Title

Constraints on the Initial State of Pb-Pb Collisions via Measurements of Z -Boson Yields and Azimuthal Anisotropy at sNN =5.02 TeV

Document Type

Article

Abstract

The CMS experiment at the LHC has measured the differential cross sections of Z bosons decaying to pairs of leptons, as functions of transverse momentum and rapidity, in lead-lead collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The measured Z boson elliptic azimuthal anisotropy coefficient is compatible with zero, showing that Z bosons do not experience significant final-state interactions in the medium produced in the collision. Yields of Z bosons are compared to Glauber model predictions and are found to deviate from these expectations in peripheral collisions, indicating the presence of initial collision geometry and centrality selection effects. The precision of the measurement allows, for the first time, for a data-driven determination of the nucleon-nucleon integrated luminosity as a function of lead-lead centrality, thereby eliminating the need for its estimation based on a Glauber model.

Department(s)

Physics and Engineering

Publication Title

Physical Review Letters

Volume

127

Issue

10

Publication Date

9-3-2021

DOI

10.1103/PhysRevLett.127.102002

ISSN

00319007

E-ISSN

10797114

PubMed ID

34533355

Comments

The CMS Collaboration includes over 100 authors. This record includes the Bethel author and the first 5 authors listed. The full list of authors can be viewed on the downloaded document or at the original publisher's website - https://doi.org/10.1103/PhysRevLett.127.102002

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