Theory Overview Hard Probes 2018 10012018 Shanshan Cao Wayne State University Outline 1 Overview of heavy quark theoriesmodels at different momentum scales Multiscale approaches for heavy quark energy loss ID: 791757
Download The PPT/PDF document "Open Heavy Flavor Probes of QCD Matter" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
Open Heavy Flavor Probes of QCD Matter(Theory Overview)
Hard Probes 2018 (10/01/2018)
Shanshan CaoWayne State University
Slide2Outline1
Overview of heavy quark theories/models at different momentum scales
Multi-scale approaches for heavy quark energy lossProbing nuclear matter using heavy quarks
Slide3QCD is all about scale!
Low
Q
2
of the exchanged đŸ:
see the whole proton
Increase
Q
2
:
see 3 valence quarks
Further increase
Q
2
: probe PDF
Well known DIS example: what
e
sees in
p
depends on
E
,
Q
2
Heavy quark is a multi-scale object as well â what it sees in QGP also depends on its
E
,
Q
2
2
Slide4Heavy quark physics at different scales
3
Study thermalization process of HQConstrain diffusion coefficient Ds
low
p
T
medium
p
T
Study hadronization process of HQ
Constrain hadron wave-function
high
p
T
Study parton energy loss and mass effect
Constrain jet transport parameter
A multi-scale approach is required for the full picture!
Slide5Overview of heavy quark theories/models4
Low momentum regime
HQ diffusion with đ or Ds as model input
Perturbative calculations of đ LO:
Svetitsky, PRD 37 (1988) Moore, Teaney, PRC 71 (2005)NLO: Caron-Huot, Moore, JHEP 02 (2008)
A factor of over 5 increase at NLO indicates failure of perturbative method
LO
NLO
Lattice QCD calculation of đ
Large error bars
No results for finite momentum HQ yet
No reliable input for model calculations
Slide6Models driven by perturbative and lattice QCD5
Quasi-particle models
Boltzmann transport driven by pQCD scattering matricesâșs(T) and thermal m(T) fitted from lattice EOS -> enhance interactionEg. PHSD [ Song et al., PRC 92 (2015), PRC 93 (2016) ] Catania-QPM [ Scardina et al., PRC 96 (2017) ] AMPT [ Li et al., arXiv:1804.02681 ] ï¶ Liâs talk (Tue.)
Assume two body (
qQ) interaction with V Solve T-matrix and extract Ds
Enhanced energy loss than in pQCD
Recent update: solving V self-consistently in the framework [ Liu et al., PRC 97 (2018) ]
Non-perturbative resonance scattering
(TAMU)
[
Hees
et al., PRC 73 (2006),
PRL 100 (2008)
;
He et al.,
PRC 86 (2012) ]
pQCD
V
=
F
V
=
U
Slide7Gluon radiation from high momentum HQ6
Calculate LO diagrams
[ Kunszt et al., PRD21 (1980) ]Gunion-Bertsch Approximation derived at high energy limit [ Gossiaux et al., JPG 37 (2010); Fochler et al., PRD 88 (2013) ]Eg. Frankfurt (BAMPS) [ Uphoff et al., JPG 42 (2015) ] Nantes (EPOSHQ) ï¶ Gossiauxâs talk (Thur.) Duke (Lido) ï¶
Keâs talk (Tue.)
2->3 scattering with a quasi-particle
Slide8Gluon radiation from high momentum HQ7
Inelastic scattering with a more general mediumHigher-twist: collinear expansion ( )Medium information absorbed in [ Majumder PRD 85 (2012); Zhang, Wang and Wang, PRL 93 (2004) ]
HQ (p)g (l) (k)
Slide9Gluon radiation from high momentum HQ8
Other approachesGLV: soft approximation (z<<1)SCET: soft and collinear approximation BDMPS: multiple scattering induced emission with soft approximationComparison between approaches [ Rapp et al. (EMMI), NPA 979 (2018) ]* Djordjevic
: DGLV; Vitev: SCET; LBL: HT; Nantes: GB+BDMPS; CUJET: DGLV + magnetic monopole HT, SCET and DGLV are consistentDifferent L-dep. with BDMPSAdditional features with magnetic monopoles
Slide109Systematic uncertainty of theory input
[ Cao et al. (JET), arXiv: 1809.07894 ]Fix heavy quark energy loss and explore the systematic error of the extracted transport coefficient.
Slide11Systematic error ONLY due to energy loss
10Convergence of transport parameter into 3 groups when energy loss in a brick is under controlCan be further distinguished by future data on 2-particle correlationelastic: QPMelastic: pQCD or
T-matrixelastic + inelasticCommon baseline: same initial c spectrum, static medium T = 250 MeV, L = 3 fm, RAA(c) = 0.3 at pT = 15 GeV
Slide12Hadronization models11
High momentum heavy quarks fragment into hadrons [fragmentation mechanism: Petersen, FONNL, Pythia, etc.]Low momentum quarks combine with thermal partons into hadrons [recombination (coalescence) mechanism]
Non-perturbative process
No first principle calculation yet
Slide13(
D ΠΣ ΠΩ )Recombination (coalescence) models12
Resonance RecombinationGive smaller and softer D
spectra than instantaneous recombination
time window for resonance states
formation rate
[ He et al. PRC 86 (2012) ]
[ Rapp et al. (EMMI), NPA 979 (2018) ]
Instantaneous recombination
Probability: Wigner function
Easy to extend to 3-body system
[ Duke, LBL, Catania, Nantes, PHSD, etc. ]
Slide14Effects of recombination at medium
pT13
Enhance D0 RAAEnhance D0 v2Enhance
Îc/D0
ratioChallenge (puzzle): Îc
vs. D0 chemistry (currently overestimate D
0 while underestimate Îc yield)
Slide15Multi-scale approaches for HQ energy loss
14
[ Cao et al., arXiv: 1711.09053 ] Scale 2 (Q ~ MHM) Transport model with rate equation
Scale 1: Q>>MHM HQ fragmentation function is treated with DGLAP equation
Input 1: medium-induced splitting function (higher-twist):
Input 2: fragmentation function at low scale
Q0 ~ MHM:
Example 1: DGLAP + transport evolution
A complete description of HQ evolution requires multi-scale approaches.
Slide16Evolution of
b
-quark fragmentation functionin-mediumtransportvac
DGLAP
medium-modifiedDGLAP
15
Slide17Nuclear modification of heavy mesons
16
ï¶ Majumderâs talk (Tue.)
Slide1817
Example 2: Boltzmann + Langevin transport
BM: scattering between quasi-particles
BM + small momentum transfer (k) -> LVLV deviates from BM when
k<<p (or M
/T>>1) is not satisfiedLV can be extended to non-quasi-particle medium where BM does not apply
Neither BM nor LV alone is sufficient for HQ interaction with QGP!
[ EMMI, NPA 979 (2018) ]
Lido
(
Li
nearized Boltzmann with
d
iffusion m
o
del) (Duke)
large
k
(<
k
0
)
HQ sees quasi-particle
Boltzmann
small
k
(<
k
0
)
HQ cannot see quasi-particle
Langevin
ï¶
Keâs
talk (Tue.)
[
Ke
, Xu and Bass,
arXiv
: 1806.08848 ]
Slide1918Probing nuclear matter with heavy quarks
Yes! [ Xu et al., arXiv:1809.10734 ]DFNCC (Duke-Frankfurt-Nantes-Catania-CCNU)Different initial condition of the bulk (PHSD vs. Trento), same hydrodynamic model and heavy quark transport modelSimilar Δ2 and v
2 of the bulkDifferent c v2: probe different bulk historyCan heavy quark probe medium history?
Slide2019v
2 puzzlep-Pb data: inconsistent picture between v2 and RAA Slight suppression
Large D v2 up to 8 GeVWhat mechanism could build up v2 without requiring energy loss?Heavy-light quark recombination? But heavy quarkoniumâs v2 in p-Pb is also large âŠReally QGP effect or actually initial state effect?
Slide2120v
2 puzzleThe v2 puzzle actually exists everywhere! Quarkonium in p-A
D in A-ACharged hadron in A-ADirect photon in A-A
Slide2221Insufficient discussion of jet-
Glasma interactionPre-equilibrium state is long â Ï0 = 1.2 fm for hydro from Bayesian calibration to bulk data. [ Auvinen et al., PRC 97 (2018) ]Correlation between multiple scatterings in Glasma could result in v2 of hard probes without causing energy loss.Future effort:v2 of direction photon in p-Pb
? -> Glasma vs. plasma bulkProbe initial state with heavy quarksShort formation time: interact with I.S.Long relaxation time: I.S. effect remain [ Das et al., PLB 768 (2017); Ruggieri and Das, arXiv:1805.09617 ] ï¶ Mrowczynskiâs talk (Tue.)
Slide23Summary
Overview of heavy quark energy loss and hadronization theories/models at low, medium and high pT scales Multi-scale approaches for heavy quark energy loss DGLAP + transportBoltzmann + LangevinProbing nuclear matter using heavy quarks
Probing bulk evolution historyProbing initial state effects 22
Thank you!
Slide2423
A numerical framework for multi-scale evolution
Initial geometry of
Nucleus-Nucleus collision
Hard Particle Production
Initial Soft
Density
distribution
Hard & Semi-hard Hadoronization
Cooper-Frye
Sampling
Hadronic Cascade
Multi-stage
Jet Shower Evolution
Viscous Fluid dynamics of QGP
JETSCAPE Event Generator
Multi-stage
Jet Shower Evolution
Download:
https://github.com/JETSCAPE
Embed your own energy loss model and specify its applicable region in phase space
ï¶ Talks:
Soltz
(Tue.), Tachibana (Wed.), Park (Thur.)
Slide25Momentum scale dependence of collisional vs. radiative energy loss
24
Collisional energy loss dominates low energy region, while radiative dominates high energy region.Crossing point: 7 GeV for c and 18 GeV for b quark.Collisional energy loss alone may work well to describe low pT data at RHIC but is insufficient for high
pT data at LHC.
Slide26Gluon radiation from high momentum HQ25
Inelastic scattering with a mediumHigher-twist: collinear expansion ( )[ Majumder PRD 85 (2012); Zhang, Wang and Wang, PRL 93 (2004) ]
Recent updates on HQ theory within HT:Ensuring gauge invariance â larger HQ energy loss at low Q2 [ Du et al., PRD 98 (2018) ]Longitudinal drag ( ) and diffusion ( ) induced gluon emission for slow HQ [ Abir et al., PRD 90 (2014), PRC 94 (2016) ] ï¶ Majumderâs talk (Tue.)
Medium information absorbed in
HQ (
p
)
g
(
l
)
(
k
)
Slide27Gluon radiation from high momentum HQ26
Calculate LO diagrams
[ Kunszt et al., PRD21 (1980) ]Gunion-Bertsch Approximation derived at high energy limit [ Gossiaux et al., JPG 37 (2010); Fochler et al., PRD 88 (2013) ]Adding the LMP effect by enforcingEg. Frankfurt (BAMPS) [ Uphoff et al., JPG 42 (2015) ] Nantes (EPOSHQ) ï¶ Gossiauxâs talk (Thur.) Duke (Lido)
ï¶ Keâs talk (Tue.)
2->3 scattering with a quasi-particle
Slide2827Systematic uncertainty of theory input
5
[ Cao et al. (JET), arXiv: 1809.07894 ]A factor of 5 difference in the extracted transport parameter!
Slide2928
p-Pb data:Slight suppressionFinite v2
HQ is good probe of the initial state:Short formation time: interact with I.S.Long relaxation time: I.S. effect remainInteract with GlasmaNon-unit RpPb
[ Das et al., PLB 768 (2017) ]
Interact with E, BSizable v
1Opposite sign for D and
[ Ruggieri and Das, arXiv:1805.09617 ]
ï¶
Mrowczynski
âs
talk (Tue.)