Dilepton production in nucleon-nucleon interactions

Schäfer, M.; Dönges, H. C.; Engel, Andréas; Mosel, U.

doi:10.1016/0375-9474(94)90370-0

Cited by 58 publications

(121 citation statements)

References 22 publications

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“…At this energy also the interference between nucleon and ∆-pole terms is negligible. At high energies, where this interference becomes important [47], however, the overall contribution from these channels is negligible (see below). We, furthermore, discard e + e − production from the scalar mesons f 0 , a 0 as advocated in Ref.…”

Section: Dilepton Productionmentioning

confidence: 99%

“…In this case the strong interaction part and the electromagnetic part separate; however, the cross section for dileptons has to be corrected [45,46] by reducing the phase-space for the colliding particles in their finalstate. We discard pp bremsstrahlung from the nucleon pole since the microscopic OBE calculations [47,48,49] have shown that at 1.0 GeV the pp bremsstrahlung is smaller than the ∆ Dalitz decay contribution by a factor of 2-3. At this energy also the interference between nucleon and ∆-pole terms is negligible.…”

Section: Dilepton Productionmentioning

confidence: 99%

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Perspectives of production in , and Be reactions at SIS energies

2001

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We study dilepton production from pp, pd and pBe collisions from 1 -5 GeV including the π 0 , η, ω and ∆ Dalitz decays, direct decays of vector mesons (ρ, ω) as well as subthreshold ρ production via baryonic resonances (e.g. D 13 (1520), P 11 (1710)). Our calculations compare rather well with the pp and pd data from the DLS Collaboration, however, overestimate slightly the 'old' pBe data from that group. Futhermore, detailed predictions for differential dilepton spectra at SIS energies are made with a high mass resolution that can be controlled experimentally by the HADES Collaboration in near future.

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Section: Dilepton Productionmentioning

confidence: 99%

Section: Dilepton Productionmentioning

confidence: 99%

Perspectives of production in , and Be reactions at SIS energies

2001

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“…Since we use these Lagrangians to directly model the T-matrix, we have also included a nucleon-nucleon-axial-vector-isovector vertex, with the effective Lagrangian given by 6) where A represents the axial-vector meson field. This term is introduced because in the limit of large axial meson mass (m A ) it cures the unphysical behavior in the angular distribution of N N scattering caused by the contact term in the one-pion exchange amplitude [33], if g N N A is chosen to be…”

Section: Formalismmentioning

confidence: 99%

“…Initial interaction between two incoming nucleons is modeled by an effective Lagrangian which is based on the exchange of the π, ρ, ω and σ mesons. The coupling constants at the nucleon-nucleon-meson vertices are determined by directly fitting the T-matrices of the nucleon-nucleon (N N ) scattering in the relevant energy region [33]. The effective-Lagrangian uses the pseudovector (PV) coupling for the nucleon-nucleon-pion vertex (unlike the resonance model [22]), and thus incorporates the low energy theorems [34] of current algebra and the hypothesis of partially conserved axial-vector current (PCAC).…”

Section: Introductionmentioning

confidence: 99%

pp→pK+Λreaction in an effective Lagrangian model

Shyam

1999

Phys. Rev. C

128

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We investigate the pp → pK + Λ reaction within an effective Lagrangian model where the contributions to the amplitudes are taken into account within the tree level. The initial interaction between the two nucleons is modeled by the exchange of π, ρ, ω and σ mesons and the ΛK + production proceeds via the excitation of the N * (1650), N * (1710), N * (1720) baryonic resonances. The parameters of the model at the nucleon-nucleon-meson vertices are determined by fitting the elastic nucleon-nucleon scattering with an effective interaction based on the exchange of these four mesons, while those at the resonance vertices are calculated from the known decay widths of the resonances as well as the vector meson dominance model. Available experimental data is described well by this approach. The one-pion-exchange diagram dominates the production process at both higher and lower beam energies. The ρ and ω meson exchanges make negligible contributions. However, the σ-exchange processes contribute substantially to the total cross sections at lower beam energies. The excitation of the N * (1710) and N * (1650) resonances dominate this reaction at beam momenta above and below 3 GeV/c respectively. The interference among the amplitudes of various resonance excitation processes is significant. For beam energies very close to the K + production threshold the hyperon-proton final state interaction effects are quite important. The data is selective about the model used to describe the low energy scattering of the two final state baryons.

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“…Superimposed on our data is a calculation 14 by Haglin who uses the results of reference [12]. Another calculation by Schafer et al, 15 using a fit to elastic nucleon-nucleon data, also reproduces the general behavior of the ratio data. The behavior of the ratio as a function of energy is shown in Figure 3.…”

Section: Proton-proton and Proton-deuteron Programmentioning

confidence: 97%

Dilepton production from p-p to CaCa at the Bevalac

et al. 1995

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The DLS collaboration has recently completed a high statistics study of dilepton production at the Bevalac. In particular, we have measured dielectrons (e + e -) from p-p and p-d collisions to understand the basic dilepton production mechanisms in the energy range from 1.05 -4.9 GeV. These data can be used to determine the basic processes which contribute to nucleon-nucleon dilepton production such as hadronic bremsstrahlung, vector meson processes, and hadronic Dalitz decay. The data show that a simple elastic bremsstrahlung calculation is insufficient to explain the data. Theoretical models are compared with the data. A new high statistics study of Ca-Ca at 1.05 A⋅GeV has been made to study the collectivity of A-A collisions.

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Dilepton production in nucleon-nucleon interactions

Cited by 58 publications

References 22 publications

Perspectives of production in , and Be reactions at SIS energies

Perspectives of production in , and Be reactions at SIS energies

pp→pK+Λreaction in an effective Lagrangian model

Dilepton production from p-p to CaCa at the Bevalac

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