Eur. Phys. J. A (2015) 51: 17
https://doi.org/10.1140/epja/i2015-15017-0

Regular Article - Theoretical Physics

Do ΞΞ bound states exist?

¹ Institute for Advanced Simulation and Jülich Center for Hadron Physics, Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany
² Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115, Bonn, Germany
³ Physik Department, Technische Universität München, D-85747, Garching, Germany

^* e-mail: j.heidenbauer@fz-juelich.de

Received: 11 December 2014
Revised: 22 January 2015
Accepted: 28 January 2015
Published online: 12 February 2015

Abstract

The existence of baryon-baryon bound states in the strangeness sector is examined in the framework of SU(3) chiral effective field theory. Specifically, the role of SU(3) symmetry breaking contact terms that arise at next-to-leading order in the employed Weinberg power counting scheme is explored. We focus on the ¹ S ₀ partial wave and on baryon-baryon channels with maximal isospin since in this case there are only two independent SU(3) symmetry breaking contact terms. At the same time, those are the channels where most of the bound states have been predicted in the past. Utilizing pp phase shifts and Σ ⁺ p cross section data allows us to pin down one of the SU(3) symmetry breaking contact terms and a clear indication for the decrease of attraction when going from the NN system to strangeness S = −2 is found, which rules out a bound state for ΣΣ with isospin I = 2. Assuming that the trend observed for S = 0 to S = −2 is not reversed when going to ΞΣ and ΞΞ makes also bound states in those systems rather unlikely.