Antiproton production in pp, dp and dd collisions close to threshold

Abstract

The production of antiprotons in pp collisions is investigated close to threshold where experimental data about the total cross section are not available. We analyze the latter reaction within the LUND string model for inclusivep production and within the framework of a one-boson exchange model for the exclusive reaction pp → pppp. The application of our new results to the analysis of subthreshold antiproton production in d + p and d + d collisions shows cross sections that are much lower than expected before. Nevertheless, the comparison of experimentalp differential cross sections from d+ p and d+ d is expected to provide valuable information about a nonnucleonic component in the deuteronwavefunction. * supported by BMBF and the Russia Foundation for the fundamental Research

Kaon versus antikaon production at SIS energies

“…This recipe might be still a matter of debate; however, our findings in Refs. [29,30,31,32,33] indicate, that the production is essentially dominated by phase space close to threshold and thus a scaling in s 0 /s should be a good approximation. The isospin averaged production cross section of a K + Λ and K + Σ pair in a nucleonnucleon collision is related to the measured isospin channels as:…”

“…It has recently been argued that extrapolations from high energy data [28] used in [26] overestimate the elementary K − yield by more than an order of magnitude close to threshold [29,30,31] such that a reanalysis of this question in nucleus-nucleus reactions appears necessary. In previous works we have calculated -within boson exchange models -the near threshold production cross section for antiprotons [32], vector mesons (ρ, ω, Φ) [33] as well as antikaons [31] from nucleon-nucleon as well as pion-nucleon reactions (cf. also Ref.…”

Reanalysis of antiproton production in proton-nucleus and nucleus-nucleus reactions at subthreshold energies

“…As in Refs. [24,38] we will complement the inclusive production of antiprotons at high energies by calculations within the LUND string model [39] (LSM) to include additionally a multi-hadronic final state with more than two nucleons and an antiproton in the final state. Fig.…”

“…In order to calculate σ π i→pN we address to available experimental data for the inverse reaction pp → ππ, πρ as in Ref. [24] which are related by detailed balance as…”

Probing the deuteron structure at small NN distances by antiproton-deuteron annihilation

“…In principle, the two-step mechanism can give some sizeable contribution to this spectrum at m 2π − ∼ 0.8 − 1.1(GeV /c 2 ). However, it is very difficult to calculate it accurately because there is a large uncertainty related to the off-shellness of the virtual meson in the intermediate state [18,19]. Thus, according to the above this ∆∆ component can contribute in the high mass kinematical region where the two-step mechanism of the annihilation processpd → 2π − π + p can be neglected.…”