jet-like correlations of heavy-flavor particles - from rhic to lhc
DESCRIPTION
Jet-like correlations of heavy-flavor particles - From RHIC to LHC. Andr é Mischke Utrecht University. 27 th Winter Workshop on Nuclear Dynamics Winter Park, Colorado – February 6-13, 2011. Outline. Introduction Results from RHIC Simulation studies at LHC energies Summary. 2. - PowerPoint PPT PresentationTRANSCRIPT
Jet-like correlations of heavy-flavor particles
- From RHIC to LHC
André MischkeUtrecht University
27th Winter Workshop on Nuclear DynamicsWinter Park, Colorado – February 6-13, 2011
WWND 2011
• Introduction
• Results from RHIC
• Simulation studies at LHC energies
• Summary
Andre Mischke (ERC-UU) 2
Outline
Wicks et al., Nucl. Phys. A784, 426 (2007)
Energy loss of heavy quarks
bottomcharm
Gluon radiation probability:
partonhot and dense medium• Higher penetrating power
(mQ>> Tc, QCD) probe deeper into the medium
• Dead-cone effectgluon radiation suppressed at small angles (q < mQ/EQ)
Y. Dokshitzer, D. Kharzeev, PLB 519, 199 (2001), hep-ph/0106202
• Less energy loss Eg > ELQ > EHQ
€
ω dIdω HEAVY
=ω dI
dω LIGHT
1+mQ
EQ
⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
21
θ 2
⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
2
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mc ≈ 260 mu,d
mb ≈ 3.5 mc
WWND 2011Andre Mischke (ERC-UU)
RAA of single electrons at RHIC
4
light quark hadrons
• RAA(e) ≈ RAA(h) at pT > 6 GeV/c
• Not in line with expectations from dead-cone effect
– A. Adil and I. Vitev, PLB649, 139 (2007)
Phys. Rev. Lett. 98, 192301 (2007) arXiv:1005.1627, subm. to PRCPhys. Rev. Lett. 98, 172301 (2007)
c e+ + X (BR = 9.6%)b e+ + X (BR = 10.86%)
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D and B contributions to single electrons
NLO pQCD: D/B meson crossing point is largely unknown
M. Cacciari et al., PRL 95, 122001 (2005)
Andre Mischke (ERC-UU) 5
– charm- - bottom
charm production
trigger side
probe side
3.83
%
54%
~
10%
K-
b
b
B-
D*0
D0
+
e
e-
B+
-
K+
D0
like-sign pairs near-side correlation
unlike-sign pairs away-side correlation
Identify and separate charm and bottom quark pairs using
• their decay topology
• azimuthal angular correlation of their decay products
Heavy-flavor particle correlations
WWND 2011Andre Mischke (ERC-UU)
–
–
–
Near- and away-side correlation peak expected for B decays
6
A.M., PLB 671, 361 (2009)
PYTHIA, pp@200 GeVlike-sign pairs
bottom dominantcharm dominant
WWND 2011Andre Mischke (ERC-UU)
Single electron - D0 azimuthal correlations
essentially from B decays only
75% from charm25% from beauty
STAR, Phys. Rev. Lett. 105, 202301 (2010)
7
Extraction of relative B contribution using different models:
1measured B DR R
Exploit different fragmentation of associated jets
Electron-hadron azimuthal correlations
WWND 2011Andre Mischke (ERC-UU)
PHENIX, Phys. Rev. Lett. 103, 082002 (2009) STAR, Phys. Rev. Lett. 105, 202301 (2010)
8X. Lin, arXiv:hep-ph/0602067
Phys. Rev. Lett. 103, 082002 (2009) Phys. Rev. Lett. 105, 202301 (2010)
B and D contributions comparable at pT > 5 GeV/c and consistent with pQCD calculation at Fixed-Order plus Next-to-Leading Logarithm (FONLL)
WWND 2011 9Andre Mischke (ERC-UU)
B contribution to single electrons
Phys. Rev. Lett. 105, 202301 (2010)
I: M. Djordjevic et al., PLB 632, 81 (2006)II: R. Sharma et al., PRC80, 054902 (2009)III: H. van Hees et al., PRL 100, 192301 (2008)
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RAA = rB RAAeB + (1-rB) RAA
eD
pT > 5 GeV/c
• B production in heavy ion collisions stronger suppressed at high pT than expected
• Original radiative energy loss calculation excluded
• Direct D and B measurements in heavy-ion collisions will come in the near future (silicon μ-vertex detector upgrades)
Comparison to energy loss models
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Single electron-hadron correlations in A+A
• Away-side modification?• Improved statistics and better background rejection
needed for conclusion
PHENIX, arXiv:1011.1477, subm. to Phys. Rev. C G. Wang, Hard Probes 2010
Heavy flavor production at LHC
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• Maximal collision energy: √sNN = 5.52 TeV
• Expected initial energy density: ~100 GeV/fm3 (10 times higher than at RHIC)
• Relatively long-lived QGP phase• Thermal equilibrium reached
much faster(?)
Most of the in-medium effects should be enhanced• Higher heavy-flavor production rates
€
σ LHCcc ≈ 25 ×σ RHIC
cc
σ LHCbb ≈100 ×σ RHIC
bb
system, sNN
pp @ 14 TeV Pb-Pb (0-5%) @ 5.5 TeV
0.16 / 0.006 115 / 4.6QQtotN
Charm and bottom yields- NLO pQCD predictions using MNR PDF- ~factor 2 uncertainty for Pb-Pb from NLO and shadowing
Single electron RAA and correlations at LHC
T0 = 1 GeVt0 = 0.15 fm/c# quark flavours: 2
Pyquen: Pb-Pb(5%) @ 5.5 TeV
pp: PythiaPb-Pb: Pyquen
• Near side: B decays and charm from gluon splitting
• Away side: charm flavor creation
5 < pTele < 7.5 GeV/c
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Light hadrons
• Electron RAA similar to results from “more sophisticated” energy loss model calculations
Single electron – D0 azimuthal correlations2 < pT
trig-ele < 4 GeV/c
• Near side: B decays and gluon splitting charm• Away side: charm flavor creation 900M events
PythiaPyquen
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Pyquen: Pb-Pb(5%) @ 5.5 TeV
14
different D0 pT bins
(e, D0): Near-side width and IAA
2 < pTtrig-ele
< 4 GeV/c
IAA of near-side yield
• Slightly broader peak for Pyquen compared to Pythia• Suppression of D0 yield for Pyquen• Next: fragmentation function
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c
cbar
g
g
flavor creation gluon splitting
g
g
g
g
c
cbar
0
Charm production: NLO processesE. Norrbin, T. Sjostrand, Eur. Phys. J. C17, 137 (2000)
Leading order- flavor creation (FC)
Next-to-leading order - gluon splitting (GS)- flavor excitation
NLO processes become important at LHC energies
RHIC LHC
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Gluon splitting contribution
GS charm + B decaysGS charm only
NLO processes become important at LHC
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MC@NLOLO PYTHIA
like-sign e-K pairs3 < pT < 7 GeV/c
A. M., Phys. Lett. B671, 361 (2009)
p+p@200 GeV
RHIC LHC
Azimuthal correlations of single electrons and D0: gluon splitting contribution appears at near-side
MC@NLO
LHC ?
Gluon splitting rate
“D* in jet” measurement - different fragmentation characteristic
- soft charm FF for gluon jets
STAR, Phys. Rev. D79, 112006 (2009)
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jet axisD*
hard (FC)soft (GS)
zz = pL(D*)/Egluon-jet
• UA1 jet reconstruction Rcone size = 0.4 Ethr = 10 GeV
• standard D*+ reconstruction
• lower background
“D*+ in jet” analysis
• 1.1M 7 TeV pp jet events
• Charged track jets in |η| <
0.5
• 4 jet algorithms compared
• Uncorrected spectra
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A. Grelli, HQ2010
gluon splitting +flavor creation
Full PYTHIA simulation, pp@10 TeV
• Prove of principle• Needs more
statistics and efficient trigger
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Δ between leading particles and D*+
20
A. Grelli, HQ2010
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• Heavy quarks - particularly good probes to study the properties of hot quark matter
(especially the transport properties)
- abundantly produced at LHC energies
• Jet-like correlations of heavy-flavor particles allow to study modification of fragmentation function in the QCD medium
• NLO processes (such as gluon splitting) become important: accessible via “charm content in jets” measurements
• Many more to come!
Summary
Backup
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Single electron RAA at LHC
T0 = 1 GeVt0 = 0.15 fm/c# quark flavors: 2
Pyquen: Pb-Pb(5%) @ 5.5 TeV
H. van Hees and R. Rapp, 2007
I. Vitev, A. Adil & H. van Hees, 2007Pyquen • Pythia afterburner• Radiative (generalisation of
BDMPS) and collisional energy loss (high-pT approximation)
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(e,D0) correlations for like-sign pairs
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Near-side width and yield
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Near-side IAA
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