COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 1 EPOS Klaus Werner with Tanguy Pierog, Karlsruhe, Germany Yuriy Karpenko, Nantes, France Benjamin Guiot, Valparaiso, Chile Gabriel Sophys, Nantes, France Maria Stefaniak, Nantes & Warsaw, Poland Mahbobeh Jafarpour, Nantes, France Johannès Jahan, Nantes, France
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 2 Contents 1 Introduction 4 2 Glauber and Gribov-Regge approach 32 3 Collectivity 60 4 Summary 84
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 3 Todays lecture: short version of a detailed lecture (266 pages) at the Joliot-Curie International School 2018 https://ejc2018.sciencesconf.org/data/pages/joliot.20.pdf Today only some selected (important) topics ...
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 4 ————————————————————— Introduction 1 —————————————————————
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 5 EPOS is an event generator to treat consistently � e+e- annihilation (test string fragmentation) � ep scattering (test parton evolution) � pp, pA, AA collisions at high energies (collision finished before particle production starts)
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 6 Basic structure of EPOS (for modelling pp, pA, AA) � Primary interactions Multiple scattering, instantaneously, in parallel (Parton Based Gribov-Regge Theory) – in pA and AA: multiple NN scattering – but also in pp : Multiple parton scattering (or for each NN scattering in pA, AA) � Secondary interactions formation of “matter” which expands collectively, like a fluid, decays statistically
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 7 Some history of Gribov-Regge Theory (the heart of EPOS) � 1960-1970: Gribov-Regge Theory of multiple scattering. pp = multiple exchange of “Pomerons” (with amplitudes based on Regge poles) � 1980-1990: pQCD processes added into GRT scheme (Capella) � 1990: M.Braun, V.A.Abramovskii, G.G.Leptoukh: problem with energy conservation (not done consistently)
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 8 � 2001: H.J.Drescher, M.Hladik, S.Ostapchenko, T. Pierog, and K. Werner, Phys. Rept. 350, p93: Marriage pQCD + GRT, with energy sharing (NEXUS) Multiple scatterings (in parallel !!) + + x x 1 in pp, pA, or AA 2 Single scattering − x − x 1 = hard elementary 2 scattering including IS + FS ✎ ☞ radiation ∑ x ± i + x ± remn = 1 ✍ ✌
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 9 � ~ 2003 NEXUS split into � QGSJET (S. Ostapchenko) – Triple Pomeron contributions and more, to all orders � EPOS (T. Pierog, KW) – Saturation scale, secondary interactions – two versions, EPOSLHC and EPOS3, going to be “fused”, with a rigorous (selfconsistent) treatment of new key features (HF, saturation & factorization) => new public version ( β version exists since few days ...) Two of the key models used for airshower simulations
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 10 Secondary interactions: Example: space-time evolution in pp leading to collective flow
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 11 3 η τ energy density [GeV/fm ] ( = 0.0 , = 0.10 fm/c) J 0 s 350 pp @ 7TeV EPOS 3.119 y [fm] 2 1.5 300 1 250 0.5 200 0 150 -0.5 100 -1 50 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 12 3 η τ energy density [GeV/fm ] ( = 0.0 , = 0.29 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 60 1.5 1 50 0.5 40 0 30 -0.5 20 -1 10 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 13 3 η τ energy density [GeV/fm ] ( = 0.0 , = 0.48 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 1.5 20 1 15 0.5 0 10 -0.5 -1 5 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 14 3 η τ energy density [GeV/fm ] ( = 0.0 , = 0.68 fm/c) J 0 s 9 pp @ 7TeV EPOS 3.119 y [fm] 2 8 1.5 7 1 6 0.5 5 0 4 -0.5 3 -1 2 1 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 15 3 η τ energy density [GeV/fm ] ( = 0.0 , = 0.87 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 1.5 4 1 3 0.5 0 2 -0.5 -1 1 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 16 3 η τ energy density [GeV/fm ] ( = 0.0 , = 1.06 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 2.5 1.5 2 1 0.5 1.5 0 1 -0.5 -1 0.5 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 17 3 η τ energy density [GeV/fm ] ( = 0.0 , = 1.25 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 1.4 1.5 1.2 1 1 0.5 0.8 0 0.6 -0.5 0.4 -1 0.2 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 18 3 η τ energy density [GeV/fm ] ( = 0.0 , = 1.44 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 0.9 1.5 0.8 0.7 1 0.6 0.5 0.5 0 0.4 -0.5 0.3 -1 0.2 0.1 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 19 3 η τ energy density [GeV/fm ] ( = 0.0 , = 1.63 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 0.6 1.5 0.5 1 0.4 0.5 0 0.3 -0.5 0.2 -1 0.1 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 20 3 η τ energy density [GeV/fm ] ( = 0.0 , = 1.83 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 0.45 1.5 0.4 0.35 1 0.3 0.5 0.25 0 0.2 -0.5 0.15 -1 0.1 0.05 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 21 3 η τ energy density [GeV/fm ] ( = 0.0 , = 2.02 fm/c) J 0 s 0.35 pp @ 7TeV EPOS 3.119 y [fm] 2 1.5 0.3 1 0.25 0.5 0.2 0 0.15 -0.5 0.1 -1 0.05 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 22 3 η τ energy density [GeV/fm ] ( = 0.0 , = 2.21 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 0.25 1.5 0.2 1 0.5 0.15 0 0.1 -0.5 -1 0.05 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 23 3 η τ energy density [GeV/fm ] ( = 0.0 , = 2.40 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 0.2 1.5 1 0.15 0.5 0 0.1 -0.5 0.05 -1 -1.5 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 24 3 η τ energy density [GeV/fm ] ( = 0.0 , = 2.59 fm/c) J 0 s pp @ 7TeV EPOS 3.119 y [fm] 2 0.16 1.5 0.14 1 0.12 0.5 0.1 0 0.08 -0.5 0.06 -1 0.04 -1.5 0.02 0 -2 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 x [fm]
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 25 Radial flow visible in particle distributions Particle spectra affected by radial flow 10 2 _ dn/dptdy π - K - p Λ hydrodynamics (solid) 10 string decay (dotted) 1 -1 10 -2 10 0 1 2 3 pt => mass ordering of � p t � , lambda/K increase
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 26 pPb at 5TeV CMS,EPJC 74 (2014) 2847, arXiv:1307.3442 dn/dptdy dn/dptdy 4 K EPOS3.074 p EPOS3.074 3.5 CMS CMS 3.5 3 3 2.5 2.5 2 2 1.5 1.5 1 1 0.5 0.5 0 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 pt pt Strong variation of shape with multiplicity for kaon and even more for proton pt spectra (EPOS curves: flow changes shapes)
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 27 Anisotropic radial flow visible in dihadron-correlations 1 dn R = d ∆ φ ∆ η N trigg Anisotropic flow due to initial azimuthal anisotropies
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 28 Initial “elliptical” matter distribution: Preferred expansion φ along φ = 0 and φ = π η s -invariance same form at any η s η s = 1 2 ln t + z t − z
COST WS Lund University # February 2019 # Klaus Werner # Subatech, Nantes 29 ∝ 1 + 2 v 2 cos ( 2 φ ) f( φ ) = dn / d φ 0.2 Particle 0.15 distribution: 0.1 Preferred directions 0.05 φ = 0 and φ = π 0 -1 0 1 2 3 4 φ Dihadrons: preferred ∆ φ = 0 and ∆ φ = π (even for big ∆ η )
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