High energy physics phenomenology is a branch of physics that studies the phenomena that occur at high energies, such as those found in particle accelerators or in the early universe. It involves using theoretical models and experimental data to understand the behavior of fundamental particles and the forces that govern them.

Phenomenologists in high energy physics use a variety of techniques to study phenomena at high energies, including:

1. Analyzing data from particle accelerator experiments: High energy particle accelerators, such as the Large Hadron Collider (LHC), produce high energy particles that can be used to study the fundamental properties of matter and the forces that govern it.
2. Developing theoretical models: Phenomenologists use theoretical models to make predictions about the behavior of particles and forces at high energies, and to interpret experimental data.
3. Testing theoretical predictions: Phenomenologists test the predictions of theoretical models by comparing them to experimental data. If the predictions match the data, it provides support for the theory. If the predictions do not match the data, it may be necessary to revise or modify the theory.

Overall, high energy physics phenomenology is a critical part of our understanding of the fundamental nature of matter and the universe.