Reconstruction of the Sigma_c baryon using the ALICE detector

Abstract

At the end of 2017 an ALICE collaboration paper was published in which they measured a $\Lambda_c^{+}$/$\text{D}^0$ production ratio that is 5 times higher than the expected value measured by other experiments. The only difference being that the recent measurement was done in pp and p-pB collisions. A potential explanation for this deviation is that the overproduction of $\Lambda_c^{+}$ is a direct result of an increased $\Sigma_c$ production within the pp and p-pB collisions as $\Sigma_c$ decays into $\Lambda_c^{+}$ and $\pi^{\pm}$ 100$\%$ of the time. Due to the low halftime of the $\Sigma_c$-baryon, no distinction can be made between the $\Lambda_c^{+}$ from the $\Sigma_c$ and prompt $\Lambda_c^{+}$'s originating from a charm quark. In order to gain more information regarding the properties of the $\Sigma_c$-baryon, a reconstruction of the $\Sigma_c$ is attempted. This is done using Pythia8 to simulate the production of $\Sigma_c$ and looking at its decay into $\Lambda_c^+$ and $\pi^\pm$. In particular the angle of decay between the two daughter particles is studied and used to find and apply cuts in the ALICE-dataset which consists of experimental data from pp collisions at $\sqrt{s} = 6.5$ TeV. The reconstruction resulted in the observation of $\Sigma_c^{++}$ and the observation of $\Sigma_c^{0}$ both in the $p_\textrm{T}$ range of [12-16] GeV/c. Studying the angle of decay proved to be feasible in the reconstruction of the $\Sigma_c$-baryon in high $p_\textrm{T}$ ranges, but further research is required in order to confirm its discovery.