nicely ordered jet
To me this looks like something interacted with the 2nd layer of the pixel detector and created a very-nearly symmetrical spray where a particle/antiparticle pair decayed into the same sequence of particle/antiparticle or hadron/lepton etc. resulting in two groups of tracks which are nearly mirror images of each other when viewed down the beam axis. In addition to the charged hadrons (and muons judging by the detector strikes, though one seems heavily loaded and may be an artifact), there looks to be at least one neutral hadron depositing energy in the calorimeter, though this could also be multiple charged hadrons with energy below the cut threshold for display as tracks (the curvature of the lighter/older particles' tracks at the periphery of the jet suggest to me the energies are relatively low).
A more audacious interpretation might be that all six tracks and neutral hadron detection result from a single J/psi meson decaying along its 4th most likely hadronic decay mode to 4 charged pions (2+/2-) and an omega meson which further decays into two oppositely charged pions and a neutral one (which retain slightly more of the original momentum thanks to the heavier omega, and thus don't spread as far)...
but i've only been learning about particle physics over the weekend so that is 99.9% likely to be monumental BS 😃 still a nice picture...