A measurement of single top quark production $t-$channel cross-section in proton-proton collisions at an energy in the centre-of-mass of $\sqrt{s}=5.02 \ \text{TeV}$ with $257 \ \text{pb}^{-1}$ of data collected by the ATLAS experiment at LHC is reported.
This analysis applies event selections to identify $t-$channel single top candidate events decaying semi-leptonically. Selected events are then used to train a Boosted Decision Tree (BDT) to optimize signal versus background separation. A Profile-Likelihood (PL) fit is performed to measure the total cross-section $\sigma(tq + \bar{t}q)$ and the ratio between the top quark ($tq$), and anti-top quark ($\bar{t}q$) cross-sections $R_t$. The analysis uses forward jets to enhance the $t-$channel significance (jet $\eta < 4.0$). Measured values of the cross-section $\sigma(tq + \bar{t}q) = 6.6^{+4.3}_{-4.0} (\text{stat.})~^{+4.4}_{-3.6} (\text{syst.})$ and of the ratio $R_t = 2.74^{+1.44}_{-0.83} (\text{stat.})~^{+1.04}_{-0.29} (\text{syst.})$ are well in agreement with Standard Model (SM) predictions.