# Quark Matter 2017

Feb 5 – 11, 2017
Hyatt Regency Chicago
America/Chicago timezone

## Charged-particle nuclear modification factors in PbPb and pPb collisions at 5.02 TeV with CMS

Not scheduled
2h 30m
Hyatt Regency Chicago

#### Hyatt Regency Chicago

151 East Wacker Drive Chicago, Illinois, USA, 60601
Board: F11
Poster

### Speaker

Austin Alan Baty (Massachusetts Inst. of Technology (US))

### Description

Using the 5.02 TeV collision-energy per nucleon pair PbPb and pp LHC data of 2015, CMS measured the spectra of charged particles in the $0.5 < p_{T} < 400$ GeV (pp) and $0.7 < p_{T} < 400$ GeV (PbPb) transverse momentum ranges for central rapidities. The corresponding nuclear modification factors, $R_{AA}$, are measured is several bins of centrality, from the most central 0-5% to the peripheral 70-90%. The $R_{AA}$ in the 5% most central collisions shows a maximal suppression by a factor of approximately 7-8 in the $p_{T}$ region of 6-9 GeV, followed by an increase, which continues up to the highest $p_{T}$ measured. $R_{AA}$ approaches unity in the vicinity of $p_{T}$ = 200 GeV. Comparisons of the measured nuclear modification factors are made to theory calculations and to measurements at lower collision energies. The newly measured pp spectrum is combined with the previously-published pPb spectrum to construct the pPb nuclear modification factor, $R_{pPb}$. The $R_{pPb}$ exhibits weak momentum dependence and shows a moderate enhancement above unity.

Collaboration CMS Jets and High pT Hadrons

### Primary author

Austin Alan Baty (Massachusetts Inst. of Technology (US))