Measurements of heavyflavour correlations and elliptic flow with

Measurements of heavy-flavour correlations and elliptic flow with ALICE Henrique Zanoli on behalf of the ALICE Collaboration University of São Paulo (Brazil) and Utrecht University (Netherlands) H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE

• Pb-Pb collisions: • The Quark-Gluon Plasma • Azimuthal anisotropy • Heavy-flavour particles as probes of the QGP • D-meson anisotropic flow • Event-shape engineering for the D-meson v 2 • p-Pb collisions: • The double-ridge • Azimuthal anisotropy of HF electrons Contents H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 2

Pb-Pb collisions H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 3

Quark-Gluon Plasma • Present in the first few moments of the universe. • Produced in heavy-ion (Pb-Pb) collisions ar. Xiv: 0809. 3137 H. Zanoli LISHEP 2018 • Quarks and gluons are non-longer confined to the atomic nuclei. Relevant to understand QCD Phase Diagram. HF correlations and elliptic flow with ALICE 4

QGP properties: With QGP No QGP Jet suppression and energy loss Particles lose energy when traveling in the QGP H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 5

QGP properties: Azimuthal anisotropy 49. 29 9 0 08 : v i ar. X Spatial anisotropy (geometry) Non-central collision QGP Pressure gradients Momentum anisotropy Soft sector (low p. T): multiple interactions between partons (collectivity) H. Zanoli LISHEP 2018 Hard sector (high p. T): path-length dependent energy loss HF correlations and elliptic flow with ALICE 6

Measuring the azimuthal anisotropy • Measure the correlations of two, or more particles Ridge coming from elliptic flow Range of techniques to suppress contributions from jets, decays, etc (“non-flow”) H. Zanoli LISHEP 2018 Away-side jet + elliptic flow Near-side jet Phys. Lett. B 724 (2013) 213 HF correlations and elliptic flow with ALICE 7

Heavy-quarks: probing the system evolution • High mass: produced in hard scatterings, on a short time scale • Propagate through the medium interacting with its constituents. Questions • Transport properties of the medium Information provided • Parton energy-loss mechanisms by heavy quarks • Hadronization mechanisms • Is heavy-quark elliptic flow non-zero? Is it similar to that of light-flavour particles? • How does the c/b quark couples with the bulk of light quarks? H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 8

ALICE detector EMCAL: e PID and trigger |η| < 0. 7 ITS: vertexing and tracking |η| < 0. 9 TPC: tracking and PID |η| < 0. 9 TOF: PID |η| < 0. 9 H. Zanoli LISHEP 2018 V 0 and ZDC: trigger and multiplicity/centrality determination HF correlations and elliptic flow with ALICE 9

D-mesons reconstruction π+ π+ • Fully reconstructed in hadronic decays • Topological selection of secondary vertexes and invariant mass analysis Secondary vertex D+ Primary vertex K– Mass (Ge. V/c 2) Decay BR (%) D 0 1. 865 123 K– π+ 3. 93 D+ 1. 870 312 K– π+ π+ 9. 46 D*+ 2. 010 - D 0 (K– π+) π+ 67. 7 x 3. 93 Ds+ 1. 968 150 Φ(K– K+ ) π+ 2. 27 H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 10

Heavy-flavour decay electron (HFe) identification e± D X Semi leptonic decays of mesons and baryons with c and b quarks νe Particle identification: TPC energy loss, time of flight (TOF), electromagnetic calorimeter Dalitz decay of neutral mesons and γ conversions identified via invariant mass of electron pairs and subtracted H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 11

D-meson v 2 • First measurement of the strange D meson in v 2 at the LHC. Significance of positive v 2 of 2. 6σ for 2 < p. T < 8 Ge. V/c • Average non-strange D-meson v 2 larger than zero in 2 < p. T < 10 Ge. V/c • Strange and non strange D mesons are compatible within uncertainties. Phys. Rev. Lett. 120, 102301 H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 12

D-meson v 2 • Phys. Rev. Lett. 120, 102301 H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 13

Event-shape engineering (ESE) with the reduced flow vector: How does the c quark couples with the bulk of light quarks? High q 2 “Elliptic-like” interaction area Low q 2 Study one observable in classes of events corresponding to the same centrality, but different eccentricity H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE More circular interaction area 14

How does the c quark couples with the bulk of light quarks? Selecting events with different eccentricity H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 15

D-meson v 2 with event shape engineering H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 16

D-meson v 2 with event shape engineering D-meson v 2 about 50% (30%) larger than the unbiased one in the large(small)-q 2 sample D mesons are sensitive to the lightquark collectivity and event-by-event fluctuations in initial conditions H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 17

p-Pb collisions H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 18

The double ridge p-Pb Pb-Pb Phys. Lett. B 724 (2013) 213 Phys. Lett. B 726 (2013) 164– 177 • Two-particle correlation functions in p-Pb (and pp) collisions have a similar ridge as in Pb-Pb Phenomena first seem at the LHC H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 19

v 2 extraction - = • Jet contribution subtraction using low multiplicity collisions and/or pp collisions • Modulation quantified by its Fourier coefficients H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 20

Pb-Pb vs p-Pb JHEP 06 (2015) 190 Similar mass dependence in Pb-Pb and p-Pb collisions H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 21

v 2 of light-flavour hadrons in p-Pb • Mass dependence at low momentum • Baryon/meson grouping at intermediate momentum • Origin still on debate regarding the hydrodynamics and geometry fluctuations • Collective effects? Medium formation? H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 22

What about heavy-flavor particles? Do they have azimuthal anisotropy as in Pb-Pb? H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 23

HFe v 2 at high multiplicity p-Pb • Two-particle correlations between HFe with charged particles in high-multiplicity and low-multiplicity events • Near and away side modification from low multiplicity to high multiplicity Modification H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 24

Pions HF electrons Similar effect present in pion-hadron and HF electrons - hadron correlations H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 25

Quantifying the modulation • Jet subtraction: high mult. - low mult. -> remove most of shortrange correlations • Modulation present! Quantify its strength by the v 2 H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 26

HFe v 2 at high multiplicity • Effect is qualitatively similar to the one observed for light flavours and inclusive muons • Significance: 5. 1σ for 1. 5< p. Te< 4 Ge. V/c ar. Xiv: 1805. 04367 H. Zanoli LISHEP 2018 Initial- or final-state effect? HF correlations and elliptic flow with ALICE 27

Summary • In Pb-Pb collisions: studying properties of the QGP • The spatial anisotropy of the Quark-Gluon Plasma generates momentum anisotropy on the final particles. We have found positive v 2 (elliptic flow) for both light- and heavy-flavour particles. • Studies using event-shape engineering show that the elliptic flow of D mesons is sensitive to the collectivity of the bulk of light-flavoured particles generated in the collisions and to initial condition fluctuations • In p-Pb collisions: understanding an unexpected result • Positive v 2 for both light-flavour and heavy-flavour particles, similar features for p-Pb and Pb-Pb collisions H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 28

Thank you! Acknowledgement H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 29

Backup H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 30

Heavy-flavour electron elliptic flow • At high momentum, the measurement should be dominated by electrons from beauty hadron decays • Significant non-zero v 2 measured for HF electrons • Complementary to D-meson studies H. Zanoli LISHEP 2018 HF correlations and elliptic flow with ALICE 31