Compact Muon Solenoid
LHC, CERN
Visit us: CMS Public Website, CMS Physics ;
Contact us: CMS Publications Committee
| CMS-HIN-20-001 ; CERN-EP-2021-254 | ||
| Probing charm quark dynamics via multiparticle correlations in PbPb collisions at ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | ||
| CMS Collaboration | ||
| 23 December 2021 | ||
| Phys. Rev. Lett. 129 (2022) 022001 | ||
| Abstract: Multiparticle azimuthal correlations of prompt D$ ^{0} $ mesons are measured in PbPb collisions at a nucleon-nucleon center-of-mass energy of ${\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV. The data, collected using the CMS detector at the LHC in 2018, correspond to an integrated luminosity of 0.58 nb$^{-1}$. For the first time, a four-particle cumulant method is used to extract the second Fourier coefficient of the azimuthal distribution (${v_{2}}$) of D$ ^{0} $ mesons as a function of event centrality and the D$ ^{0} $ transverse momentum. The ratios of the four-particle ${v_{2}}$ values to previously measured two-particle cumulant results provide direct experimental access to event-by-event fluctuations of charm quark azimuthal anisotropies. These ratios are also found to be comparable to those of inclusive charged particles in the event. However, hints of deviations are seen in the most central and peripheral collisions. To investigate the origin of flow fluctuations in the charm sector, these measurements are compared with models implementing fluctuations of charm quark energy loss via collisional or radiative processes in the quark-gluon plasma. These models cannot quantitatively describe the data over the full transverse momentum and centrality ranges, although the calculations with collisional energy loss provide a better description of the data. | ||
| Links: e-print arXiv:2112.12236 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; HepData record ; CADI line (restricted) ; | ||
| Figures | |
png pdf |
Figure 1:
An example of the two-step fit of the mass spectrum (upper) and ${v_{2}^{\text {sig+bkg}}\{4\}}$ (lower) in the ${p_{\mathrm {T}}}$ interval 3-4 GeV for the centrality class 30-50%. |
png pdf |
Figure 2:
Upper panel: prompt D$ ^{0} $ meson ${v_{2}\{2\}}$ and ${v_{2}\{4\}}$ coefficients within $ {| y |} < $ 1, as a function of ${p_{\mathrm {T}}}$, for the centrality classes 10-30% (left) and 30-50% (right) from PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV. The blue solid and dashed lines denote the DABMod model calculations using Langevin dynamics for ${v_{2}\{4\}}$ and ${v_{2}\{2\}}$, respectively [11,12]. The green solid and dashed lines represent the DABMod model calculation including radiative energy loss (E-loss) for ${v_{2}\{4\}}$ and ${v_{2}\{2\}}$, respectively. Lower panel: the prompt D$ ^{0} $ meson ${{v_{2}\{4\}} / {v_{2}\{2\}}}$ ratios are shown and compared to those for charged particles [52]. The vertical bars represent statistical uncertainties and the open boxes denote the systematic uncertainties. The ${v_{2}\{2\}}$ values are measured previously by CMS in Ref. [25]. |
png pdf |
Figure 3:
Upper panel: the prompt D$ ^{0} $ meson ${v_{2}\{2\}}$ and ${v_{2}\{4\}}$ in the range $ {| y |} < $ 1 as a function of centrality for 2 $ < {p_{\mathrm {T}}} < $ 8 GeV in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV. The blue solid and dashed lines denote the DABMod model calculations with Langevin dynamics for ${v_{2}\{4\}}$ and ${v_{2}\{2\}}$, respectively [11,12]. The green solid and dashed lines represent the DABMod model calculation including radiative energy loss (E-loss). The ${v_{2}\{2\}}$ values are measured previously by CMS in Ref. [25]. Lower panel: the prompt D$ ^{0} $ meson ${{v_{2}\{4\}} / {v_{2}\{2\}}}$ are compared to the same ratio for charged particles in the pseudorapidity range $ {| \eta |} < $ 1 [52]. The vertical bars represent statistical uncertainties and open boxes denote the systematic uncertainties. The blue and green solid lines show ${{v_{2}\{4\}} / {v_{2}\{2\}}}$ under the DABMod model with Langevin and radiative E-loss transport processes, respectively. |
| Summary |
| In summary, the first measurements of the elliptic flow for prompt $\mathrm{D}^{0}$ and $\overline{\mathrm{D}}{}^{0}$ mesons using a four-particle cumulant method are presented. These ${v_{2}\{4\}}/{v_{2}\{2\}}$ values are systematically lower than the measured two-particle elliptic flow values, ${v_{2}\{2\}}$, indicating the presence of event-by-event fluctuations in the flow signal [22]. To further investigate the origin of ${v_{2}}$ fluctuations, ${v_{2}\{4\}}/{v_{2}\{2\}}$ ratios of prompt $\mathrm{D}^{0}$ mesons are compared to those of light-flavor hadrons. Similar trends for both charm mesons and light-flavor hadrons are observed, suggesting that the dominant contribution to ${v_{2}}$ fluctuations comes from the initial geometry. An indication of splitting of the ${v_{2}\{4\}}/{v_{2}\{2\}}$ ratios between charm mesons and light-flavor hadrons in the most central and most peripheral events is seen, which may suggest an additional contribution, such as energy loss fluctuations. Model calculations implementing collisional energy loss mechanisms provide a better description of the data than those considering radiative energy loss. |
| References | ||||
| 1 | BRAHMS Collaboration | Quark gluon plasma and color glass condensate at RHIC? The perspective from the BRAHMS experiment | NP A 757 (2005) 1 | nucl-ex/0410020 |
| 2 | PHOBOS Collaboration | The PHOBOS perspective on discoveries at RHIC | NP 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 | NP 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 | NP A 757 (2005) 184 | nucl-ex/0410003 |
| 5 | B. Muller, J. Schukraft, and B. Wyslouch | First results from PbPb collisions at the LHC | Ann. Rev. Nucl. Part. Sci. 62 (2012) 361 | 1202.3233 |
| 6 | N. Armesto and E. Scomparin | Heavy-ion collisions at the Large Hadron Collider: a review of the results from run 1 | EPJPlus 131 (2016) 52 | 1511.02151 |
| 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 | A. M. Poskanzer and S. A. Voloshin | Methods for analyzing anisotropic flow in relativistic nuclear collisions | PRC 58 (1998) 1671 | nucl-ex/9805001 |
| 10 | J.-Y. Ollitrault, A. M. Poskanzer, and S. A. Voloshin | Effect of flow fluctuations and nonflow on elliptic flow methods | PRC 80 (2009) 014904 | 0904.2315 |
| 11 | R. Katz et al. | Sensitivity study with a D and B mesons modular simulation code of heavy flavor $ R_{AA} $ and azimuthal anisotropies based on beam energy, initial conditions, hadronization, and suppression mechanisms | PRC 102 (2020) 024906 | 1906.10768 |
| 12 | R. Katz, C. A. G. Prado, J. Noronha-Hostler, and A. A. P. Suaide | System-size scan of D meson $ R_{AA} $ and $ v_n $ using PbPb, XeXe, ArAr, and OO collisions at energies available at the CERN Large Hadron Collider | PRC 102 (2020) 041901(R) | 1907.03308 |
| 13 | J. W. Harris | Introduction to hard scattering processes and recent results from hard probes at RHIC and LHC | in XXXVII Brazilian Meeting on Nuclear Physics, 2015 | |
| 14 | 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 |
| 15 | CMS Collaboration | Measurement of prompt $ {\mathrm{D^0}} $ meson azimuthal anisotropy in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PRL 120 (2018) 202301 | CMS-HIN-16-007 1708.03497 |
| 16 | ALICE Collaboration | Event-shape engineering for the D-meson elliptic flow in mid-central Pb-Pb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | JHEP 02 (2019) 150 | 1809.09371 |
| 17 | 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 |
| 18 | CMS Collaboration | Measurement of prompt $ {\mathrm{D^0}} $ and $ {\mathrm{\overline{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 |
| 19 | CMS Collaboration | Suppression and azimuthal anisotropy of prompt and nonprompt $ \mathrm{J}/\psi $ production in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 2.76 TeV | EPJC 77 (2017) 252 | CMS-HIN-14-005 1610.00613 |
| 20 | ALICE Collaboration | $ \mathrm{J}/\psi $ elliptic flow in Pb-Pb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PRL 119 (2017) 242301 | 1709.05260 |
| 21 | 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 |
| 22 | 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 |
| 23 | ALICE Collaboration | Elliptic flow of electrons from beauty-hadron decays in Pb-Pb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PRL 126 (2021) 162001 | 2005.11130 |
| 24 | ALICE Collaboration | Measurement of $ \Upsilon$(1S) elliptic flow at forward rapidity in Pb-Pb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PRL 123 (2019) 192301 | 1907.03169 |
| 25 | CMS Collaboration | Measurement of the azimuthal anisotropy of $ \Upsilon$(1S) and $ \Upsilon$(2S) mesons in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PLB 819 (2021) 136385 | CMS-HIN-19-002 2006.07707 |
| 26 | M. Luzum and J.-Y. Ollitrault | Eliminating experimental bias in anisotropic-flow measurements of high-energy nuclear collisions | PRC 87 (2013) 044907 | arXiv:nucl-ex/1209.2323 |
| 27 | STAR Collaboration | Elliptic flow from two and four particle correlations in Au+Au collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 130 GeV | PRC 66 (2002) 034904 | arXiv:nucl-ex/0206001 |
| 28 | STAR Collaboration | Measurement of $ {\mathrm{D^0}} $ azimuthal anisotropy at midrapidity in Au+Au collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 200 GeV | PRL 118 (2017) 212301 | 1701.06060 |
| 29 | S. A. Voloshin, A. M. Poskanzer, A. Tang, and G. Wang | Elliptic flow in the gaussian model of eccentricity fluctuations | PLB 659 (2008) 537 | 0708.0800 |
| 30 | A. Bilandzic, R. Snellings, and S. Voloshin | Flow analysis with cumulants: Direct calculations | PRC 83 (2011) 044913 | 1010.0233 |
| 31 | J. Noronha-Hostler et al. | Cumulants and nonlinear response of high $ {p_{\mathrm{T}}} $ harmonic flow at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PRC 95 (2017) 044901 | 1609.05171 |
| 32 | CMS Collaboration | HEPData record for this analysis | link | |
| 33 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | CMS-00-001 |
| 34 | 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 |
| 35 | CMS Collaboration | The CMS trigger system | JINST 12 (2017) P01020 | CMS-TRG-12-001 1609.02366 |
| 36 | CMS Collaboration | Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at $ \sqrt{s} = $ 8 TeV | JINST 10 (2015) P06005 | CMS-EGM-13-001 1502.02701 |
| 37 | 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 |
| 38 | CMS Collaboration | Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at $ \sqrt{s}= $ 8 TeV | JINST 10 (2015) P08010 | CMS-EGM-14-001 1502.02702 |
| 39 | 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 |
| 40 | CMS Collaboration | Observation and studies of jet quenching in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 2.76 TeV | PRC 84 (2011) 024906 | CMS-HIN-10-004 1102.1957 |
| 41 | T. Sjostrand et al. | An introduction to PYTHIA 8.2 | CPC 191 (2015) 159 | 1410.3012 |
| 42 | CMS Collaboration | Extraction and validation of a new set of CMS PYTHIA-8 tunes from underlying-event measurements | EPJC 80 (2020) 4 | CMS-GEN-17-001 1903.12179 |
| 43 | 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 |
| 44 | Particle Data Group, P. A. Zyla et al. | Review of particle physics | Prog. Theor. Exp. Phys. 2020 (2020) 083C01 | |
| 45 | G. E. Forden and D. H. Saxon | Improving vertex position determination by using a kinematic fit | NIMA 248 (1986) 439 | |
| 46 | H. Voss, A. Hocker, J. Stelzer, and F. Tegenfeldt | TMVA, the toolkit for multivariate data analysis with ROOT | in XIth International Workshop on Advanced Computing and Analysis Techniques in Physics Research (ACAT), p. 40 2007 [PoS(ACAT)040] | physics/0703039 |
| 47 | A. Bilandzic et al. | Generic framework for anisotropic flow analyses with multiparticle azimuthal correlations | PRC 89 (2014) 064904 | 1312.3572 |
| 48 | CMS Collaboration | Evidence for collective multiparticle correlations in pPb collisions | PRL 115 (2015) 012301 | CMS-HIN-14-006 1502.05382 |
| 49 | N. Borghini, P. M. Dinh, and J.-Y. Ollitrault | Flow analysis from multiparticle azimuthal correlations | PRC 64 (2001) 054901 | nucl-th/0105040 |
| 50 | CMS Collaboration | Multiplicity and transverse momentum dependence of two- and four-particle correlations in pPb and PbPb collisions | PLB 724 (2013) 213 | CMS-HIN-13-002 1305.0609 |
| 51 | M. J. Oreglia | A study of the reactions $\psi' \to \gamma\gamma \psi$ | PhD thesis, Stanford University, 1980 SLAC Report SLAC-R-236, see Appendix D | |
| 52 | CMS Collaboration | Studies of charm and beauty hadron long-range correlations in pp and pPb collisions at LHC energies | PLB 813 (2021) 136036 | CMS-HIN-19-009 2009.07065 |
| 53 | CMS Collaboration | Azimuthal anisotropy of charged particles with transverse momentum up to 100 GeV/$c$ in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PLB 776 (2018) 195 | CMS-HIN-15-014 1702.00630 |
| 54 | CMS Collaboration | Non-Gaussian elliptic-flow fluctuations in PbPb collisions at $ {\sqrt {\smash [b]{s_{_{\mathrm {NN}}}}}} = $ 5.02 TeV | PLB 789 (2019) 643 | CMS-HIN-16-019 1711.05594 |
|
|
Compact Muon Solenoid LHC, CERN |
|
|
|
|
|
|