One way to show that electromagnetic force and weak force does unify at high enough energy is to find two particles, which could interact through the electromagnetic force or weak force and produces different particles after the interaction. Since the products of the two interactions are different, one can tell whether the two particles have interacted through electromagnetic force or weak force by knowing what the products are, and then comparing the number of electromagnetic interactions and weak interactions. If the two forces do unify, then the number of interactions should more or less be the same at high energy because the two forces are not different anymore.

In the HERA experiment, it is possible to do this because the two particles colliding in HERA, the electron/positron and proton interact through electromagnetic force and weak force and give different results. When the particles are interacting through the electromagnetic force, an electron/positron will be produced after the interaction and the interaction is called a Neutral Current (NC) event.

On the other hand, if the particles are interacting through the weak force, a neutrino will be produced after the interaction and the interaction is called a Charged Current (CC) event.

It is not very difficult to distinguish between the two different interactions because the ZEUS detector, which is the detector in the HERA experiment, cannot detect neutrinos and therefore if there is something missing (for example, some energy, momentum) in the data detected, then the interaction is probably the Charged Current event.

In order to show that electromagnetic force and weak force unify at high energy, our group have analysed the data from the HERA experiment and counted the Neutral Current and Charged Current events and have plotted a graph correspond to the probability for the two interactions to happen.