Exclusive production of two and four pions in proton-proton scattering

Abstract

We consider exclusive $pp\to pp{\pi }^{+}{\pi }^{-}$ and $pp\to pp{\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ reactions at high energies. The calculation is based on a tensor pomeron model and the amplitudes for the processes are formulated in an effective field-theoretic approach. In the case of $pp\to pp{\pi }^{+}{\pi }^{-}$ process we consider both diffractive and photoproduction mechanisms and we include the non-resonant ${\pi }^{+}{\pi }^{-}$ continuum and the resonance $f_0(500)$, $f_0(980)$, $f_2(1270)$, $\rho (770)$ contributions. We discuss how two pomerons couple to tensor meson $f_2(1270)$ and the interference effects of resonance and dipion continuum. We find that the relative contribution of resonances $\rho (770)$, $f_2(1270)$ and dipion continuum strongly depends on the cut on proton transverse momenta. In the case of exclusive central $4\pi$ production we include the contribution via the intermediate $\sigma \sigma$ and $\rho \rho$ states. For both processes the theoretical results have been compared with the experimental data and predictions for planned or being carried out experiments (e.g. STAR, ATLAS-ALFA) are presented.

Comments: 8 pages, 5 figures, talk presented by P. Lebiedowicz at the Low-x 2016 conference, Gyöngyös, Hungary, June 6-11, 2016. arXiv admin note: text overlap with arXiv:1606.09046