Search for Tetraneutron by Pion Double Charge Exchange Reaction at J-PARC

TL;DR

This paper proposes using high-energy pion double charge exchange reactions at J-PARC to improve the search for the elusive tetraneutron, potentially enhancing experimental sensitivity compared to previous methods.

Contribution

It introduces a novel experimental approach employing high-energy pion beams at J-PARC to better detect tetraneutron states through DCX reactions.

Findings

Potential for increased sensitivity in tetraneutron detection.

Proposal for high-energy pion beam experiments at J-PARC.

Comparison with previous lower-energy experiments.

Abstract

Tetraneutron ($^4n$) has come back in the limelight, because of recent observation of a candidate resonant state at RIBF. We propose to investigate the pion double charge exchange (DCX) reaction, i.e. $^4\mathrm{He}({\pi}^- , {\pi}^+)$, as an alternative way to populate tetraneutron. An intense ${\pi}^-$ beam with the kinetic energy of ~850 MeV, much higher than that in past experiments at LAMPF and TRIUMF, will open up a possibility to improve the experimental sensitivity of the formation cross section, which will be much smaller than hitherto known DCX cross sections such as $^9\mathrm{Be}({\pi}^-, {\pi}^+)^9\mathrm{He}\ (g.s.)$.