Thermal blurring of event-by-event fluctuations provoked by rapidity conversion

Understand

We study the effect of thermal blurring caused by the use of (momentum-space) rapidity as a proxy of coordinate-space rapidity in experimental measurements of conserved charge fluctuations in relativistic heavy ion collisions.

• In theoretical studies assuming statistical mechanics, calculated fluctuations are those in a spatial volume.
• Experiments, on the other hand, can measure fluctuations only in a momentum-space in the final state.
• In a standard argument to compare experimental results for a momentum space with theoretical studies for a coordinate space, rapidities of particles are implicitly regarded as equivalent to their coordinate-space rapidity.