> Baryons, particles containing three quarks, carry a baryon number of 1. The total baryon number has been conserved since shortly after the Big Bang. However, it is still unknown what it is inside the baryons, either the quarks or the gluons that bind them, that carries the baryon number. The STAR Collaboration presents evidence from three types of collisions that can help to distinguish between the two scenarios (see the Perspective by Li). The data disfavor the hypothesis that quarks are the carriers of the baryon number.
— "Tracking the baryon number with nuclear collisions" https://doi.org/10.1126/science.ads5962
That 'Perspective', slightly earlier in the issue, has this abstract; it is either more, or less, instructive than the above depending on one's familiarity with the topic:
> The proton sits at the heart of every atom. It was once pictured as a cluster of three quarks—constituents of matter whose properties combine to produce the proton’s characteristics. Increasingly precise experiments have repeatedly challenged this classical view by revealing that a proton is not merely the sum of quarks, but a many-body system whose defining properties (such as mass and spin) arise from the collective dynamics of quarks and the gluons that bind them together (1, 2). Yet, the origin of the proton’s baryon number—a conserved quantity that distinguishes matter from antimatter—has remained elusive. On page 727 of this issue, the STAR Collaboration (3) reports experimental measurements that could resolve a decades-old debate over how baryon number is carried and transported. The findings offer insights into the origin of the proton’s identity and how matter is organized throughout the Universe.
— "The proton's next secret" https://doi.org/10.1126/science.aek0574