Istituto Nazionale di Fisica Nucleare LNF Frascati May

Istituto Nazionale di Fisica Nucleare –LNF, Frascati. May , 2018 Physics at forward-rapidity in heavyion collisions Xin-Nian Wang CCNU/LBNL 1

Three properties of s. QGP • The most perfect fluid ( h/s ~ (1 - 2)/4 p ) • The most opaque fluid to jets ( qhat/T 3 =4 - 8) • The most vortical fluid (w/T ~ 0. 001) 2

Relativistic hydrodynamics – a low-momentum effective theory – Inputs from first principle QCD (e. g. lattice QCD) Eo. S p=p(e), transport coefficients h(T), z(T) – Initial condition: parton prod. & thermalization time 3

CLVisc Hydrodynamic model • 3+1 D viscous hydrodynamic model • Fully parallelized on GPU with Open. CL – 100 x faster than comparable than on CPU • Fluctuating initial conditions from AMPT Pang, Petersen, XNW, ar. Xiv: 1802. 04449 4

Sounds of QGP Propagation of primordial sound waves in a rapidly expanding fireball sensitivity to viscosity and initial conditions L Pang（2016） These collective effects will be mirrored in the final hadron spectra 5

Transverse anisotropic flows hv/s=0. 15 Pang, Petersen & XNW, ar. Xiv: 1802. 04449 6

3+1 D Hydrodynamics with 3 D fluctuating initial conditions y h x x Longitudinal structure of fluctuation and anisotropic flows 7

Rapidity dependence of vn Consistent with the longitudinal dependence of the initial energy density and pressure Pang, Petersen & XNW, ar. Xiv: 1802. 04449 8

Longitudinal decorrelation of vn Fluctuation and twist of the event plane Pang, Qin, Roy, XNW, Ma, Phys. Rev. C 91 (2015) 044904 Pang, Petersen, Qin, Roy & XNW EPJA 52(2006) 97

Fluctuation versus rotation Wu, Pang, Qin & XNW ar. Xiv: 1805. 03762 v 1 Decorrelation due to amplitude fluctuation is smaller versus event-plane rotation 10

Global Orbital Angular Momentum Heavy ion collisions: y z Local vorticity x

Global spin polarization in A+A Liang & XNW, PRL 94 (2005) 102301 spin-vorticity coupling Bjorken scaling violation

Spin polarization in equilibrium Dirac Eq. Spin: vorticity coupling Magnetic coupling + gradient expansion Becattini & Ferroni, EJPC 52 (2007) 597, Betz, Gyulassy & Torrieri, PRC 76 (2007) 044901, Becattini, Piccinini & Rizzo, PRC 77 (2008) 024906, Beccatini, Csernai & Wang, PRC 87 (2013) 034905, Xie, Glastad & Csernai, PRC 92 (2015) 064901, Deng & Huang, ar. Xiv 1603. 06117

Consequences in A+A collisions Globally Polarized thermal dilepton, J/Y, Hyperons and vector mesons Constituent quark model Yang, Fang, Wang & XNW ar. Xiv: 1711. 06008 Liang & XNW, PRL 94 (05) 102301 Liang & XNW, PLB 629(05)20 Gao et al, PRC 77 (08) 044902

Features of Global Hyperon Polarization • • Hyperons & anti-hyperons are similarly polarized PH=0 in central and increases with b Increases with y at fixed collision energy Increase at lower energy at fixed y y

Transverse vorticity: Toroidal structure x Toroidal structure of transverse fluid vorticity, in addition to the global net vorticity Pang, Petersen, Wang & XNW, PRL 117(2016) 192301

Transverse spin correlation Pb + Pb @ 2. 76 Te. V (20 -30%) Pang, Petersen, Wang & XNW, PRL 117(2016) 192301

Summary: I • QGP in heavy-ion collisions has interesting longitudinal structure at large rapidity • Fluctuations in longitudinal direction leads to decorrelation of anisotropic flow and rotation event planes • BJ scaling violation leads to larger local vorticity large lambda polarization • 18

Jet quenching in heavy-ion collisions Parton energy loss leads to jet suppression Jet 1 q q Jet 2 Energy deposition leads to medium excitation 19

Jet Quenching phenomena at RHIC Pedestal&flow subtracted STAR Preliminary

Jet Quenching phenomena at LHC Pedestal&flow subtracted

Jet transport coefficient JET Collaboration: Phys. Rev. C 90 (2014) 1, 014909 22

Tomography with full jets Jet profile and jet yield sensitive to jet-medium interaction Less sensitive to non-perturbative hadronization Jet-induced medium excitation becomes relevant 23

LBT: Linear Boltzmann Transport Induced radiation • p. QCD elastic and radiative processes (high-twist) • Transport of medium recoil partons • 3+1 D hydro bulk evolution jet parton medium parton Li, Liu, Ma, XNW and Zhu, PRL 106 （2010） 012301 XNW and Zhu, PRL 111 (2013) 062301 He, Luo, XNW & Zhu, PRC 91 (2015) 054908;

Beyond LBT: Co. LBT-hydro (Coupled Linear Boltzmann Transport hydro) • LBT for energetic partons (jet shower and recoil) • Hydrodynamic model for bulk and soft partons: CLVisc: (3+1)D viscous hydrodynamics parallelized on GPU using Open. CL Hadronization in LBT: TAMU parton recombination model 25

g-jet propagation within Co. LBT-hydro 26

Light and heavy quark hadron suppression Au. Au@200 Pb. Pb@5020 Pb. Pb@2760 Ge. V Cao, Luo, Qin & XNW, PRC 94 (2016) 014909 27

Medium response & jet energy loss 0 -10% 2. 76 Te. V preliminary R=0. 4 Recoil partons within the jet cone reduce the net jet energy loss Diffusion wake (backreaction) reduces deplete thermal background, if taken into account, increase the net jet Energy loss with given conesize Depend on jet cone-size R Sensitive to radial flow 28

Single jet suppression at LHC LBT: preliminary Weak p. T dependence: initial jet spectra and p. T dependence of energy loss DE Week energy dependence: increase of jet energy loss and the slope of initial spectra 29

Energy dependence of jet quenching 30

Jet energy loss and g-jet asymmetry Luo, Cao, He & XNW, ar. Xiv: 1803. 06785 Poster: JET 18 T Luo 31

Z-jet quenching in Pb+Pb collisions ar. Xiv: 1804. 11041 32

Gamma-jet profile Pb+Pb @ 2. 76 Te. V p+p @ 2. 76 Te. V preliminary 33

gamma-jet fragmentation function Preliminary Co. LBT-hydro CMS R=0. 3 34

Enhancement of soft hadrons PLB 777(2018)86 Onset of soft hadron enhancement is at fixed pt ~ 1. 6 Ge. V 35

Azimuthal distribution of soft hadrons from jet-induced medium excitation PLB 777(2018)86 36

Correlation btw jet and bulk anisotropy 37

Longitudinal structure of QGP 38

Nuclear Modification of PDF Large uncertainty in gluon distribution in large nuclear 39

Flavor dependence of nuclear PDF Kulagin & Petti (KP) parameterization 40

W charge asymmetry h of decay lepton 41

Rapidity dependence of jet quenching 42

Summary: II • QGP in heavy-ion collisions has interesting longitudinal structure • Fluctuations in longitudinal direction leads to decorrelation of anisotropic flow and rotation event planes • BJ scaling violation leads to larger local vorticity large lambda polarization • Jet quenching at large rapidity probes QGP in the forward direction • A lot of physics opportunities in the forward direction for experiments such as LHCb 43