Improving the neutral meson raw yield extraction in ALICE

Abstract

In this bachelor thesis a new method of extracting the raw yield for neutral mesons ($\pi^0, \eta$) in ALICE is introduced. The measurement is done by the Electromagnetic Calorimeter of the ALICE detector in p-Pb collisions. The data from this measurement is used to create invariant mass distributions. Each of these mass distributions are fitted with a Gaussian function for their p$_{\mathrm{T}}$-bin. The parameters $ \mu$, $\sigma$ (and $\lambda$ for $ \pi^0$) from these Gaussians are fitted with polynomial functions to describe them as a function of p$_{\mathrm{T}}$. Due to this constraint the fluctuations of these parameters around the binpoints become less. This gives a new extracted signal. Now instead of numerical integrating the background subtracted signal this thesis will use an analytical, continuous integration from $\mu \pm$ 2$\sigma$, 3$\sigma$ and 4$\sigma$ to extract the raw yield. So there are two new raw yields, those that are integrated with and those without constraint. The values per binpoint are comparable to the values of the numerical yield, so both methods can be used. In the end the analytical raw yields combined with the numerical yields give a more realistic view at the deviation and the RMS value, since other methods are used to calculate the raw yield.