Investigating Baryon Stopping and Breakup in Heavy Ion Collisions

Many questions remain about the structure of the nucleon. For example, it has been suggested that its baryon number is carried by a gluonic junction, instead of by the quarks. A possible test for this junction comes from heavy-ion collisions: the ratio of electric charge to baryon number (Q/B) stopped in midrapidity post-collision. If charge and baryon number are stopped identically, this should equal the atomic number to atomic mass ratio (Z/A). Instead, recent isobar data from STAR suggests that Q/B<Z/A as would occur in a junction picture. However, more theoretical work is needed to understand this ratio. Thus, we built an optical Glauber-based model with the goal of predicting baryon and charge distributions with respect to rapidity. In our model, nucleons are stopped and become excited, then break up into baryonic and mesonic fragments, allowing for the separation of baryon number from charge. Taking into account both the initial stopping and the subsequent breakup of the nucleons, we calculated a rapidity distribution for baryon number in Au+Au collisions at √s = 200 GeV. With this model, we plan to calculate both baryon and charge distributions for different nuclei in the future and provide insight into the measurements.