In proton-proton collisions, it is not accurate to say that only one charged particle comes out. In fact, numerous charged particles can emerge from such collisions. However, it is true that in certain specific processes or interactions, only one highly energetic charged particle may be observed in the detector. This can be due to several reasons:
Dominant Interaction: In some proton-proton collisions, the dominant interaction may involve the exchange of a gauge boson, such as a photon (γ), a Z boson (Z⁰), or a W boson (W⁺ or W⁻). These interactions can result in the production of a highly energetic charged particle, while other particles produced in the collision may be less energetic or not detected due to technical limitations. Therefore, only one charged particle is observed in these specific cases.
Conservation Laws: Certain conservation laws play a role in determining the observed charged particle. For example, in high-energy proton-proton collisions, conservation of electric charge is always upheld. This means that the sum of the electric charges of the particles produced before and after the collision must be the same. If, for instance, a positively charged particle is observed, there must be accompanying negatively charged particles to conserve electric charge. However, the detection efficiency and limitations of the experimental setup may prevent the observation of all produced charged particles.
Detection Efficiency: Experimental detectors have limitations and varying efficiencies for detecting different types of particles. Some detectors may be optimized to identify and measure charged particles more accurately than neutral particles. As a result, charged particles are more likely to be observed and measured accurately compared to neutral particles, leading to the perception that only one charged particle comes out of a collision.
It's important to note that in reality, many particles are produced in high-energy collisions, including charged particles and neutral particles. The observation and identification of these particles depend on the specific experimental setup, detection techniques, and the interaction processes involved in the collision.