On a possible explanation of the DLS puzzle

M. Bashkanov, H. Clement*

*Corresponding author for this work

Research output: Contribution to journalLetterpeer-review


The enhancement in the dilepton spectrum observed in heavy-ion collisions for invariant electron-positron masses in the range 0.15 GeV < Me + e- < 0.6 GeV has recently been traced back to a corresponding enhancement in np collisions relative to pp collisions. Whereas the dilepton spectra in the latter are understood quantitatively, theoretical descriptions fail to describe the much higher dilepton rate in np collisions at beam energies below 2GeV, in particular regarding the region Me + e- < 0.3 GeV. We show that the missing strength can be attributed to ρ 0-channel π + π - production, which is dominated by the t-channel ΔΔ excitation and the recently found isoscalar dibaryonic resonance structure at 2.37 GeV. These processes do not contribute in pp collisions, but only in np collisions.

Original languageEnglish
Article number107
Number of pages6
JournalEuropean Physical Journal A
Issue number7
Publication statusPublished - Jul 2014

Cite this