Three-baryon femtoscopy as an effective 3→3 scattering experiment at ALICE

About

Three-body forces in nuclear physics account for effects that cannot be captured by pairwise interactions alone in many-body systems. These forces have traditionally been constrained through two-body scattering experiments and measurements of bound-state properties. Direct experimental information on three-body dynamics in well-controlled systems of three free, unbound particles has so far been inaccessible due to the lack of a suitable experimental technique, leaving a significant part of the three-body continuum unexplored.

In this seminar, I will present the first femtoscopic measurement of the genuine three-proton correlation function in pp collisions at 13.6 TeV with ALICE at the LHC. This observable encodes information about the final-state interactions among three protons emitted at femtometer-scale separations in the collision. Direct comparison with state-of-the-art three-body calculations reveals sensitivity to the partial-wave structure of the nuclear interaction, establishing three-baryon femtoscopy as an effective scattering experiment with unbound nucleons in a 3→3 process that is not feasible with any other experimental method. The measurement also reveals the first experimental signature of an effective long-range attraction emerging from three-body continuum dynamics.

The newly established method will make it possible to exploit the abundant production of hadrons at the LHC to investigate three-body interactions that are poorly constrained or entirely unknown. I will conclude with a discussion of future measurements of three-body interactions involving hyperons, which could have important implications for hypernuclear physics and for the equation of state of dense matter, including that found in neutron stars.

Coffee will be served at 10h30

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