Jets and open heavy flavors in heavy-ion collisions Guang-You Qin

秦广友 Central China Normal University (CCNU)

A symposium on future RHIC and LHC Physics on the occasion of celebrating Miklos Gyulassy's second retirement

September 25-26, 2015, Wuhan, China

Extraction of jet transport coefficients

interaction strength

RHIC energy scan

JET Collaboration, PRC 2014, arXiv:1312.5003

LHC higher energy

McGill-AMY: GYQ, Ruppert, Gale, Jeon, Moore, Mustafa, PRL 2008 HT-BW: Chen, Hirano, Wang, Wang, Zhang, PRC 2011 HT-M: Majumder, Chun, PRL 2012 GLV-CUJET: Xu, Buzzatti, Gyulassy, arXiv: 1402.2956 MARTINI-AMY: Schenke, Gale, Jeon, PRC 2009 NLO SYM: Zhang, Hou, Ren, JHEP 2013

Radiative and collisional energy loss McGill-AMY rad & coll.

GYQ, Ruppert, Gale, Jeon, Moore, Mustafa, PRL 2008

Wicks, Horowitz, Djordjevic, Gyulassy, Nucl.Phys. A784 (2007) 426-442

Both collisional and radiative contributions are controlled by jet transport coefficients

Elastic collisions & parton transport coefficients

•

In the multiple soft scattering limit and keeping up to the second order in a momentum (gradient) expansion, one gets longitudinal drag, longitudinal diffusion & transverse diffusion

   f  1 2 1 2    D L1  D L2 2   DT 2lq  f (L ,lq ,lq  )  2 2 L  l  l   q q  d lq2 4sC R q     DT 2   dy F ( 0 ) F ( y )     2 dL Nc  1 2 2 GYQ, Majumder, PRC 2013; GYQ, Majumder, PRC 2015

Medium-induced radiation •

•

Single gluon emission – –

Multiple-soft-scattering approximation (BDMPS-Z, ASW, AMY) Few-hard-scattering approximation (DGLV, HT)

–

 dN g 2 s q 2 t  P(x ) 4 sin  2  dxdk dt k  2 f

HT:

Multiple gluon emission –

Poisson convolution (BDMPS/ASW/DGLV)

P(E ) 



 n 0

–

 Ng

 n dI( )    E    d n!  i 1 d  

n



1



i   i

BDMPS-Z: Baier-Dokshitzer-MuellerPeigne-Schiff-Zakharov ASW: Amesto-Salgado-Wiedemann AMY: Arnold-Moore-Yaffe DGLV: Djordjevic-Gyulassy-Levai-Vitev HT: Wang-Guo-Majumder

Transport equations (AMY, etc)

df( p ,t )  dt –

e

  

 dkf( p  k ,t )

d( p  k ,k ) d( p ,k )   dkf ( p ,t ) dkdt dkdt

mDGLAP evolution equation (HT)

D~(z ,Q 2 ) s  2  ln Q 2

dy    2 ~( z ,Q 2 ) P ( y ) d  K (  , q , y , Q ) D y  y

Effect of longitudinal scattering on medium-induced gluon radiation •

Medium-induced radiative gluon spectrum with both transverse and longitudinal momentum exchange:

Guo, Wang, PRL 2000; NPA 2001

•

In the small y approximation, the leading contribution from drag and diffusion to medium-induced gluon radiation is:

Y    dN g  s P(y ) D L1 D L2 2DT 2        C dY    2  2 cos A   yq  (yq  )2     2 l2 dydl2 l2    f  med

Unlike (transverse) momentum broadening which induced additional gluon radiation, the longitudinal drag tends to reduce the medium-induced radiation Le Zhang, D. Hou, GYQ, in prep.

Full jets in heavy-ion collisions Fully-reconstructed jets are expected to provide more detailed information than single hadron observables

AJ 

E J ,1  E J ,2 ,   1  2 E J ,1  E J ,2

Strong modification of momentum imbalance & largely-unchanged angular distribution => significant energy loss experienced by the away-side subleading jets

Full jet shower evolution in medium ELrad ,out ELrad ,in

E Lcoll

R

E gcoll

E gbroad

Not only the interaction of the leading hard parton with the medium constituents, but also the fate of radiated shower partons as well dfg(,k 2 ,t ) fg dN gmed 1 2  eˆ  qˆ k fg  dt  4 ddk 2dt 

Ejet = Ein + Elost = Ein + Eout(radiation) + Eout(broadening) + Eth(collision) GYQ, Muller, PRL, 2011; Casalderrey-Solana, Milhano, Wiedemann, JPG 2011; Young, Schenke, Jeon, Gale, PRC, 2011; Dai, Vitev, Zhang, PRL 2013; Wang, Zhu, PRL 2013; Blaizot, Iancu, Mehtar-Tani, PRL 2013; etc.

Energy asymmetry of dijets and -jets di-jets

Young, Schenke, Jeon, Gale, PRC, 2011

He, Vitev, Zhang, PRC 2011

GYQ, Muller, PRL, 2011

-jets

Dai, Vitev, Zhang, PRL 2013

Wang, Zhu, PRL 2013

GYQ, EPJC 2014

Simulating full jet evolution in medium

Solve 3D (energy & transverse momentum) evolution for shower partons inside the jet Include both collisional (via drag and diffusion) and all radiative/splitting processes

Jet energy loss (different contributions)

Ningbo Chang, GYQ, in preparation

Jet shape modification (different contributions)

Ningbo Chang, GYQ, in preparation

Dijet & -jet asymmetry, jet RAA, jet shape

Elastic & radiative energy loss for heavy quarks • •

At low pT, heavy quark energy loss is more dominated by collisional component Langevin approach has been widely utilized at RHIC for heavy quark evolution (Moore, Teaney, PRC 2005; He, Fries, Rapp, PRC 2012; Young, Schenke, Jeon, Gale, PRC 2012 …)

•

Einstein relation (detailed balance):

•

At high pT, , heavy quark energy loss is more dominated by radiative component (similar to light flavors), necessary to include it at the LHC

•

We utilize higher twist (HT) E-loss formalism (Guo, Wang, PRL 2000; Majumder, PRC 2012)

•

HT model for heavy quark radiative energy loss (Zhang, Wang, Wang, PRL 2004)

•

Include gluon radiation contribution as a recoil force exerted on the heavy quark

    dp   D p    fg dt

Short summary of our heavy flavor model • Soft sector (bulk matter): – Initial conditions: Glauber/KLN-CGC for energy/entropy density distribution – Space-time evolution: (2+1)-d viscous hydrodynamics (OSU) – Hadronization: cooper-Frye formula => hadron gas

• Hard Sector (heavy quark): – Initial conditions: Glauber for space distribution and pQCD for momentum distribution (shadowing included) – Heavy quark evolution in QGP: Langevin approach with collisional and radiative energy loss – Hadronization: fragmentation plus coalescence/recombination => heavy mesons

• Heavy mesons evolution in hadron gas: UrQMD model Cao, GYQ, Bass, PRC 2013; PRC 2015

Heavy quark energy loss in QGP (LHC)

• • •

•

QGP medium: (2+1)-D viscous hydrodynamics (OSU) Diffusion coefficient D=6/(2πT), i.e., qhat ~ 2 GeV2/fm at T~350 MeV Collisional energy loss dominates at low energy, while radiative energy loss dominates at high energy The crossing point is larger for bottom than charm quarks due to the mass effect Cao, GYQ, Bass, PRC 2013; JPG 2013; PRC 2015

Heavy meson RAA after QGP (LHC)

• • •

Collisional energy loss dominates at low pT; radiative energy loss dominates at high pT Nuclear shadowing effect leads to a decrease in D meson RAA at low pT, and a mild increase at high pT Fragmentation is sufficient to describe D meson RAA above 8 GeV, but at intermediate pT, recombination becomes important Cao, GYQ, Bass, PRC 2013; PRC 2015

RAA and v2 of D mesons at RHIC

•

Recombination enhances RAA at intermediate pT & produces the bump structure

•

Nuclear shadowing effect leads to a decrease in D meson RAA at low pT, and a mild increase at high pT

•

Recombination increases v2 Cao, GYQ, Bass, PRC 2013; PRC 2015

Heavy meson v2 after QGP (LHC)

• • •

Larger v2 from recombination Different geometries and flow behaviors of the QGP do not significantly influence the overall suppression (not shown), but they may have large impact on heavy flavor v2 KLN-CGC provides larger eccentricity for QGP than Glauber, producing larger D meson v2 Cao, GYQ, Bass, PRC 2013; PRC 2015

Effect of hadronic interaction

Cao, GYQ, Bass, PRC 2015

Mass dependence of RAA (LHC)

Cao, GYQ, Bass, PRC 2015

• • •

A good description of Npart dependence of D meson RAA Using the same diffusion coefficient for c and b quarks, we obtain a reasonable description of non-prompt J/ψ RAA We observe the mass ordering of heavy quark energy loss: ΔEc> ΔEb

DDbar momentum & angular correlations

energy loss

xT=0.2-0.4

xT=0.4-0.6

momentum broadening

xT=0.6-0.8

xT=0.8-1.0

The trigger D/Dbar is along the +y direction Cao, GYQ, Bass, arXiv: 1505.01869

Summary • Radiative and collisional processes – play different roles in different probes (light flavor partons, full jet energy loss and shape function, heavy quarks)

• Jet transport coefficients – control both collisional and radiative contributions – carry much detailed information about the quarkgluon medium (at various scales) – Precise determination of jet transport coefficients (and the full distribution of momentum exchange)

Congratulations to Miklos!