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The Fifth Annual Conference on Large Hadron Collider Physics May 15-20, 2017, Shanghai, China Collectivity in proton-proton, proton-nucleus and nucleusnucleus collisions Tetsufumi Hirano Sophia Univ. The Fifth Annual Conference on Large Hadron Collider Physics May 15-20, 2017, Shanghai, China Highlights of theoretical topics on collective flow at LHC energy Tetsufumi Hirano Sophia Univ. Introduction β’ Limited time as for review talk (15 min.!) β’ Discussion about new ideas beyond conventional hydrodynamic analysis β’ More various aspects of flow phenomena Three topics covered in this talk 1. Hydrodynamic fluctuations 2. Medium response to jet propagation 3. Dynamical initialization of QGP 1. Hydrodynamic fluctuations Entropy Fluctuation-dissipation relations Thermal equilibrium state dissipation Conventional viscous hydro ο Dissipation only fluctuation π = π0 + πΏπ + πΏ 2 π + β― <0 State Fluctuating hydro as a next generation of dynamical model See also, Calzetta (1997), Kapusta, Muller, Stephanov (2012), Murase, TH (2013), Moore, Kovtun, Romatschke (2014), Young, Gale, Jeon, Schenke (2015), Yan, Grönqvist (2016), β¦ Event-by-event shear stress tensor Fluctuating hydro Viscous hydro ππ π π₯ = 2ππ π π’π + ππ πΏπ π₯ πΏπ ππ πΏπ ππ ~4ππ/π: F-D relation β― : Ensemble average N.B.) Relaxation term in actual simulations for causality Movie: Courtesy of K. Murase Third generation hydro code Test simulation: QGP in a box Viscous hydro Fluctuating hydro Ideal hydro (2G hydro) (1G hydro) (3G hydro) No dissipation Wave propagation Towards global equilibrium Fluctuation around mean value π Factorization ratio π2 π , π 3.0 < ππ < 4.0 A.Sakai, talk at QM2017 π Full 3D fluctuating hydro + hadronic afterburner available! Effects of hydrodynamic fluctuations ο Two point correlation function in momentum space Ideal hydro β Visc. hydro > Exp. data > Fluc. hydro A new constraint on transport properties of QGP 2. Medium response to jet propagation QGP fluid + jet model ππ ππ πfluid Evolution of QGP fluid = π½π Energy momentum deposition Y.Tachibana, talk at QM2017 See also, Stocker et al. (2005), Casalderrey-Sonala et al. (2005), Chaudhuri et al. (2006), Betz et al. (2009), Qin et al. (2009), Neufeld et al. (2010), Tachibana, TH (2014), Andrade et al. (2014), Schulc et al. (2014), He et al. (2015), Tachibana et al (2017), β¦ Transport eq. in jet shower Energy-momentum dist. in jet shower ππ Collisional energy loss Momentum broadening Deposited to QGP fluids Radiative energy loss N.B.Chang and G.-Y. Qin (2016) Cutting edge source terms in QGP fluid + jet model Y.Tachibana, talk at QM2017 Transport of lost energy Y.Tachibana et al. (2017) Large angle emission (π > 0.3) of soft particles from jet axis (CMS) ο Interplay btw. soft and hard ο Medium response required at large angle Jet structure at large π: A new channel to constrain transport properties of QGP? 3. Dynamical initialization of QGP Conventional hydro New approach Parametrization or modelling at π = π0 π π0 , π₯, π¦, ππ , π’π (π0 , π₯, π¦, πs ) ππ πfluid π = π00 , π₯, π¦, πs = 0 ππ πππ π½π π (π, π₯, π¦, πs ) = ππ πfluid π = π0 , π₯, π¦, πs Cons: How to parametrize random flow velocity? π Modeling of π½π locally ππ πfluid π = π0 , π₯, π‘, πs See also, Okai, Kawaguchi, Tachibana, TH (2017), Shen (2017), Lin (2017) Dynamical initialization from mini-jets π From mini-jet to QGP π πππ π π½π π₯ = β πΏ ππ‘ 3 π β ππ ππ , π‘ Time of πmax differs from point to point M.Okai, et al. (2017) Initial profile of energy density and flow velocity π = 0.6 fm π¦ (fm) π₯ (fm) Fluctuating profile + random transverse flow ο Consequence of momentum conservation ο Effects can be seen in observables? M.Okai, et al. (2017) Event-plane decorrelation from random transverse flow M.Okai, et al. (2017) Low πT : Correlation with initial eccentricity Intermediate πT : Decorrelation with event plane due to initial random transverse flow ο π£2 πT saturates in intermediate πT even w.o. viscosity Factorization ratio? Probe to investigate initial stage? Small system? Summary Three topics 1. Hydrodynamic fluctuations 2. Medium response to jet propagation 3. Dynamical initialization of QGP β’ Would be important in near future in understanding collective flow under precise and comprehensive measurements at LHC. β’ Serve as new tools to constrain transport properties and to interpret intriguing phenomena. Event plane fluctuations and decorrelations Event plane angle Ξ¦π π Ξ¦ π = const.or not? Factorization breaking down Figure taken from J. Jia, and P. Huo, Phys. Rev. C 90, 034905 (2014) ππΞ β π£ππ π£ππ ππpair β1+2 πΞπ ππΞ cos πΞπ ο Event plane fluctuations/decorrelations Factorization ratio ππ ππ , ππ ππΞ βππ , ππ = , ππΞ = cos πΞπ π π ππΞ π , π Purpose of study: Effects of hydrodynamic fluctuations on factorization ratios 17 CMS Collaboration, Phys. Rev. C 92, 034911 (2015)
