Kaon pair production in proton-proton collisions

Abstract

The differential and total cross sections for kaon pair production in the pp → ppK + K − reaction have been measured at three beam energies of 2.65, 2.70, and 2.83 GeV using the ANKE magnetic spectrometer at the COSY-Jülich accelerator. These near-threshold data are separated into pairs arising from the decay of the φ-meson and the remainder. For the non-φ selection, the ratio of the differential cross sections in terms of the K − p and K + p invariant masses is strongly peaked towards low masses. This effect can be described quantitatively by using a simple ansatz for the K − p final state interaction, where it is seen that the data are sensitive to the magnitude of an effective K − p scattering length. When allowance is made for a small number of φ events where the K − rescatters from the proton, the φ region is equally well described at all three energies. A very similar phenomenon is discovered in the ratio of the cross sections as functions of the K − pp and K + pp invariant masses and the identical final state interaction model is also very successful here. The world data on the energy dependence of the non-φ total cross section is also reproduced, except possibly for the results closest to threshold.

Associated strangeness production in thepp→pK+K−pandXie1, Wilkin2 2010Phys. Rev. C

“…We show that the pion-induced data are indeed compatible with the large N * (1535) : (1405)K coupling resulting from the ss components in the N * (1535). The resulting theoretical estimates of the pp → pK + K − p and pp → pK + π 0 0 differential and total cross sections describe well the available COSY experimental data [27,29].…”

“…In parallel with the (1405) measurement, Maeda et al also extracted differential and total cross sections for kaon pair production in the pp → ppK + K − reaction [29]. These results show clear evidence for the excitation and decay of the φ meson sitting on a smooth K + K − background, whose shape resembles phase space.…”

“…The parameters α = −20.5 MeV/c and β = 166.7 MeV/c [40] give a slightly stronger pp FSI in the near-threshold region than that used in the experimental article [29]. The normalization is chosen such that the differential cross section is…”

“…The results of the present calculation are compared with experimental data from Refs. [29] (closed circles), [42] (open square), [43] (closed squares), and [44] (open circle).…”

“…This would, of course, only be relevant for the isospin I = 0 K − p contribution, but this is likely to dominate the low-mass region because of the presence of the (1405). It is therefore the purpose of the present article to analyze simultaneously the available data on pp → K + p 0 π 0 and pp → K + pK − p production at a beam energy of 2.83 GeV [27,29] within a unified phenomenological model, where the N * (1535) acts as a doorway state for both production processes.…”