Observability and Probability of Discovery in Future Experiments

We propose a method to estimate the probability of new physics discovery in future high energy physics experiments. Physics simulation gives both the average numbers $<N_b>$ of background and $<N_s>$ of signal events. We find that the proper definition of the significance is $S_{12} = \sqrt{<N_s>+<N_b>} - \sqrt{<N_b>}$ in comparison with often used significances $S_1 = \displaystyle \frac{<N_s>}{\sqrt{<N_b>}}$ and $S_2 = \displaystyle \frac{<N_s>}{\sqrt{<N_s> + <N_b>}}$. We propose a method for taking into account systematic uncertainties related to nonexact knowledge of background and signal cross sections. An account of such systematics is very essential in the search for supersymmetry at LHC. We propose a method for estimation of exclusion limits on new physics in future experiments. We also estimate the probability of new physics discovery in future experiments taking into account systematical errors.