New Insights into Charged Hadrons from Lead-Lead Collisions at the LHC

Recent measurements of pseudorapidity distributions of charged hadrons in lead-lead collisions have been reported, highlighting significant findings from the CMS Collaboration. The data was collected at the Large Hadron Collider (LHC) during 2022, achieving a nucleon-nucleon center-of-mass energy of ( \sqrt{s_{NN}} = 5.36 \text{ TeV} ). This study utilized an integrated luminosity of ( 0.30 \pm 0.03 \mu\text{b}^{-1} ) and focused on primary charged hadrons produced within the pseudorapidity range of ( |\eta| < 2.6 ).

Key results indicate that in the 5% most central collisions, the charged-hadron density in the range ( |\eta| < 0.5 ) was measured to be ( 2032 \pm 91 ) (systematic uncertainty), with negligible statistical uncertainty. This finding aligns with extrapolations from previous nucleus-nucleus collision data at lower energies. The study also examined how particle production varies with collision energy and initial collision geometry, providing insights into the dynamics of heavy-ion collisions.

Comparisons were made with various Monte Carlo event generators and previous measurements from lead-lead and xenon-xenon collisions at similar energies. These results contribute to a deeper understanding of the behavior of matter under extreme conditions, which is essential for exploring the properties of the quark-gluon plasma and the fundamental forces at play in the universe.

The full paper, titled "Pseudorapidity distributions of charged hadrons in lead-lead collisions at ( \sqrt{s_{NN}} = 5.36 \text{ TeV} )" by the CMS Collaboration, can be accessed on arXiv with the identifier ( arXiv:2409.00838 ).