Abstract

We evaluate the cross section for the $p p \to p p f_{1}(1285)$ and $p \bar{p} \to p \bar{p} f_{1}(1285)$ reactions at near threshold energies relevant for the HADES and PANDA experiments at GSI-FAIR. We assume that at energies close to the threshold the $\omega \omega \to f_{1}(1285)$ and $\rho^{0} \rho^{0} \to f_{1}(1285)$ fusion processes are the dominant production mechanisms. The vertex for the $VV \to f_{1}$ coupling is derived from an effective coupling Lagrangian. The $g_{\rho \rho f_1}$ coupling constant is extracted from the decay rate of $f_{1}(1285) \to \rho^{0} \gamma$ using the vector-meson-dominance ansatz. We assume $g_{\omega \omega f_1} = g_{\rho \rho f_1}$, equality of these two coupling constants, based on arguments from the naive quark model and vector-meson dominance. The amplitude for the $VV \to f_{1}$ fusion, supplemented by phenomenological vertex form factors for the process, is given. The differential cross sections at energies close to the threshold are calculated. In order to determine the parameters of the model the $\gamma p \to f_{1}(1285) p$ reaction is discussed in addition and results are compared with the CLAS data. The possibility of a measurement by HADES@GSI is presented and discussed. We performed a Monte Carlo feasibility simulations of the $p p \to p p f_1$ reaction for $\sqrt{s}$ = 3.46 GeV in the $\pi^+ \pi^- \pi^+ \pi^-$ (not shown explicitly) and $\pi^+ \pi^- \pi^+ \pi^- \pi^0$ final states using the PLUTO generator. The latter one is especially promising as a peak in the $\pi^+ \pi^- \eta$ should be observable by HADES.

Highlights

  • The production of light axial-vector mesons with quantum numbers IGJPC 1⁄4 0þ1þþ is very interesting and was discussed in a number of experimental and theoretical papers

  • We evaluate the cross section for the pp → ppf1ð1285Þ and pp → ppf1ð1285Þ reactions at near threshold energies relevant for the HADES and PANDA experiments at GSI-FAIR

  • The region of fast growth of the cross section is related to the fast opening of the phase space, while the Reggeization is responsible for the decreasing part

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Summary

INTRODUCTION

The production of light axial-vector mesons with quantum numbers IGJPC 1⁄4 0þ1þþ is very interesting and was discussed in a number of experimental and theoretical papers. Different vector-vector-f1 vertices and corresponding transition form factors were suggested in the literature [5,6,7,8,9,10,11,12,13,14] It was suggested in [15] that a measurement of the eþe− → eþe−f1ð1285Þ reaction with double tagging at Belle II at KEK could shed new light on the γÃγÃf1 coupling with two virtual photons. The exclusive production of the f0ð1500Þ meson in antiproton-proton collisions via the pion-pion fusion mechanism was discussed for the PANDA experiment in [30]; see Fig. 3 of [31]. PANDA detector at possibilities of such measurements will be discussed in addition

THEORETICAL FRAMEWORK
Background processes to the ρρ and ργ channels of the f 1 decay in CEP
NUMERICAL RESULTS
HADES AND PANDA EXPERIMENTS
CONCLUSIONS

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