Summary of CPOD 2017 (Critical) comments and personal observations M. Stephanov M. Stephanov Summary CPOD 2017 1 / 1
Blanket apology for talks uncovered M. Stephanov Summary CPOD 2017 2 / 1
History Cagniard de la Tour (1822): discovered continuos transition from liquid to vapour by heating alcohol, water, etc. in a gun barrel, glass tubes. M. Stephanov Summary CPOD 2017 3 / 1
Name Faraday (1844) – liquefying gases: “Cagniard de la Tour made an experiment some years ago which gave me occasion to want a new word.” Mendeleev (1860) – measured vanishing of liquid-vapour surface tension: “Absolute boiling temperature”. Andrews (1869) – systematic studies of many substances established continuity of vapour-liquid phases. Coined the name “critical point”. M. Stephanov Summary CPOD 2017 4 / 1
Theory van der Waals (1879) – in “On the continuity of the gas and liquid state” (PhD thesis) wrote e.o.s. with a critical point. Smoluchowski, Einstein (1908,1910) – explained critical opalescence. Landau – classical theory of critical phenomena Fisher, Kadanoff, Wilson – scaling, full fluctuation theory based on RG. M. Stephanov Summary CPOD 2017 5 / 1
Critical point is a ubiquitous phenomenon M. Stephanov Summary CPOD 2017 6 / 1
Critical point between the QGP and hadron gas phases? QCD is a relativistic theory of a fundamental force. CP is a singularity of EOS, anchors the 1st order transition. QGP (liquid) critical point ? Quarkyonic regime hadron gas nuclear CFL+ ? matter M. Stephanov Summary CPOD 2017 7 / 1
Critical point between the QGP and hadron gas phases? QCD is a relativistic theory of a fundamental force. CP is a singularity of EOS, anchors the 1st order transition. QGP (liquid) critical point ? Quarkyonic regime hadron gas nuclear CFL+ ? matter Lattice QCD at µ B � 2 T – a crossover. C.P . is ubiquitous in models (NJL, RM, Holog., Strong coupl. LQCD, . . . ) M. Stephanov Summary CPOD 2017 7 / 1
Essentially two approaches to discovering the QCD critical point. Each with its own challenges. Lattice simulations. 200 LTE04 LTE03 T , LTE08 The sign problem restricts reliable lat- LR01 MeV LR04 150 tice calculations to µ B = 0 . 100 Under different assumptions one can estimate the position of the critical point, assuming it exists, by extrapo- 50 lation from µ = 0 . 0 0 200 400 600 800 µ B , MeV Heavy-ion collisions. M. Stephanov Summary CPOD 2017 8 / 1
Essentially two approaches to discovering the QCD critical point. Each with its own challenges. Lattice simulations. 200 130 LTE04 LTE03 T , LTE08 The sign problem restricts reliable lat- LR01 17 MeV LR04 150 9 tice calculations to µ B = 0 . 5 100 Under different assumptions one can estimate the position of the critical point, assuming it exists, by extrapo- 50 2 lation from µ = 0 . 0 0 200 400 600 800 µ B , MeV Heavy-ion collisions. M. Stephanov Summary CPOD 2017 8 / 1
Essentially two approaches to discovering the QCD critical point. Each with its own challenges. Lattice simulations. 200 130 LTE04 LTE03 T , LTE08 The sign problem restricts reliable lat- LR01 17 MeV LR04 150 R H I 9 C tice calculations to µ B = 0 . s c a n 5 100 Under different assumptions one can estimate the position of the critical point, assuming it exists, by extrapo- 50 2 lation from µ = 0 . 0 0 200 400 600 800 µ B , MeV Heavy-ion collisions. M. Stephanov Summary CPOD 2017 8 / 1
Essentially two approaches to discovering the QCD critical point. Each with its own challenges. Lattice simulations. 200 130 LTE04 LTE03 T , LTE08 The sign problem restricts reliable lat- LR01 17 MeV LR04 150 R H I 9 C tice calculations to µ B = 0 . s c a n 5 100 Under different assumptions one can estimate the position of the critical point, assuming it exists, by extrapo- 50 2 lation from µ = 0 . 0 0 200 400 600 800 µ B , MeV Heavy-ion collisions. Non-equilibrium. M. Stephanov Summary CPOD 2017 8 / 1
Connecting theory and experiment Develop EOS with critical point which also matches available lat- tice data Parotto Implement it into a realistic hydro simulation Shen, Yin, Song, Pratt, . . . Compare with experiments to constrain parameters of the critical point: position, non-universal amplitudes, angles, etc. Auvinen Develop theory of the CME in heavy-ion collisions and embed in MHD Schlichting, Hirono, Shi . . . Compare with experiments. Isobaric run in 2018! Wen Vorticity and polarization. Upsal, Wang M. Stephanov Summary CPOD 2017 9 / 1
Lattice Schmidt Ratios of Taylor coeffs. are estimators of the radius of conver- gence. Cannot predict, or exclude , C.P . without assumptions about asymptotics . M. Stephanov Summary CPOD 2017 10 / 1
Lattice Schmidt Critical point is not always the nearest singularity. E.g.: The convergence radius at T c for m q = 0 is zero (hep-lat/0603014). M. Stephanov Summary CPOD 2017 11 / 1
Sum m a ry Guenther ( WB collaboration ) 300 V) ) V) V) V) V S/N B = 51 (19.6 Ge S/N B = 94 (39 Ge e S/N B = 144 (62.4 Ge S/N B = 420 (200 Ge G 7 2 ( 250 0 7 = 0.2 N B y / S V) S/N B = 30 (14.5 Ge r 200 0.1 a T Me V n i 0.0 m 150 r B,2 i 42 0.1 l e r 100 0.2 P HRG 0.3 spline 0 50 100 150 200 250 300 350 400 single T µ B Me V 0.4 140 160 180 200 220 T/MeV 30/ 30 M. Stephanov Summary CPOD 2017 12 / 1
Lattice susceptibilities vs STAR data Two caveats: M. Stephanov Summary CPOD 2017 13 / 1
Lattice susceptibilities vs STAR data Two caveats: Isospin blind correlations: R B n 2 − 1 ≈ ( R P n 2 − 1) × 2 n − 1 ∆ y ≪ ∆ y corr : R n 2 (∆ y ) − 1 ∼ ∆ y n − 1 M. Stephanov Summary CPOD 2017 13 / 1
Parameterized EOS for hydro simulations M. Stephanov Summary CPOD 2017 14 / 1
Hydrodynamic simulations Baryon stopping and diffusion: Shen Hydrodynamical evolution with sources net baryon density p s NN = 19 . 6 GeV x η valence quark + LEXUS Chun Shen Chun Shen McGill Nuclear seminar CPOD 2017 15/24 24/32 M. Stephanov Summary CPOD 2017 15 / 1
Hydrodynamic simulations Baryon stopping and diffusion: Shen Effects of net baryon diffusion on particle yields C. Shen, G. Denicol, C. Gale, S. Jeon, A. Monnai, B. Schenke, in preparation 0-5% 0-5% AuAu@19.6 GeV � 1 � κ B = C B � µ B � − ρ B T T ρ B 3 coth T e + P • More net baryon numbers are transported to mid-rapidity with a larger diffusion constant Constraints on net baryon diffusion and initial condition Chun Shen CPOD 2017 20/24 M. Stephanov Summary CPOD 2017 15 / 1
Critical slowing down and hydrodynamics Yin M. Stephanov Summary CPOD 2017 16 / 1
Hydro+ M. Stephanov Summary CPOD 2017 17 / 1
Hydro+ M. Stephanov Summary CPOD 2017 18 / 1
Hydrodynamic fluctuations Initial state fluctuations: Long rapidity correlations v n ’s Thermo/hydro-dynamic fluctuations. Correlations over rapidity ∆ y corr ∼ 1 . Critical fluctuations. Even for ξ = 2 − 3 fm ∆ η = ξ/τ ≪ 1 . M. Stephanov Summary CPOD 2017 19 / 1
Dynamics of fluctuations Thermal fluctuations need time to equilibrate. Some modes could remain out of eqlbm. Dynamics of fluctuations: Mazeliauskas, Teaney, Lau, Song This is especially true near critical point due to critical slowing down. This is the origin of the Hydro+ modes. M. Stephanov Summary CPOD 2017 20 / 1
Experiments M. Stephanov Summary CPOD 2017 21 / 1
STAR Net-Proton Fourth-Order Fluctuation Ø Non-monotonic energy dependence is observed for STAR Preliminary 4 th order net-proton, proton fluctuations in most central Au+Au collisions. 𝜆𝜏 5 = 𝐷 2 𝐷 5 Ø UrQMD results show monotonic decrease with decreasing collision energy. August 7, 2017 Roli Esha (UCLA) 11 M. Stephanov Summary CPOD 2017 22 / 1
Control Measurements for CEP Sig ignatures Preliminary HADES result, Quark Matter 2017 0-10% Peak behavior predicted in (QM 2017) κσ 2 critical region: STAR PRELIMINARY FXT Systematic uncertainties included Need M. Stephanov. J. Physics G.: Nucl. Part. Phys. 38 (2011) 124147 data here! FXT measurements needed to determine shape of k σ 2 observable at lower energies 8/11/2017 Kathryn Meehan -- UC Davis/LBNL -- CPOD 2017 6 M. Stephanov Summary CPOD 2017 23 / 1
Control Measurements for CEP Sig ignatures Preliminary HADES result, Quark Matter 2017 0-10% Peak behavior predicted in (QM 2017) κσ 2 critical region: STAR PRELIMINARY FXT Systematic uncertainties included Need M. Stephanov. J. Physics G.: Nucl. Part. Phys. 38 (2011) 124147 data here! FXT measurements needed to determine shape of k σ 2 observable at lower energies 8/11/2017 Kathryn Meehan -- UC Davis/LBNL -- CPOD 2017 6 To draw physics conclusions from this comparison, one needs to take into account rapidity acceptance ∆ y , different in the experiments. Bzdak, Holzmann M. Stephanov Summary CPOD 2017 23 / 1
Acceptance dependence The acceptance dependence consistent with ∆ y n − 1 (Ling-MS 1512.09125; Bzdak-Koch 1607.07375) As long as ∆ y ≪ ∆ y corr the correlators ˆ κ n count the number of n -plets in acceptance. M. Stephanov Summary CPOD 2017 24 / 1
Recommend
More recommend
