Heavy flavor systematics from PHENIX
Craig Ogilvie, Iowa State University
On behalf of the PHENIX Collaboration
• Complexity of interpreting data from HI collisions
• Use systematics: spectra, elliptic flow,…
• Present d+Au, Cu+Cu, excitation function,…
• Which leads to the complexity of interpreting d+Au…
1
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Sep 27, 2013
Complexity of d(p)+A collisions
 Nuclear structure functions
 Shadowing, saturation at low-x
 Anti-shadowing at moderate, high-x
 Initial state scattering
 Often modeled as increase in effective kT
 Likely largest impact at RHIC where spectra are softer
 Possible collective effects
 Barbara Jacak’s talk on Wed
 Final state energy-loss, absorption,….
 Centrality classification
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Sep 27, 2013
CNM I: d+Au heavy-flavor at 200 GeV
 Non-photonic e, from heavy-flavor decays
Phys. Rev. Lett. 109, 242301 (2012) ,
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Significant enhancement
at moderate pT
Sep 27, 2013
CNM II: d+Au heavy-flavor at 200 GeV
 Non-photonic e, from heavy-flavor decays
Enhancement present in min-bias
Effect not caused by challenges of centrality definition
Phys. Rev. Lett. 109,
242301 (2012)
RdA
PT (GeV/c)
4
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Sep 27, 2013
CNM IV: Forward, backward m from HF decay
m
e
m
Forward rapidity suppressed
Likely shadowing at low-x in Au
Backward rapidity enhanced
anti-shadowing at higher x in Au?
or increase in <kT> due to initial scattering?
5
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Sep 27, 2013
CNM III: Identified hadron spectra in dA
Phys. Rev. C 88,
024906 (2013)
Cronin peak: proton ~ > HFe
Why?
6
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Sep 27, 2013
CNM II: d+Au heavy-flavor at 200 GeV
RdA
Phys. Rev. Lett. 109,
242301 (2012)
PT (GeV/c)
Does <kT> increase have larger impact when p+p spectrum is soft?
spectra = convolution of scattering + fragmentation
Or recombination effects in hadronization?
Or collective? Or…
Opportunity for theory impact
7
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Sep 27, 2013
Example with p0 RdA
 p0 calc from I. Vitev
 Reasonable reproduction of p0
 Nuclear structure function
 Cronin
 Large initial state multiple-
scattering
 Final state Eloss
 Need calculations for heavy-
flavor RdA
Vitev et al., PRD 74 (2006)
Phys.Lett. B718 (2012) 482-487
8
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Sep 27, 2013
J/y CNM
EPS09 nuclear structure functions
plus breakup
Reasonable reproduction, misses
centrality dependence
BUT, charm is enhanced at
moderate pT
(non-photonic electrons RdA>1)
1) Do these calculations reproduce
open charm RdA >1 ?
2) If not, then more effective
suppression needed for J/y
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PRL 107, 142301 (2011)
y
Sep 27, 2013
J/y
Au-going, high-x
d-going, low-x
Normalize J/y by HF?
J/y at mid-y suppressed @low-pt
Charm is enhanced at moderate pt
(non-photonic electrons RdA>1)
Alternative: use dA HF spectra as
baseline?
Phys. Rev. C 87, 034904 (2013)
𝐽/𝜓
𝐻𝐹 𝑒𝑙𝑒𝑐𝑡𝑟𝑜𝑛
•
• Question, what axis? pT ?
RdA
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PT (GeV/c)
Sep 27, 2013
Connect d+Au to A+A
Phys. Rev. Lett. 109,
242301 (2012) ,
Min-bias collisions
1) Enhancement in d+Au + energy-loss  suppression in A+A
2) Models must attempt to reproduce both d+A and A+A
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Sep 27, 2013
One method to organize results
Phys. Rev. Lett. 109, 242301 (2012) ,
Matt Durham
Common suppression pattern when normalized by square of RdA
Does this take into account impact of initial state increase of <kT>?
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Sep 27, 2013
Intermediate Cu+Cu: links d+A and Au+Au
Peripheral Cu+Cu (yellow)
Enhancement ~ central d+Au (blue)
13
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Sep 27, 2013
d+Au to Cu+Cu to Au+Au
Interplay of two effects
CNM increases yield, competes with energy-loss suppression
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Sep 27, 2013
d+Au to Cu+Cu to Au+Au
Higher pT
CNM increases yield, stronger energy-loss suppression
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Sep 27, 2013
Cu+Cu heavy-flavor, forward rapidity
dAu
Cu+Cu forward y, Au+Au mid-rapidity
Large uncertainties: Forward y in central d+Au ~ peripheral Cu+Cu
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Sep 27, 2013
Additional lever arm: beam energy
p0 Phys. Rev. Lett. 109, 152301 (2012)
charged hadrons from Au+Au
pT (GeV/c)
Dominant energy-loss at high s
Transitions to stronger Cronin effect at lower s
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Sep 27, 2013
Need RdA at lower-beam energy
 Not in current RHIC running plan :(
 How does RdA change from 200 GeV to 62 GeV
 Three beam energies (62, 200 GeV, LHC) constrains interplay
of structure function, initial state scattering
 RdA calculations at 62 GeV
 p RdA ~ 2 at 62 GeV
 p RdA ~ 1.2 at 200 GeV
A. Accardi Eur. Phys. J. C 43,
121–125 (2005)
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Sep 27, 2013
Non-photonic electrons Au+Au 62 GeV
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Lower beam energy changes interplay of two effects
Stronger CNM competing with weaker energy-loss
Forthcoming PHENIX publication
spectra with smaller systematics
comparison with p+p, RAA etc.
If your model reproduces 200 GeV and 2.76 TeV heavy flavor RAA
Final call for 62 GeV HF RAA prediction
Sep 27, 2013
HF v2 at lower beam energy
HF flow is > 0 at 62 GeV, but uncertainties large
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Sep 27, 2013
V2 2nd constraint on e-loss Au+Au 200 GeV
 Low-pt Charm v2, extent of thermalization of HF
 Challenge for theory to reproduce both RAA, v2
Many calculations, theory updates past few years
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Sep 27, 2013
One example, P.B. Gossiaux SQM 2013
Elastic + radiative energy loss
With running coupling a
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Sep 27, 2013
Is dpT/pT what we should be plotting for HF?
PRC 87, 034911 (2013)
Suggestion in spirit of workshop,
This is being worked on for HF, but no results available yet
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Sep 27, 2013
VTX Upgrade @ PHENIX
Two layers of silicon pixel detectors
Two layers of silicon strip detectors
Four layers in endcaps
Tracks extrapolate back to collision vertex
Displaced vertices  charm (D), beauty (B)
Requires ~ 50 mm precision
e
X
Installed 2010-12
De+X
Au
Au
B e+X
e
p0 e+e-
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X
e
Sep 27, 2013
VTX p+p results
DCA data are fit by expected DCA shapes of
• Signal components : c  e and b  e (right column)
• Background components (left column)
charm/bottom assumes
PYTHIA spectra
b/(b+c)=0.22+-0.06
Fit range :
0.2<|DCA|<1.5(mm)
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2012/10/23
Sep 27, 2013
VTX p+p results
FONLL consistent with b/(b+c) data
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2012/10/23
Sep 27, 2013
Physics Goal
Energy-loss heavy-flavor  understand nature of sQGP
 Progress on understanding many details
 If a model reproduces a broad range of data
 Can we infer any characteristics of QGP?
 Either direct via a parameter of model
 Diffusion parameter
 Or run same dynamical model in a “box”, e.g. radiation +
collision Eloss
 Infer effective transport parameters
 Which characteristics of sQGP are accessible this way and can we
communicate this to our fellow physicists?
 Maybe too many unsettled aspects yet
27
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Sep 27, 2013
Summary
 Complexity of interpreting d+Au
 Levers: centrality, A, y, s, change impact of
 Structure function, initial state scattering, e-loss,…
 HF RdA enhancement up to factor of 1.5
Call for model calculations
 Is dAu HF a better baseline for RAA HF and dAu J/y
production??
 Complexity of interpreting data from HI collisions
 Cu+Cu HF yields smoothly connects dAu to Au+Au
 Competition between enhancement + suppression
 Change this competition
 Au+Au HF data @ 62 GeV, need dAu running at 62 GeV

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Sep 27, 2013
Backup slides
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Sep 27, 2013
X-ranges
c-cbar
SPS
Pb+Pb
17 GeV
X~10-1
RHIC
Au+Au
200 GeV
X~10-2
LHC
Pb+Pb
5.5 TeV
X~10-3 to 10 -4
Eskola et al. JHEP 0904 (2009) 065
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Sep 27, 2013
RAA of heavy-flavor: from RHIC to LHC
Note to Craig add citations
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Sep 27, 2013
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Sep 27, 2013
Charm production at 62 GeV reproduced
by FONLL
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Sep 27, 2013
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Sep 27, 2013
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Sep 27, 2013
Less bound charmonia in dAu collisions
arXiv:1305.5516
All three systems consistent within uncertainties
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Sep 27, 2013
Less bound charmonia in dAu collisions
arXiv:1305.5516
y’ suppression stronger than J/y for more central dAu collisions
Stronger effective breakup cross-section?
37
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Sep 27, 2013
Photon in dA
Phys.Lett. B718 (2012) 482-487
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Sep 27, 2013