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| CMS-HIN-21-012 ; CERN-EP-2024-011 | ||
| Correlations between azimuthal anisotropy and mean transverse momentum in pp, pPb, and peripheral PbPb collisions | ||
| CMS Collaboration | ||
| 6 October 2024 | ||
| Submitted to Phys. Rev. Lett. | ||
| Abstract: Correlations between azimuthal anisotropy and mean transverse momentum of charged particles in proton-proton (pp), proton-lead (pPb), and peripheral lead-lead (PbPb) collisions are presented as a function of charged particle multiplicity. The pp, pPb and PbPb collision data were collected using the CMS detector at the LHC with a center-of-mass energy per nucleon pair of 13, 8.16 and 5.02 TeV, respectively. The two- and four-particle cumulants for the second- and third-order Fourier anisotropy harmonics are correlated with the mean transverse momentum of charged particles on an event-by-event basis. In pp and pPb systems, the observed correlation coefficients based on two-particle cumulants are found to change from negative to positive values as the charged particle multiplicity decreases. The sign changes disappear when the correlated particles are required to be further apart in pseudorapidity. Additionally, no sign changes in correlation coefficients are observed when employing four-particle cumulants. Models incorporating initial-state gluon saturation and final-state hydrodynamic evolutions are compared to pPb data and the predicted sign changes are not observed. | ||
| Links: e-print arXiv:2410.04578 [hep-ex] (PDF) ; CDS record ; inSPIRE record ; CADI line (restricted) ; | ||
| Figures | |
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Figure 1:
The covariances of cumulants from two- and four-particle correlations and $ [p_{\mathrm{T}}] $ as a function of charged particle multiplicity ($ N_\text{ch} $) in 13 TeV pp (left), 8.16 TeV pPb (middle), and 5.02 TeV PbPb (right) collisions. The two-particle cumulants are obtained with $ |\eta| > $ 0.75. The upper (lower) panels show the second (third) harmonics. The error bars correspond to statistical uncertainties, while the shaded areas denote the systematic uncertainties. |
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Figure 2:
The correlator using two-particle cumulant from $ |\eta| > $ 0.75 and $ |\eta| > $ 1.0 as a function of $ N_\text{ch} $ in 13 TeV pp (left), 8.16 TeV pPb (middle), and 5.02 TeV PbPb (right) collisions. The upper (lower) panels show the second (third) harmonics. The error bars correspond to the statistical uncertainties, and the shaded areas denote the systematic uncertainties. Calculations from PYTHIAviii (upper left panel, red and black lines) and IP-Glasma+MUSIC+UrQMD (middle panels, blue lines) [40] are compared with the data. Hydrodynamic predictions (lower middle panel, red lines) [67] with an average RMS transverse radius of the initial fireball of either 0.9 or 1.5 fm are also included in the comparison. The magenta lines in the middle and right upper panels represent the ATLAS results [41] in pPb and PbPb collisions at 5.02 TeV using $ |\eta| > $ 0.75 with the error bars denoting the statistical and systematic uncertainties added in quadrature. |
| Tables | |
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Table 1:
Average multiplicity of reconstructed tracks per $ N_\mathrm{ch}^\mathrm{rec} $ bin for $ N_\text{ch} $ in this analysis and $ N_\mathrm{trk}^\mathrm{offline} $ in previous CMS measurements [16,19,27] in pp, pPb, and peripheral PbPb collisions. Uncertainties in the tracking efficiency corrected $ N_\text{ch} $ are included. |
| Summary |
| In summary, correlations between mean transverse momentum $ [p_{\mathrm{T}}] $ and multiparticle cumulants from two- and four-particle correlations for Fourier harmonics $ n= $ 2 and $ n= $ 3 are presented in proton-proton (pp) collisions at $ \sqrt{s}= $ 13 TeV, proton-lead (pPb) collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 8.16 TeV and peripheral lead-lead (PbPb) collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV. Sign changes in the modified linear correlators are observed as a function of charged particle multiplicity when using two-particle cumulants with a minimum $ \eta $ gap of 1.5, in the pp and pPb systems. These sign changes disappear when nonflow effects are suppressed using a minimum $ \eta $ gap of 2.0. To further reduce nonflow contribution, four-particle cumulants $ c_2\{4\} $ are also correlated with $ [p_{\mathrm{T}}] $ which shows no sign change in pp and pPb collisions, similar to the two-particle correlation results with a larger $ \eta $ gap. This indicates that after removing nonflow effects, the sign change predicted at low multiplicity by initial-state saturation is not observed. |
| References | ||||
| 1 | PHOBOS Collaboration | System size dependence of cluster properties from two-particle angular correlations in $ \text{CuCu} $ and $ \text{AuAu} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 200 GeV | Phys. Rev. C 81 (2010) 024904 | 0812.1172 |
| 2 | STAR Collaboration | Distributions of charged hadrons associated with high transverse momentum particles in pp and $ \text{AuAu} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 200 GeV | PRL 95 (2005) 152301 | nucl-ex/0501016 |
| 3 | STAR Collaboration | Long-range rapidity correlations and jet production in high energy nuclear collisions | Phys. Rev. C 80 (2009) 064912 | 0909.0191 |
| 4 | PHOBOS Collaboration | High transverse momentum triggered correlations over a large pseudorapidity acceptance in $ \text{AuAu} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 200 GeV | PRL 104 (2010) 062301 | 0903.2811 |
| 5 | CMS Collaboration | Long-range and short-range dihadron angular correlations in central PbPb collisions at a nucleon-nucleon center of mass energy of 2.76 TeV | JHEP 07 (2011) 076 | CMS-HIN-11-001 1105.2438 |
| 6 | ALICE Collaboration | Higher harmonic anisotropic flow measurements of charged particles in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV | PRL 107 (2011) 032301 | 1105.3865 |
| 7 | ALICE Collaboration | Harmonic decomposition of two-particle angular correlations in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV | PLB 708 (2012) 249 | 1109.2501 |
| 8 | CMS Collaboration | Centrality dependence of dihadron correlations and azimuthal anisotropy harmonics in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV | EPJC 72 (2012) 2012 | CMS-HIN-11-006 1201.3158 |
| 9 | ALICE Collaboration | Elliptic flow of charged particles in PbPb collisions at 2.76 TeV | PRL 105 (2010) 252302 | 1011.3914 |
| 10 | ATLAS Collaboration | Measurement of the azimuthal anisotropy for charged particle production in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV lead-lead collisions with the ATLAS detector | Phys. Rev. C 86 (2012) 014907 | 1203.3087 |
| 11 | CMS Collaboration | Measurement of the elliptic anisotropy of charged particles produced in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV | Phys. Rev. C 87 (2013) 014902 | CMS-HIN-10-002 1204.1409 |
| 12 | CMS Collaboration | Overview of high-density QCD studies with the CMS experiment at the LHC | Submitted to Physics Reports, 2024 | CMS-HIN-23-011 2405.10785 |
| 13 | B. H. Alver, C. Gombeaud, M. Luzum, and J.-Y. Ollitrault | Triangular flow in hydrodynamics and transport theory | Phys. Rev. C 82 (2010) 034913 | 1007.5469 |
| 14 | B. Schenke, S. Jeon, and C. Gale | Elliptic and triangular flow in event-by-event (3+1)d viscous hydrodynamics | PRL 106 (2011) 042301 | 1009.3244 |
| 15 | Z. Qiu, C. Shen, and U. Heinz | Hydrodynamic elliptic and triangular flow in PbPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 2.76 TeV | PLB 707 (2012) 151 | 1110.3033 |
| 16 | CMS Collaboration | Observation of long-range near-side angular correlations in proton-proton collisions at the LHC | JHEP 09 (2010) 091 | CMS-QCD-10-002 1009.4122 |
| 17 | ATLAS Collaboration | Observation of long-range elliptic azimuthal anisotropies in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 13 and 2.76 TeV pp collisions with the ATLAS detector | PRL 116 (2016) 172301 | 1509.04776 |
| 18 | CMS Collaboration | Measurement of long-range near-side two-particle angular correlations in pp collisions at $ \sqrt{s} = $ 13 TeV | PRL 116 (2016) 172302 | CMS-FSQ-15-002 1510.03068 |
| 19 | CMS Collaboration | Observation of long-range near-side angular correlations in proton-lead collisions at the LHC | PLB 718 (2013) 795 | CMS-HIN-12-015 1210.5482 |
| 20 | ALICE Collaboration | Long-range angular correlations on the near and away side in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV | PLB 719 (2013) 29 | 1212.2001 |
| 21 | ATLAS Collaboration | Observation of associated near-side and away-side long-range correlations in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV proton-lead collisions with the ATLAS detector | PRL 110 (2013) 182302 | 1212.5198 |
| 22 | LHCb Collaboration | Measurements of long-range near-side angular correlations in $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5 TeV proton-lead collisions in the forward region | PLB 762 (2016) 473 | 1512.00439 |
| 23 | PHENIX Collaboration | Measurements of multiparticle correlations in $ \text{dAu} $ collisions at 200, 62.4, 39, and 19.6 GeV and $ \text{pAu} $ collisions at 200 GeV and implications for collective behavior | PRL 120 (2018) 062302 | 1707.06108 |
| 24 | PHENIX Collaboration | Measurement of long-range angular correlations and azimuthal anisotropies in high-multiplicity $ \text{pAu} $ collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 200 GeV | Phys. Rev. C 95 (2017) 034910 | 1609.02894 |
| 25 | PHENIX Collaboration | Measurements of elliptic and triangular flow in high-multiplicity $ ^{3} $He$ + $Au collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 200 GeV | PRL 115 (2015) 142301 | 1507.06273 |
| 26 | PHENIX Collaboration | Creation of quark-gluon plasma droplets with three distinct geometries | Nature Phys. 15 (2019) 214 | 1805.02973 |
| 27 | 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 |
| 28 | CMS Collaboration | Evidence for collective multiparticle correlations in pPb collisions | PRL 115 (2015) 012301 | CMS-HIN-14-006 1502.05382 |
| 29 | CMS Collaboration | Evidence for collectivity in pp collisions at the LHC | PLB 765 (2017) 193 | CMS-HIN-16-010 1606.06198 |
| 30 | CMS Collaboration | Multiparticle correlation studies in pPb collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 8.16 TeV | Phys. Rev. C 101 (2020) 014912 | CMS-HIN-17-004 1904.11519 |
| 31 | K. Dusling and R. Venugopalan | Evidence for BFKL and saturation dynamics from dihadron spectra at the LHC | PRD 87 (2013) 051502 | 1210.3890 |
| 32 | A. Dumitru and V. Skokov | Anisotropy of the semiclassical gluon field of a large nucleus at high energy | PRD 91 (2015) 074006 | 1411.6630 |
| 33 | B. Schenke, S. Schlichting, and R. Venugopalan | Azimuthal anisotropies in pPb collisions from classical Yang-Mills dynamics | PLB 747 (2015) 76 | 1502.01331 |
| 34 | J. L. Nagle and W. A. Zajc | Small-system collectivity in relativistic hadronic and nuclear collisions | Ann. Rev. Nucl. Part. Sci. 68 (2018) 211 | 1801.03477 |
| 35 | W. Busza, K. Rajagopal, and W. van der Schee | Heavy ion collisions: the big picture, and the big questions | Ann. Rev. Nucl. Part. Sci. 68 (2018) 339 | 1802.04801 |
| 36 | A. Mazeliauskas and D. Teaney | Fluctuations of harmonic and radial flow in heavy ion collisions with principal components | Phys. Rev. C 93 (2016) 024913 | 1509.07492 |
| 37 | P. Bozek | Transverse-momentum-flow correlations in relativistic heavy ion collisions | Phys. Rev. C 93 (2016) 044908 | 1601.04513 |
| 38 | B. Schenke, C. Shen, and D. Teaney | Transverse momentum fluctuations and their correlation with elliptic flow in nuclear collisions | Phys. Rev. C 102 (2020) 034905 | 2004.00690 |
| 39 | G. Giacalone, F. G. Gardim, J. Noronha-Hostler, and J.-Y. Ollitrault | Correlation between mean transverse momentum and anisotropic flow in heavy ion collisions | Phys. Rev. C 103 (2021) 024909 | 2004.01765 |
| 40 | G. Giacalone, B. Schenke, and C. Shen | Observable signatures of initial-state momentum anisotropies in nuclear collisions | PRL 125 (2020) 192301 | 2006.15721 |
| 41 | ATLAS Collaboration | Measurement of flow harmonics correlations with mean transverse momentum in lead-lead and proton-lead collisions at $ \sqrt{\smash[b]{s_{_{\mathrm{NN}}}}} = $ 5.02 TeV with the ATLAS detector | EPJC 79 (2019) 985 | 1907.05176 |
| 42 | C. Zhang, A. Behera, S. Bhatta, and J. Jia | Nonflow effects in correlation between harmonic flow and transverse momentum in nuclear collisions | PLB 822 (2021) 136702 | 2102.05200 |
| 43 | S. H. Lim and J. L. Nagle | Exploring origins for correlations between flow harmonics and transverse momentum in small collision systems | Phys. Rev. C 103 (2021) 064906 | 2103.01348 |
| 44 | CMS Collaboration | HEPData record for this analysis | link | |
| 45 | CMS Collaboration | The CMS experiment at the CERN LHC | JINST 3 (2008) S08004 | |
| 46 | CMS Collaboration | Development of the CMS detector for the CERN LHC Run 3 | CMS-PRF-21-001 2309.05466 |
|
| 47 | 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 |
| 48 | 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 |
| 49 | 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 |
| 50 | CMS Collaboration | Particle-flow reconstruction and global event description with the CMS detector | JINST 12 (2017) P10003 | CMS-PRF-14-001 1706.04965 |
| 51 | Tracker Group of the CMS Collaboration | The CMS phase-1 pixel detector upgrade | JINST 16 (2021) P02027 | 2012.14304 |
| 52 | CMS Collaboration | Track impact parameter resolution for the full pseudo rapidity coverage in the 2017 dataset with the CMS phase-1 pixel detector | CMS Detector Performance Note CMS-DP-2020-049, 2020 CDS |
|
| 53 | 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 |
| 54 | CMS Collaboration | The CMS trigger system | JINST 12 (2017) P01020 | CMS-TRG-12-001 1609.02366 |
| 55 | CMS Collaboration | CMS luminosity measurement for the 2018 data-taking period at $ \sqrt{s}= $ 13 TeV | CMS Physics Analysis Summary, 2019 CMS-PAS-LUM-18-002 |
CMS-PAS-LUM-18-002 |
| 56 | CMS Collaboration | CMS luminosity measurement using 2016 proton-nucleus collisions at $ {\sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 8.16 TeV | CMS Physics Analysis Summary, 2018 CMS-PAS-LUM-17-002 |
CMS-PAS-LUM-17-002 |
| 57 | CMS Collaboration | CMS luminosity measurement using nucleus-nucleus collisions at $ {\sqrt{\smash[b]{s_{_{\mathrm{NN}}}}}= $ 5.02 TeV in 2018 | CMS Physics Analysis Summary, 2022 CMS-PAS-LUM-18-001 |
CMS-PAS-LUM-18-001 |
| 58 | 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 |
| 59 | T. Sjöstrand et al. | An introduction to PYTHIA 8.2 | Comput. Phys. Commun. 191 (2015) 159 | 1410.3012 |
| 60 | 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 |
| 61 | M. Gyulassy and X.-N. Wang | HIJING 1.0: A Monte Carlo program for parton and particle production in high-energy hadronic and nuclear collisions | Comput. Phys. Commun. 83 (1994) 307 | nucl-th/9502021 |
| 62 | 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 |
| 63 | GEANT4 Collaboration | GEANT 4---a simulation toolkit | Nucl. Instrum. and Meth. A 506 (2003) 250 | |
| 64 | ALICE Collaboration | Characterizing the initial conditions of heavy-ion collisions at the LHC with mean transverse momentum and anisotropic flow correlations | PLB 834 (2022) 137393 | 2111.06106 |
| 65 | A. Bilandzic, R. Snellings, and S. Voloshin | Flow analysis with cumulants: Direct calculations | Phys. Rev. C 83 (2011) 044913 | 1010.0233 |
| 66 | J. Jia, M. Zhou, and A. Trzupek | Revealing long-range multiparticle collectivity in small collision systems via subevent cumulants | Phys. Rev. C 96 (2017) 034906 | 1701.03830 |
| 67 | P. Bozek and H. Mehrabpour | Correlation coefficient between harmonic flow and transverse momentum in heavy ion collisions | Phys. Rev. C 101 (2020) 064902 | 2002.08832 |
| 68 | A. Bzdak, B. Schenke, P. Tribedy, and R. Venugopalan | Initial state geometry and the role of hydrodynamics in proton-proton, proton-nucleus and deuteron-nucleus collisions | Phys. Rev. C 87 (2013) 064906 | 1304.3403 |
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