Mass tomography at different momentum ranges in quark-gluon plasma

TL;DR

This paper investigates how particle suppression in quark-gluon plasma varies with particle mass and momentum, revealing a mass hierarchy at low momentum and similar suppression across different probes at high momentum, impacting mass tomography.

Contribution

It demonstrates that mass hierarchy in suppression is due to energy loss at low momentum and shows suppression insensitivity to mass at high momentum, providing new insights into probe behavior in quark-gluon plasma.

Findings

Mass hierarchy observed at low momentum (~10 GeV) due to energy loss differences.

Suppression for different probes converges at high momentum (~100 GeV), mainly due to fragmentation functions.

High momentum single particles and jets show similar suppression, indicating insensitivity to probe mass.

Abstract

We here show that at lower momentum (i.e., $p_\perp \sim 10$GeV) single particle suppression for different types of probes exhibit a clear mass hierarchy, which is a direct consequence of the differences in the energy loss, rather than the differences in the initial distributions. On the other hand, we predict that the mass hierarchy is not expected at high momentum (i.e., $p_\perp \sim 100$GeV); i.e., while we surprisingly predict that suppression for charged hadrons will be somewhat smaller than the suppression for heavy mesons, we find that this difference will be a consequence of fragmentation functions, not the finite mass effects. That is, apart from the fragmentation functions, the probes of different masses exhibit nearly the same suppression in the high momentum region. We also argue that the same insensitivity on the probe types also appears for jets. In particular, the experimental data in the momentum regions where they exist for both types of probes, show similar suppressions of charged hadrons and inclusive jet data. Interestingly, we also find that our state-of-the-art suppression predictions for high momentum single particles are also in agreement with the jet suppression data, where the reasons behind this agreement yet remain to be understood. Finally, the available jet data also show (though with large error bars) an overlap between b jets (heavy) and inclusive jets (light) probes. Consequently, our results suggest that single particles in the momentum region below 50 GeV present an excellent tool for mass tomography, while high momentum single particles and (possibly) jets are somewhat insensitive to the details of the interaction with quark-gluon plasma.