Differential measurements of jet substructure and partonic energy loss in Au + Au collisions at sNN=200 GeV

• Published in: Physical review. C 2022-04, Vol.105 (4)
• Main Authors: Adam, J., Adams, J. R., Adkins, J. K., Aggarwal, I., Ahammed, Z., Anderson, D. M., Aschenauer, E. C., Atetalla, F. G., Bellwied, R., Bielcikova, J., Chakaberia, I., Chan, B. K., Chang, F-H, Chang, Z., Chen, J., Dedovich, T. G., Didenko, L., Duckworth, E., Engelage, J., Eppley, G., Esumi, S., Feng, Y., Fulek, L., Geurts, F., Gou, X., Han, Y., Harris, J. W., Holub, L., Huang, T., Huang, Y., Humanic, T. J., Kabir, M. L., Kauder, K., Khyzhniak, Y. V., Kosarzewski, L. K., Kumar, L., Lacey, R., Lauret, J., Lebedev, A., Lednicky, R., Lee, J. H., Liang, X., Licenik, R., Lin, T., Lin, Y., Lisa, M. A., Liu, F., Liu, H., Liu, P., Llope, W. J., Longacre, R. S., Lukow, N. S., Ma, R., Mallick, D., Margetis, S., Minaev, N. G., Mioduszewski, S., Morozov, D. A., Nemes, D. B., Nigmatkulov, G., Odyniec, G., Pawlik, B., Pokhrel, B. R., Posik, M., Quintero, A., Ray, R. L., Rogachevskiy, O. V., Romero, J. L., Salur, S., Sato, S., Seck, F., Sergeeva, M., Seyboth, P., Sheikh, A. I., Shen, D., Shi, S. S., Shi, Y., Shou, Q. Y., Sichtermann, E. P., Singha, S., Skoby, M. J., Smirnov, N., Spinka, H. M., Stewart, D. J., Strikhanov, M., Sumbera, M., Szymanski, P., Taranenko, A., Todoroki, T., Tomkiel, C. A., Tripathy, S. K., Trzeciak, B. A., Tsai, O. D., Vokal, S., Voloshin, S. A., Xu, N., Xu, Z., Zbroszczyk, H., Zhang, S., Zyzak, M.
• Format: Article
• Language: English
• Subjects: jets & heavy flavor physics; NUCLEAR PHYSICS AND RADIATION PHYSICS; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; quark & gluon jets; quark-gluon plasma; relativistic heavy-ion collisions
• ISSN: 2469-9985
• DOI: 10.1103/PhysRevC.105.044906

Here, the STAR collaboration presents jet substructure measurements related to both the momentum fraction and the opening angle within jets in $\mathrm{p+p}$ and $\mathrm{Au+Au}$ collisions at $\sqrt{s{NN}}$ =$\mathrm{200}$ $\mathrm{GeV}$. The substructure observables include SoftDrop groomed momentum fraction (zg), groomed jet radius (Rg), and subjet momentum fraction (zSJ) and opening angle (θSJ). The latter observable is introduced for the first time. Fully corrected subjet measurements are presented for $\mathrm{p+p}$ collisions and are compared to leading-order Monte Carlo models. The subjet θSJ distributions reflect the jets leading opening angle and are utilized as a proxy for the resolution scale of the medium in $\mathrm{Au+Au}$ collisions. We compare data from $\mathrm{Au+Au}$ collisions to those from $\mathrm{p+p}$ which are embedded in minimum-bias $\mathrm{Au+Au}$ events in order to include the effects of detector smearing and the heavy-ion collision underlying event. The subjet observables are shown to be more robust to the background than zg and Rg. We observe no significant modifications of the subjet observables within the two highest-energy, back-to-back jets, resulting in a distribution of opening angles and the splittings that are vacuumlike. We also report measurements of the differential dijet momentum imbalance (AJ) for jets of varying θSJ. Finally, we find no qualitative differences in energy loss signatures for varying angular scales in the range 0.1< θSJ