Heavy quarks in proton

The measurement of prompt photon associated with a b jet in proton-proton interactions can provide us insight into the inner structure of proton. This is because precision of determination of parton distribution functions of b quark and gluon can be increased by such a measurement. The measurement of cross-section of prompt photon associated with a b jet (process $pp\longrightarrow \gamma + b + X$) at $\sqrt{s}$= 8 TeV with the ATLAS detector is presented. Full 8 TeV dataset collected by ATLAS during the year 2012 was used in this analysis. Corresponding integrated luminosity is 20.3 $fb^{-1}$. Fiducial differential cross-section as a function of photon transverse momentum at particle level was extracted from data and compared with the prediction of leading order event generator Pythia 8. Cross-section extracted from data is normalised independently on the Monte Carlo prediction. Values of data distribution lie above Monte Carlo values. The difference can be explained by presence of higher order effects not included in the leading order event generator. The resulting integrated fiducial cross section is ( 750 $\pm$ 24 (stat) ) pb for data and ( 668 $\pm$ 10 (stat) ) pb for Monte Carlo. Statistical uncertainties only are taken into account. Fiducial region of the measurement is: $p_{T}^{\gamma}\in \left\langle 25, 1000 \right\rangle $GeV, $|\eta^{\gamma}|<1.37$ or $1.56<|\eta^{\gamma}|<2.37$, $p_{T}^{\text{jet}}>20$ GeV, $|\eta^{\text{jet}}|<2.4$, and $\Delta R (\gamma - \text{jet})$>1. This measurement is compared with results of previous experiments measuring the same or similar processes.