Quark chemical equilibrabon for thermal photon ellipbc flow

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AM, Phys. Rev. C 90, 021901(R) (2014) AM, arxiv:1408.

Monnai RIKEN BNL Research Center Nishina Center for Accelerator- Based Science,

1 AM, Phys. Rev. C 90, (R) (2014) AM, arxiv: [nucl- th] Quark chemical equilibrabon for thermal photon ellipbc flow Akihiko Monnai RIKEN BNL Research Center Nishina Center for Accelerator- Based Science, RIKEN Thermal Photons and Dileptons in Heavy- Ion Collisions 21 st August 2014, Brookhaven NaBonal Laboratory, NY, USA

) The QGP created in high- energy heavy ion collisions is quanbfied as a relabvisbc fluid with extremely small viscosity Au- Au, Au-

2 IntroducBon n Quark- gluon plasma (QGP): many- body system of deconfined quarks and gluons Graphics by AM Hadron phase (crossover) sqgp QGP phase (wqgp?) The QGP created in high- energy heavy ion collisions is quanbfied as a relabvisbc fluid with extremely small viscosity Au- Au, Au- Cu (200 GeV) and U- U (193 GeV) at RHIC Pb- Pb (2.76 TeV) at LHC It is a QCD phenomenon; what can an electromagnebc probe tell us? LHC RHIC Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: IntroducBon 2 / 15

3 IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Hadronic fluid QGP fluid Graphics by AM Saturated gluons z The hot medium is opaque in terms of QCD; transparent in terms of electromagnebsm Hadrons: Most of informabon before freeze- out is lost Photons: Retain informabon during Bme evolubon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: MoBvaBon 3 / 15

IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Graphics by AM Saturated gluons Hadronic fluid QGP fluid z Prompt - from hard processes The hot medium is opaque in terms of

4 IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Graphics by AM Saturated gluons Hadronic fluid QGP fluid z Prompt - from hard processes The hot medium is opaque in terms of QCD; transparent in terms of electromagnebsm Hadrons: Most of informabon before freeze- out is lost Photons: Retain informabon during Bme evolubon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: MoBvaBon 3 / 15

5 IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Graphics by AM Saturated gluons Hadronic fluid QGP fluid z Thermal (hadronic) Thermal (QGP) - from black- body radiabon Prompt - from hard processes The hot medium is opaque in terms of QCD; transparent in terms of electromagnebsm Hadrons: Most of informabon before freeze- out is lost Photons: Retain informabon during Bme evolubon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: MoBvaBon 3 / 15

6 IntroducBon n Photon emission in heavy ion collisions (low p T ) Graphics by AM Saturated gluons Hadrons t Hadronic fluid QGP fluid z Decay - from hadronic decay Thermal (hadronic) Thermal (QGP) - from black- body radiabon Prompt - from hard processes The hot medium is opaque in terms of QCD; transparent in terms of electromagnebsm Hadrons: Most of informabon before freeze- out is lost Photons: Retain informabon during Bme evolubon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: MoBvaBon 3 / 15

7 IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Decay - from hadronic decay Graphics by AM Saturated gluons Hadronic fluid QGP fluid z Thermal (hadronic) Thermal (QGP) - from black- body radiabon Prompt - from hard processes Direct The hot medium is opaque in terms of QCD; transparent in terms of electromagnebsm Hadrons: Most of informabon before freeze- out is lost Photons: Retain informabon during Bme evolubon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: MoBvaBon 3 / 15

IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Decay - from hadronic decay Graphics by AM Saturated gluons Hadronic fluid QGP fluid z Thermal (hadronic) Thermal (QGP) -

8 IntroducBon n Photon emission in heavy ion collisions (low p T ) Hadrons t Decay - from hadronic decay Graphics by AM Saturated gluons Hadronic fluid QGP fluid z Thermal (hadronic) Thermal (QGP) - from black- body radiabon Prompt - from hard processes Direct The hot medium is opaque in terms of QCD; transparent in terms of electromagnebsm Hadrons: Most of informabon before freeze- out is lost Photons: Retain informabon during Bme evolubon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: MoBvaBon 3 / 15

9 MoBvaBon n Experiments have posed photon v 2 puzzle Direct photon v 2 is large; no definite answer so far - Hydrodynamic models predict small flow harmonics because of the contribubon from earlier stages with likle ellipbc flow - Viscosity? MagneBc field? Pre- equilibrium flow? Modified photon emission rate? Direct photon v 3 is also LARGE PHENIX, PRL 109, No centrality dependence Talk by S. Mizuno (PHENIX) at QM14 The enhancement is at least parbally due to the properbes of the hot medium itself Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Photon v n problem 4 / 15

10 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Thermal Photons and

11 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong

12 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

13 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Other effects which work on are

14 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Other effects which work on are missing Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

15 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Other effects which work on are missing Bulk evolubon needs modificabon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

16 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Other effects which work on are missing Bulk evolubon needs modificabon Experimental data needs more stabsbcs Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

17 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Other effects which work on are missing Bulk evolubon needs modificabon Experimental data needs more stabsbcs This talk Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

18 Photon v n puzzle n Possible (not all) reasons: an overview Bulk Collision Pre- equilibrium EquilibraBon Hydrodynamics Hadron gas Correct Photons QGP thermal Hadronic thermal (Decay ) Prompt Wrong Thermal photon emission/v n esbmate needs modificabon Prompt photon emission/v n esbmate needs modificabon Other sources of are not considered Other effects which work on are missing Bulk evolubon needs modificabon Experimental data needs more stabsbcs This talk + preview Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 5 / 15

Approach of this work n Bulk evolubon Graphics by AM τ > 10 fm/c: Hadronic gas τ ~ 1-10 fm/c: QGP/hadronic fluid EquilibraBon τ ~ 0-1 fm/c: Glasma Likle bang τ < 0 fm/c: Color glass condensate -

19 Approach of this work n Bulk evolubon Graphics by AM τ > 10 fm/c: Hadronic gas τ ~ 1-10 fm/c: QGP/hadronic fluid EquilibraBon τ ~ 0-1 fm/c: Glasma Likle bang τ < 0 fm/c: Color glass condensate - Color glass condensate (CGC): Colliding nuclei are saturated gluons - QGP/hadronic fluid: Equilibrated quark- gluon plasma Chemical equilibrabon does not necessary coincides with thermalizabon (cf: AM and B. Müller, arxiv: ) Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Approach of this work 6 / 15

Approach of this work n Fewer quarks + more gluons at the onset of QGP fluid p y p y p y p x p x p x Equilibrated QGP (small v 2 ) Quark- gluon plasma We consider: Non- equilibrated QGP quark- GLUON

20 Approach of this work n Fewer quarks + more gluons at the onset of QGP fluid p y p y p y p x p x p x Equilibrated QGP (small v 2 ) Quark- gluon plasma We consider: Non- equilibrated QGP quark- GLUON plasma Quark- gluon plasma quark- gluon plasma Flow anisotropy develops (medium v 2 ) Quark- gluon plasma Quark- gluon plasma ContribuBon of later stage becomes large as thermal are emiked in the presence of quarks; photon v 2 can be enhanced Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: The model 7 / 15

The model n (2+1)- dimensional ideal hydrodynamic model + rate equabons The energy- momentum conservabon (a) gluon spliung Quark and gluon number changing processes p zp (1 z)p zp (1 z)p p (b) quark

21 The model n (2+1)- dimensional ideal hydrodynamic model + rate equabons The energy- momentum conservabon (a) gluon spliung Quark and gluon number changing processes p zp (1 z)p zp (1 z)p p (b) quark pair producbon p zp zp p (1 z)p (1 z)p (c) gluon emission from a quark : reacbon rates : parton densibes (in equilibrium) p zp (1 z)p zp (1 z)p p Late quark chemical equilibrabon implies as the chemical equilibrabon Bmes are Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Input for numerical analyses 8 / 15

22 Input for numerical analyses n Hydrodynamic parameters (IniBal condibons + fluid properbes) Gluon energy distribubon: Quark energy distribubon: 0 GeV/fm 3 IniBal Bme: 0.4 fm/c EquaBon of state: Hadron resonance gas (mass below 2 GeV) + Parton gas (N f = 2) Chemical reacbon rates: where ranges are ( ) and ( ) n Photon emission rate Kolb, Sollfrank and Heinz, PRC 62, (2000) where Turbide, Rapp and Gale, PRC 69, and Traxler and Thoma, PRC 53, 1348 Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Results 9 / 15

23 Results n EllipBc flow of thermal c b dependence v v2 (eq) v2 (c =0.2, c b 0.2 v2 (c =0.5, c b v (c =2.0, c Thermal photon v2 2 b =1.5) a,c =1.5) a,c =1.5) a,c ) -3 (fm n q 12 eq n q n q 10 n q n q Quark number density (c =0.2, c b (c =0.5, c b (c =2.0, c b =1.5) a,c =1.5) a,c =1.5) a,c p (GeV) T Late quark chemical equilibrabon ( (fm/c) ) leads to enhancement of thermal photon v 2 is mobvated in an early equilibrabon model (AM and B. Müller, arxiv: ) for Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Results 10 / 15

24 Results n EllipBc flow of thermal c a,c dependence v v2 (eq) v2 (c =0.5, c b 0.2 v2 (c =0.5, c b v (c =0.5, c Thermal photon v2 2 b =0.0) a,c =1.5) a,c =3.0) a,c ) -3 (fm n g 16 eq n g 14 n g n g 12 n g Gluon number density (c =0.5, c b (c =0.5, c b (c =0.5, c b =0.0) a,c =1.5) a,c =3.0) a,c p (GeV) T (fm/c) Thermal photon v 2 is moderately enhanced for faster gluon- involved equilibrabon processes because quark producbon in early stages is suppressed due to quicker dampening of gluon overpopulabon due to recombinabon Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Results 11 / 15

25 Results n Transverse momentum spectra of thermal ) -2 dy (GeV dp /p (1/2 )dn T T Thermal photon parbcle spectra equilibrium c b =0.2, c a,c =1.5 c b =0.5, c a,c =1.5 c b =2.0, c a,c = p (GeV) T p T spectra is reduced by late quark chemical equilibrabon Effect is limited for the chosen input; however more sophisbcated photon emission rate and equabon of state would be important (Cf. Gelis et al., JPG 30, S1031) Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Summary and outlook 12 / 15

26 Summary and outlook n Thermal photon v 2 from chemically non- equilibrated QGP is invesbgated Late quark producbon leads to visible enhancement of v 2, contribubng posibvely to resolubon of photon v 2 puzzle EvoluBon of bulk medium from CGC to QGP is a key Late gluon equilibrabon slightly reduces v 2 Net yield of thermal is reduced n Future prospects include: IntroducBon of dynamical equabon of state, more realisbc inibal condibons, shear and bulk viscosibes etc. EsBmaBon of the contribubon from prompt Other effects in non- equilibrated QGP, e.g., heavy quarks Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: Prompt photon v n 13 / 15

$1410 [nucl- th] Transparent medium has a non- unity refracbve index A hot QCD medium works as a 4D$ lens Geometrical anisotropy (ε 2, ε 3, ) is directly mapped onto thermal and prompt photon flow

lens Geometrical anisotropy (ε 2, ε 3, ) is directly mapped onto thermal and prompt photon flow

w/ the model index based on HTL - CriBcal opalescence near T c?

012 0.01 0.008 0.006 0.004 0.002 0-0.002 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.

27 Prompt photon v n n OpBcal effects in QGP medium AM, arxiv: [nucl- th] Transparent medium has a non- unity refracbve index A hot QCD medium works as a 4D lens Geometrical anisotropy (ε 2, ε 3, ) is directly mapped onto thermal and prompt photon flow harmonics (v 2, v 3, ) Numerical analyses prompt photon v n PosiBve flow harmonics; not large enough w/ the model index based on HTL - CriBcal opalescence near T c? - Semi- transparency at ultra- low momentum (determining plasma frequency of QGP)?,prompt v n (GeV) p T, prompt 2,3,4,5, prompt v v v v v 2, prompt 3, prompt 4, prompt 5 (a=0) (a=1) (a=1) (a=1) (a=1) Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: The end 14 / 15

28 The end n Thank you for your akenbon! n Website: hkp://tkynt2.phys.s.u- tokyo.ac.jp/~monnai/ Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: 15 / 15

Momentum anisotropy n Time evolubon of medium ellipbc flow Song & Heinz, PRC 78, 024902 EllipBc flow is quickly developed Effects of

29 Momentum anisotropy n Time evolubon of medium ellipbc flow Song & Heinz, PRC 78, EllipBc flow is quickly developed Effects of inibal absence of quarks would be large Thermal Photons and Dileptons in Heavy- Ion Collisions, 21 st August 2014, BNL, USA Next slide: / 15

Constraining the QCD equation of state in hadron colliders

Constraining the QCD equation of state in hadron colliders Akihiko Monnai (KEK, Japan) with Jean-Yves Ollitrault (IPhT Saclay, France) AM and J.-Y. Ollitrault, Phys. Rev. C 96, 044902 (2017) New Frontiers