A signal injection test is a method used in particle physics to determine the presence of a signal, such as a Higgs boson, by simulating expected outcomes without the signal and then comparing them to outcomes with the signal included. This technique allows researchers to quantify differences in measurements and assess statistical significance, particularly in relation to the null hypothesis. If no difference is observed, upper limits on signal strength can be established, typically at 90% or 95% confidence levels, leading to colorful exclusion plots that illustrate the findings. The discussion highlights the importance of understanding these tests for accurate interpretation of experimental data.
PREREQUISITESParticle physicists, researchers involved in high-energy physics experiments, and students studying statistical methods in experimental science will benefit from this discussion.
If you do not see a difference between data and "simulation without signal", you can set an upper limit on the signal strength. If a simulated signal with some specific signal strength would lead to a significant deviation (usually: 10% or 5% probability that a downwards fluctuation gives fewer events), this signal strength is excluded at 90% (95%) confidence level.So what happens if you see the difference or not and how you quantify it ?