Inclusive dielectron cross sections inp+pandp+dinteractions at beam energies from 1.04 to 4.88 GeV

Abstract

Measurements of dielectron production in p + p and p + d collisions with beamkinetic energies from 1.04 to 4.88 GeV are presented. The differential cross section is presented as a function of invariant pair mass, transverse momentum, and rapidity. The shapes of the mass spectra and their evolution with beam energy provide information about the relative importance of the various dielectron production mechanisms in this energy regime. The p + d to p + p ratio of the dielectron yield is also presented as a function of invariant pair mass, transverse momentum, and rapidity. The shapes of the transverse momentum and rapidity spectra from the p + d and p + p systems are found to be similar to one another for each of the beam energies studied. The beam energy dependence of the integrated cross sections is also presented.

Inclusive dielectron production in proton-proton collisions at 2.2 GeV beam energy

“…This result suggests that our result, together with the data obtained by the DLS energy scan [13], can be used to constrain the various models aimed at describing dielectron production in few-GeV elementary reactions [8].…”

“…In this paper we supplement the available body of experimental results with data obtained on inclusive e + e − production in the p + p → p + p + e + + e − + X reaction at 2.2 GeV. A direct comparison with DLS data measured at 2.09 GeV [13] is presented. Furthermore, through the comparison with a calculated superposition of yield from various e + e − sources, commonly called the pair cocktail, we extract the inclusive production cross sections of π 0 and η mesons at 2.2 GeV.…”

“…As the HADES geometrical acceptance is substantially broader than the DLS one such a comparison can be done by projecting the reconstructed HADES dielectron yields d 3 N/dM ee dP ⊥ dY through the DLS acceptance filter [17] (here P ⊥ and Y are the e + e − pair transverse momentum and rapidity, respectively). In fact, because DLS applied to their p + p data additional cleaning cuts [13,18]-0.1 < M ee < 1.25 GeV/c 2 , P ⊥ < 1.2 GeV/c, 0.5 < Y < 1.7, and θ e > 21.5 • -an extrapolation of the HADES yield to rapidities above 1.9, as applied in Ref. [10], is not needed here.…”

“…As the former DLS experiment provided e + e − data for the p + p reaction at 2.09 GeV [13], we can make a direct comparison along the line already used to confront the DLS and HADES C + C data obtained at 1A GeV [10,17]. As the HADES geometrical acceptance is substantially broader than the DLS one such a comparison can be done by projecting the reconstructed HADES dielectron yields d 3 N/dM ee dP ⊥ dY through the DLS acceptance filter [17] (here P ⊥ and Y are the e + e − pair transverse momentum and rapidity, respectively).…”

“…Inclusive e + e − production in p + p and p + d reactions has formerly been studied in the range of [1][2][3][4][5] GeV by the dilepton spectrometer (DLS) experiment at the Bevalac facility [13] and has more recently been studied by the HADES experiment at 1.25 [7] and 3.5 GeV [8]. In particular, the comparison of the latter data sets with various model calculations demonstrated a need for improved theoretical descriptions.…”