CMS-HIN-24-006

CMS-HIN-24-006 ; CERN-EP-2025-250
Influence of strangeness on the anisotropic flow of prompt $ \mathrm{D}_{s}^{\pm} $ mesons in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV
CMS Collaboration
15 February 2026
Submitted to Physics Letters B
Abstract: The azimuthal anisotropy of prompt $ \mathrm{D}_{s}^{\pm} $ mesons produced in lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV is measured using data obtained with the CMS detector. The dataset corresponds to an integrated luminosity of 0.58$ \text{nb}^{-1}$. The azimuthal anisotropy of heavy charmed mesons provides a key constraint on the interactions of charm quarks with the quark-gluon plasma (QGP) medium. These interactions include coalescence mechanisms and parton energy loss in the QGP. The anisotropy is quantified by the second- ($ v_{2} $) and third-order ($ v_{3} $) Fourier coefficients of the azimuthal distribution of the $ \mathrm{D}_{s}^{\pm} $ mesons. The $ v_{2} $ coefficient is determined in the transverse momentum range 4 $ < p_{\mathrm{T}} < $ 40 GeV for three event centrality classes, while the $ v_{3} $ coefficient is measured in the range 4 $ < p_{\mathrm{T}} < $ 20 GeV for a single event centrality class. The results for the $ \mathrm{D}_{s}^{\pm} $ mesons are compared to those previously measured for $ \mathrm{D^0} $ mesons. The azimuthal anisotropy coefficients for $ \mathrm{D}_{s}^{\pm} $ and $ \mathrm{D^0} $ mesons are found to be consistent within the precision of this measurement, suggesting that the strangeness content of the $ \mathrm{D}_{s}^{\pm} $ meson does not significantly alter its azimuthal distribution within the measured $ p_{\mathrm{T}} $ range.
Links: e-print arXiv:2602.14221 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ;

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: The left plot shows an example of the invariant mass ($ m_{\text{inv}} $) spectrum fit for $ \mathrm{D}_{s}^{\pm} $ candidates in the $ \mathrm{D}_{s}^{\pm} p_{\mathrm{T}} $ interval 6--8 GeV for the centrality class 10--30%. The middle and right plots show examples of the simultaneous fit where the $ v_n $ value of the combined signal and background ($ {v_n}^\mathrm{Sig+Bkg} $) is modeled as a function of the invariant mass. The horizontal lines represent the $ m_{\text{inv}} $ mass binning and the vertical lines (largely concealed by the corresponding markers) represent the statistical uncertainty.
png pdf	Figure 2: The $ v_{2} $ coefficients for prompt $ \mathrm{D}_{s}^{\pm} $ and prompt $ \mathrm{D^0} $ (from Ref. [17]) mesons as a function of $ \mathrm{D}_{s}^{\pm} p_{\mathrm{T}} $ for the 0--10% (left), 10--30% (middle), and 30-50% (right) centrality classes. The hatched area shown on top of the ALICE $ v_{2} $ results [48] in the 30--50% centrality class represents the contribution to the systematic uncertainty of the non-prompt contribution. The horizontal lines represent the $ p_{\mathrm{T}} $ bin ranges. The vertical bars and the boxes represent statistical and systematic uncertainties, respectively.
png pdf	Figure 3: The $ v_{3} $ coefficients for prompt $ \mathrm{D}_{s}^{\pm} $ and prompt $ \mathrm{D^0} $ (from Ref. [17]) mesons as a function of $ \mathrm{D}_{s}^{\pm} p_{\mathrm{T}} $ for the 10--30% centrality class. The horizontal lines represent the $ p_{\mathrm{T}} $ bin ranges. The vertical bars and the boxes represent statistical and systematic uncertainties, respectively.

Tables
png pdf	Table 1: Summary of systematic uncertainties in the absolute differences between the nominal and the alternative analyses for the $ v_{2} $ and $ v_{3} $ values.

Summary

The elliptic flow $ v_{2} $ and triangular flow $ v_{3} $ Fourier coefficients for prompt $ \mathrm{D}_{s}^{\pm} $ mesons in lead-lead (PbPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV have been measured using the CMS detector at the CERN LHC. The $ v_{2} $ results for transverse momenta in the range 4 $ < p_{\mathrm{T}} < $ 40 GeV are presented in three ranges of collision centrality, corresponding to central, mid-central, and peripheral collisions. The $ v_{3} $ results in the range 4 $ < p_{\mathrm{T}} < $ 20 GeV are presented for mid-central collisions. The analysis employs the full rapidity coverage $ |y| < $ 2.4 of the CMS detector. The $ v_{2} $ results are measured with a precision that allows for a detailed comparison to $ \mathrm{D^0} $ mesons. The coefficients show a clear ordering by centrality and a pronounced $ p_{\mathrm{T}} $ dependence in the 10--30% centrality class. A non-zero $ v_{3} $ coefficient is also seen for 4 $ < p_{\mathrm{T}} < $ 10 GeV, suggesting the influence of initial-state geometry fluctuations in $ \mathrm{D}_{s}^{\pm} $ meson production. The $ v_{2} $ and $ v_{3} $ coefficients of the $ \mathrm{D}_{s}^{\pm} $ mesons, which contain a strange quark, are compared to those previously measured for non-strange $ \mathrm{D^0} $ mesons. The azimuthal anisotropies of $ \mathrm{D}_{s}^{\pm} $ and $ \mathrm{D^0} $ mesons are found to be consistent within the measured $ p_{\mathrm{T}} $ range. This result indicates that the anisotropies are dominated by the parent charm quark evolution in the QGP and that the underlying physics mechanisms, whether coalescence at low $ p_{\mathrm{T}} $ or path-length dependent energy loss at high $ p_{\mathrm{T}} $, are not strongly sensitive to the flavor of the light quark involved in hadronization.

References
1	BRAHMS Collaboration	Quark-gluon plasma and color glass condensate at RHIC? The perspective from the BRAHMS experiment	Nucl. Phys. A 757 (2005) 1	nucl-ex/0410020
2	PHOBOS Collaboration	The PHOBOS perspective on discoveries at RHIC	Nucl. Phys. A 757 (2005) 28	nucl-ex/0410022
3	STAR Collaboration	Experimental and theoretical challenges in the search for the quark-gluon plasma: the STAR Collaboration's critical assessment of the evidence from RHIC collisions	Nucl. Phys. A 757 (2005) 102	nucl-ex/0501009
4	PHENIX Collaboration	Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: experimental evaluation by the PHENIX Collaboration	Nucl. Phys. A 757 (2005) 184	nucl-ex/0410003
5	CMS Collaboration	Overview of high-density QCD studies with the CMS experiment at the LHC	Phys. Repts. 1115 (2025) 219	CMS-HIN-23-011 2405.10785
6	J.-Y. Ollitrault	Anisotropy as a signature of transverse collective flow	PRD 46 (1992) 229
7	U. Heinz and R. Snellings	Collective flow and viscosity in relativistic heavy-ion collisions	Ann. Rev. Nucl. Part. Sci. 63 (2013) 123	1301.2826
8	C. Gale, S. Jeon, and B. Schenke	Hydrodynamic modeling of heavy-ion collisions	Int. J. Mod. Phys. A 28 (2013) 1340011	1301.5893
9	B. Alver and G. Roland	Collision-geometry fluctuations and triangular flow in heavy-ion collisions	Phys. Rev. C 81 (2010) 054905	1003.0194
10	F. Prino and R. Rapp	Open heavy flavor in QCD matter and in nuclear collisions	JPG 43 (2016) 093002	1603.00529
11	R. Rapp et al.	Extraction of heavy-flavor transport coefficients in QCD matter	Nucl. Phys. A 979 (2018) 21	1803.03824
12	H. van Hees, V. Greco, and R. Rapp	Heavy-quark probes of the quark-gluon plasma and interpretation of recent data taken at the BNL Relativistic Heavy Ion Collider	Phys. Rev. C 73 (2006) 034913	nucl-th/0508055
13	M. Gyulassy, I. Vitev, and X.-N. Wang	High $ p_{\mathrm{T}} $ azimuthal asymmetry in noncentral A+A at RHIC	PRL 86 (2001) 2537	nucl-th/0012092
14	E. V. Shuryak	Azimuthal asymmetry at large $ p_{\mathrm{T}} $ seem to be too large for a pure 'jet quenching'	Phys. Rev. C 66 (2002) 027902	nucl-th/0112042
15	ALICE Collaboration	D-meson azimuthal anisotropy in midcentral Pb-Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV	PRL 120 (2018) 102301	1707.01005
16	CMS Collaboration	Measurement of prompt $ \mathrm{D^0} $ meson azimuthal anisotropy in Pb-Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV	PRL 120 (2018) 202301	CMS-HIN-16-007 1708.03497
17	CMS Collaboration	Measurement of prompt $ \mathrm{D}^0 $ and $ \overline{\mathrm{D}}^0 $ meson azimuthal anisotropy and search for strong electric fields in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV	PLB 816 (2021) 136253	CMS-HIN-19-008 2009.12628
18	ATLAS Collaboration	Measurement of azimuthal anisotropy of muons from charm and bottom hadrons in Pb+Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the ATLAS detector	PLB 807 (2020) 135595	2003.03565
19	ALICE Collaboration	$ \mathrm{J}/\psi $ elliptic and triangular flow in Pb-Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV	JHEP 10 (2020) 141	2005.14518
20	ALICE Collaboration	Transverse-momentum and event-shape dependence of D-meson flow harmonics in Pb-Pb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV	PLB 813 (2021) 136054	2005.11131
21	CMS Collaboration	Probing charm quark dynamics via multiparticle correlations in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV	PRL 129 (2022) 022001	CMS-HIN-20-001 2112.12236
22	CMS Collaboration	Measurements of the azimuthal anisotropy of prompt and non-prompt charmonia in PbPb collisions at 5.02 TeV	JHEP 10 (2023) 115
23	P. Koch, B. M \"u ller, and J. Rafelski	Strangeness in relativistic heavy ion collisions	Phys. Repts. 142 (1986) 167
24	ALICE Collaboration	Multi-strange baryon production at mid-rapidity in PbPb collisions at 2.76 tev	PLB 728 (2014) 216
25	CMS Collaboration	HEPData record for this analysis	link
26	CMS Collaboration	Development of the CMS detector for the CERN LHC Run 3	JINST 19 (2024) P05064
27	CMS Collaboration	Performance of the CMS level-1 trigger in proton-proton collisions at $ \sqrt{s} = $ 13 TeV	JINST 15 (2020) P10017	CMS-TRG-17-001 2006.10165
28	CMS Collaboration	Performance of the CMS high-level trigger during LHC Run 2	JINST 19 (2024) P11021
29	CMS Collaboration	Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC	JINST 16 (2021) P05014	CMS-EGM-17-001 2012.06888
30	CMS Collaboration	Performance of the CMS muon detector and muon reconstruction with proton-proton collisions at $ \sqrt{s}= $ 13 TeV	JINST 13 (2018) P06015	CMS-MUO-16-001 1804.04528
31	CMS Collaboration	Description and performance of track and primary-vertex reconstruction with the CMS tracker	JINST 9 (2014) P10009	CMS-TRK-11-001 1405.6569
32	CMS Collaboration	Precision luminosity measurement in proton-proton collisions at $ \sqrt{s}= $ 13 TeV in 2015 and 2016 at CMS	EPJC 81 (2021) 800	CMS-LUM-17-003 2104.01927
33	CMS Collaboration	Luminosity measurement for lead-lead collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV in 2015 and 2018 at CMS	Submitted to EPJC, 2025	CMS-LUM-20-002 2503.03946
34	A. J. Baltz et al.	The Physics of Ultraperipheral Collisions at the LHC	Phys. Rept. 458 (2008) 1	0706.3356
35	CMS Collaboration	Observation and studies of jet quenching in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 2.76 TeV	Phys. Rev. C 84 (2011) 024906	CMS-HIN-10-004 1102.1957
36	T. Sjöstrand et al.	An introduction to PYTHIA 8.2	Comput. Phys. Commun. 191 (2015) 159	1410.3012
37	CMS Collaboration	Extraction and validation of a new set of CMS PYTHIA8 tunes from underlying-event measurements	EPJC 80 (2020) 4	CMS-GEN-17-001 1903.12179
38	D. J. Lange	The EVTGEN particle decay simulation package	NIM A 462 (2001) 152
39	I. P. Lokhtin and A. M. Snigirev	A model of jet quenching in ultrarelativistic heavy ion collisions and high-$ p_{\mathrm{T}} $ hadron spectra at RHIC	EPJC 45 (2006) 211	hep-ph/0506189
40	CMS Collaboration	Charged-particle nuclear modification factors in PbPb and pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV	JHEP 04 (2017) 039	CMS-HIN-15-015 1611.01664
41	GEANT4 Collaboration	GEANT 4---a simulation toolkit	NIM A 506 (2003) 250
42	Particle Data Group , R. L. Workman et al.	Review of particle physics	PRD 110 (2024) 030001
43	A. Hocker et al.	TMVA --- toolkit for multivariate data analysis	PoS ACAT 04 (2007) 0	physics/0703039
44	STAR Collaboration	Elliptic flow from two- and four-particle correlations in Au+Au collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 130 GeV	Phys. Rev. C 66 (2002) 034904	nucl-ex/0206001
45	A. M. Poskanzer and S. A. Voloshin	Methods for analyzing anisotropic flow in relativistic nuclear collisions	Phys. Rev. C 58 (1998) 1671	nucl-ex/9805001
46	NA49 Collaboration	Directed and elliptic flow of charged pions and protons in Pb+Pb collisions at 40A and 158A GeV	Phys. Rev. C 68 (2003) 034903	nucl-ex/0303001
47	CMS Collaboration	Study of charm hadronization with prompt $ \Lambda_{c}^{+} $ baryons in proton-proton and lead-lead collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV	JHEP 01 (2024) 128	CMS-HIN-21-004 2307.11186
48	ALICE Collaboration	Measurement of prompt $ \mathrm{D}_{s}^{\pm} $ meson production and azimuthal anisotropy in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV	PLB 827 (2022) 136986	2110.10006