unexpectedly large slopes are found for high-mass pairs. The latter, in particular the helicity-angle distributions, are largely consistent with expectations for a pair cocktail dominated at intermediate masses by Dalitz decays.

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Section: A Low-mass Pairsmentioning

confidence: 99%

Section: A Low-mass Pairsmentioning

confidence: 99%

Section: B Intermediate-mass Excessmentioning

confidence: 99%

Section: B Intermediate-mass Excessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dielectron production in Ar + KCl collisions at 1.76AGeV

Agakishiev¹,

Bałanda²,

Belver³

et al. 2011

Phys. Rev. C

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High acceptance di-electron spectrometer-tool for study of hadron properties in the nuclear medium

Куглер

2000

Czech J Phys

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Dielectron Production in C+C Collisions at 2 AGeV with HADES

Przygoda

2007

Nuclear Physics A

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The invariant-mass spectrum of e e ÿ pairs produced in 12 C 12 C collisions at an incident energy of 2 GeV per nucleon has been measured for the first time. The measured pair production probabilities span over 5 orders of magnitude from the 0 -Dalitz to the =! invariant-mass region. Dalitz decays of 0 and account for all the yield up to 0:15 GeV=c 2 , but for only about 50% above this mass. A comparison with model calculations shows that the excess pair yield is likely due to baryon-resonance and vector-meson decays. Transport calculations based on vacuum spectral functions fail, however, to describe the entire mass region.The properties of hot and dense hadronic matter represent a key problem in heavy-ion physics, with far-reaching applications for other fields. They are governed by nonperturbative QCD and cannot be derived directly from the underlying Lagrangian. Models predict that hadron properties, such as mass and lifetime, depend on the temperature and density of the medium. While some hadronic many-body calculations give a broadening of the meson PRL 98, 052302 (2007)

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Contribution ofπ0and η Dalitz decays to the dilepton invariant-mass spectrum in1AGeV heavy-ion collisions

Cited by 19 publications

References 26 publications

Dielectron production in Ar + KCl collisions at 1.76AGeV

Dielectron production in Ar + KCl collisions at 1.76AGeV

High acceptance di-electron spectrometer-tool for study of hadron properties in the nuclear medium

Dielectron Production in C+C Collisions at 2 AGeV with HADES

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