Open Heavy Flavor Results from STAR1 Open Heavy Flavor Results from STAR Guannan XIE (for the STAR Collaboration) University of Illinois at Chicago Guannan Xie 2018 RHIC & AGS
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Open Heavy Flavor Results from STAR
Guannan XIE (for the STAR Collaboration) University of Illinois at Chicago
2018 RHIC & AGS Annual Users' Meeting (BNL) Guannan Xie
Introduction
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL) 2
Heavy quarks: mc/b >> ΛQCD, TQGP(RHIC) • Produced early in heavy-ion collisions through hard scatterings • Experience the whole evolution of the system à good probe of medium properties, e.g. transport parameters
arXiv: 1502.02730
Contents
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL) 3
• In medium energy loss D0 RAA, RCP • Hadronization Λc, Ds • Charm conservation Total charm cross-section • Possible medium modification
of spectral function D*+/-
• Mass dependence of energy loss B→(J/ψ, D0, e)
• Probe the longitudinal profile and electromagnetic field
D0 v1 • Transport coefficients D0 v2
STAR Detector
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL) 4
Time Projection Chamber: Tracking, PID (dE/dx),|η|<1, 2π
Time Of Flight detector: PID (1/β), |η|<0.9, 2π
Heavy Flavor Tracker
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL) 5
Heavy Flavor Tracker
HFT: • Silicon Strip Detector: r ~22 cm • Intermediate Silicon Tracker: r ~14 cm • PIXEL detector: r ~2.8 & 8 cm, MAPS, 20.7x20.7 µm2, 0.4%X0(2016) thick, air-cooled
DCAXY Resolution
D0 pT Spectra
Guannan Xie 6
(GeV/c)T
p0 2 4 6 8 10
-2dy
) (G
eV/c
)T
dp Tpπ2ev
N/(N
2 d
7−10
5−10
3−10
1−10
10
20142010/112014(qm15)
Au+Au @ 200 GeVSTAR Preliminary
20)×0-10% (5)×10-40% (
2)×40-80% (
2018 RHIC & AGS Annual Users' Meeting (BNL)
]-2
dy) [
(GeV
/c)
Tdp Tpπ2
evN
/(N2 d
6−10
3−10
1
10
2014
2010/11
(a)(a)(a)
Levy Fit
= 200 GeVNNsAu+Au
10)×0-10% (
2)×10-40% (1)×40-80% (
0.5
1
1.5
0-10%(b)
0.5
1
1.5
10-40%(c)
(GeV/c)T
p0 5 10
0.51
1.5
40-80%(d)
Rat
io
STAR Preliminary
• Precise measurements of D0 spectra extended to low pT and non-central collisions with HFT from 2014 data
• Results consistent with the re-analyzed 2010/11 TPC analysis
D0 RAA
0.5
1
1.5 Run14
Run10/11
(a) 0-10%
= 200 GeVNNsAu+Au
0.5
1
1.5(b) 10-40%
(GeV/c)T
p0 2 4 6 8
0.5
1
1.5(c) 40-80%
AAR
STAR Preliminary
7
• RAA < 1 in the 0-10% centrality interval for all pT • Suppression at high pT increases towards more central collisions • Similar to D-mesons at LHC and high-pT pions at RHIC
(GeV/c)T
p0 2 4 6 8 10
0.5
1
1.5
0-10% STAR0 D
D 0-10% ALICE
LBT
Duke
= 200 GeVNNsAu+Au
(a)
(GeV/c)T
p0 2 4 6 8 10
0.5
1 0-12% STAR±π
0-5% ALICE±h
0-12% STAR±π
0-5% ALICE±h
(b)
AAR
STAR Preliminary STAR:Phys. Lett. B 655 (2007) 104 ALIC
E: JHEP 03 (2016) 081
LBT: Phys. Rev. C94, 014909 (2016)+
private comm.
DU
KE: PRC
92 (2015) 024907+private com
m.
D0 RCP and D0/D0 Ratio
(GeV/c)T
p0 2 4 6 8
0.5
1
1.5
0-10%
Au+Au @ 200 GeV STAR Preliminary
, |y| < 1.00 / D0
D
0.021±1.104 Fit :
(a)
(GeV/c)T
p0 2 4 6 8
0.5
1
1.5
10-20% 20-40% , 0.019±1.071 Fit : 0.015±1.060
(b)
(GeV/c)T
p0 2 4 6 8
0.5
1
1.5
40-60% 60-80% , 0.022±Fit : 1.073 0.039± 0.943
(c)
)0/D0 D
Rat
io (
8
(GeV/c)T
p0 2 4 6 8
0.5
1
1.5 , 0-12%π
, 0-5%0sK
, φ 0 D
LBT Duke
(a) 0-10%
Au+Au @ 200 GeV STAR Preliminary
(GeV/c)T
p0 2 4 6 8
0.5
1
(b) 10-20%
(GeV/c)T
p0 2 4 6 8
0.5
1
(c) 20-40%
(X/4
0-60
%)
cpR
• Significant suppression at high pT . • Reasonable agreement with theoretical calculations • D0/D0 ratio is larger than 1.
一
一
D0 Cross-section and Blast Wave Fit
50
100 2014
2010/11
> 0 GeV/cT
p
Au+Au @ 200 GeV STAR Preliminary
p+p
(a)
partN0 100 200 300
0
0.2
0.4
0.6
0.8 > 4 GeV/c
Tp
(b)
Uncer.partN
b)µ (
y=0
/dy|
NN
σd
> (c)β<0 0.1 0.2 0.3 0.4 0.5 0.6
T (G
eV)
0
0.1
0.2
0.3
0.4Au+Au @ 200 GeV
STAR Preliminary
0D-Ξ,φ
,K,pπ
60-80%
0-10%
60-80% 0-5%
70-80%0-5%
9
• Total D0 cross-section is nearly independent of centrality, and smaller than in p+p. However, for pT > 4 GeV/c it decreases with centrality.
• Blast Wave fits (pT < 5 GeV/c) : suggests earlier freeze-out of D0
Λc and Heavy Quark Hadronization
Guannan Xie 10
• Strong enhancement of Λc/D0 ratio seen in Au+Au collisions.
• Enhancement predicted from coalescence hadronization.
• Enhancements relative to PYTHIA also seen in p+p and p+Pb collisions at LHC.
(GeV/c)T
Transverse Momentum p
0 1 2 3 4 5 6
Bary
on-to
-Mes
on R
atio
s
1−10
1
)0D+0(D
)cΛ+cΛ(
10-60%
PYTHIA
/D)cΛGreco (
Ko: three-quark
0-5%
Ko: di-quark
SHM
STAR Preliminary
Au+Au @ 200 GeV
0 /
Dc
Λ
(GeV/c)T
Transverse Momentum p
QM17
Ko: PRC 79 (2009) 044905. Greco: PRD 90 (2014) 054018 SHM: PRC 79 (2009) 044905. ALICE: arXiv:1712.09581
Λc/D0 in A+A pT and centrality dependence?
Λc Reconstruction
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• More than 50% improvement in signal significance with TMVA BDT • Also new data from 2016 à Effectively 4x more data
2014 (Rectangular) QM17 2014+2016 (BDT)
2018 RHIC & AGS Annual Users' Meeting (BNL)
Λc/D0 : pT Dependence
Guannan Xie 12
• Significant enhancement of Λc/D0 compared to PYTHIA/fragmentation baseline
• The Λc/D0 ratio is comparable with light flavor baryon-to-meson ratios • Consistent with charm quark hadronization via coalescence
-- higher than model predictions, particularly at higher pT
(GeV/c)T
Transverse Momentum p
0 1 2 3 4 5 6
Bary
on-to
-Mes
on R
atio
s
1−10
1
)-π++π()p(p+
60-80%
0-12%
(GeV/c)T
Transverse Momentum p
0 1 2 3 4 5 6
2An
isotro
py P
aram
eter
v
1−10
1
S02K)Λ+Λ(
60-80%
0-5%
(GeV/c)T
Transverse Momentum p
0 1 2 3 4 5 6
2An
isotro
py P
aram
eter
v
1−10
1
)0D+0(D
)cΛ+cΛ(
Ko: three-quark (0-5%)
Ko: di-quark (0-5%)
Greco (0-20%)
PYTHIA
SHM
STAR Preliminary
Au+Au @ 200GeV
10-80%
Bary
on/M
eson
Rat
ios
Transverse Momentum (GeV/c)
Ko: PRC
79 (2009) 044905 Greco: Eur.Phys.J.C
(2018) 78:348 SH
M: PRC
79 (2009) 044905 ALICE: arXiv:1712.09581
Λc/D0 : Centrality Dependence
Guannan Xie 13
• Λc/D0 ratio increases from peripheral to central collisions, indicative of hot medium effects
• Ratio for peripheral Au+Au comparable with p+p value at 7 TeV
ALICE: arXiv:1712.09581
Ds/D0 Enhancement
14
• Strong Ds/D0 enhancement observed in central A+A collisions w.r.t fragmentation baseline
- Strangeness enhancement and coalescence hadronization • Enhancement is larger than model predictions, particularly at higher pT
SHM
ep/pp/ep avg: M Lisovyi, et. al. EPJ C
76, 397 (2016) TAM
U: H
. Min et al. PRL 110, 112301 (2013)
SHM
: A. Andronic et al., PLB 571 (2003) 36
Guannan Xie
Total Charm Cross-section
15
• Total charm cross-section is estimated from the various charm hadron measurements
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
• Total charm cross-section is consistent with p+p value within uncertainties, but redistributed
D0 yields are measured down to zero pT For D+/- and Ds, levy fits to measured spectra are used for extrapolation. For Λc, three model fits to data are used and differences are included in systematics
-- -- --
D*+/D0 Ratio in Au+Au Collisions
16
(GeV)T
p2 4 6 8 10
0/D
*+D
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6Au+Au @ 200GeV
0~10%ALICE, 0~10% Pb+Pb @ 5.02TeVPYTHIA8 (STAR-HF Tune)
STAR Preliminary
>part<N50 100 150 200 250 300 350
Rat
io
00.10.20.30.40.50.60.70.80.9
1 > 0 GeV/c)
T (p- K*/K
Au+Au @ 62.4 GeVCu+Cu @ 62.4 GeVAu+Au @ 200 GeVCu+Cu @ 200 GeV
< 10 GeV/c)T
(2 < p0/D+ D*Au+Au @ 200 GeVPYTHIA8 (STAR-HF Tune)
STAR Preliminary
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
K*/K, Phys. Rev. C (2011)84.3: 034909. ALICE, Collaboration. arXiv:1804.09083.
• Possible hot medium effects : - D*+ life time could become shorter in hot medium - Re-scattering can lead to a yield loss • D*+/D0 ratio in Au+Au collisions at 200 GeV is consistent with
PYTHIA and with ALICE data at higher pT. • Ratio of the integrated yields shows no strong centrality dependence
Non-prompt D0
17
• Strong interaction of charm with the medium. How about bottom? • RAA of non-prompt D0 extracted from the measured non-prompt fraction • Improved signal significance for non-prompt D0 fraction using BDT.
New result down to low pT with 2014+2016 data on the way
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
B Study from Non-prompt J/ψ & D0 & e
18
• Strong suppression for B→ J/ψ and D0 at high pT. • Indication of less suppression for B→e than D→e (~2 𝜎): consistent
with ΔEc > ΔEb • Measurements with improved precision are on the way
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
Note: RAA references (data vs. theory) are different for these comparisons. The decay kinematics needs to be unfolded for different channels.
D0 Directed Flow (v1)
19 Rapidity (y)0.5− 0 0.5
) 1D
irect
ed fl
ow (v
0.1−
0
0.1c)u (0D
)c (u0Ds)u + s (u- + K+K
=200 GeV, 10-80%NNsAu+Au > 1.5 GeV/c
Tp
STAR Preliminary
points shifted along x-axis by 0.040D
-slope from linear fit1v 0.021(syst.)± 0.030 (stat.) ±/dy = -0.102 1 dv0D 0.023 (syst.)± 0.030 (stat.) ±/dy = -0.061 1 dv0D
0.0002(syst.)± 0.0001(stat.) ±/dy = -0.0030 1Kaons dv
2014+2016
一
一
Guannan Xie
一 • Charm and anti-charm quarks can be deflected differently by the initial
EM field → difference between D0 and D0 v1 sensitive to EM field • Charm quarks interact with bulk medium → D0 v1 sensitive to the
initial tilt of the source (bulk) • First observation of non-zero (negative) D0(D0) v1 slope • D0(D0) v1-slope much larger than that of kaons
D0 Elliptic Flow (v2)
20 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
• Published D0 v2 from data taken during 2014 • Clear mass ordering for pT < 2 GeV/c • Follows NCQ-scaling in mid-central (10 - 40%) collisions
Phys Rev. Lett. 118, 212301 (2017)
D0 Elliptic Flow (v2)
21 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
• D0 v2 measurement extended to 0-10% centrality with combined data from 2014 and 2016 runs
• NCQ-scaling test with improved precision • Charm quarks gain significant flow! 2014+2016
Summary
22 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
• Strong modification of charm hadron spectra and hadrochemistry in A+A collisions. (D0 RAA & Rcp, Ds/D0, Λc/D0, D0 v2, D0 v1).
-- total charm quark cross-section conserved -- substantial energy loss & coalescence hadronization -- gain significant flow & may have achieved thermal equilibrium in the medium (D0 v2) -- first observation of non-zero directed flow (v1) for D0.
• Strong energy loss at high pT for B→ J/ψ, and B→D0 measurements. Indication of less energy loss for bottom (B→e), and measurement with better precision on the way.
Summary II – Charm / Bottom
23 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
(GeV/c)T
p0 2 4 6 8
AAR
0.5
1 0-10% 0 D
0-12% STAR±π
= 200 GeVNNsAu+Au
0-10% 0 D
0-12% STAR±π
STAR Preliminary STAR Preliminary
RAA (D0) ~ RAA (π) - lose significant energy v2 (D0) ~ v2 (h) vs. mT - gain significant flow
Experimental : precision measurement of bottom Theoretical : converge on value of transport parameters
Next
Back up
24 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
D0 in AuAu (2010/2011 TPC Analysis) - I Erratum: PRL 113 (2014) 142301
25 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
1. Two mistakes were discovered in calculating TOF related efficiency corrections - Hybrid PID: algorithm inconsistently implemented in data analysis vs. efficiency calculation
- a DCAxy cut efficiency was included in the correction two times 2. p+p measurement: no issue discovered, but the p+p D0 baseline used for RAA is updated
with latest knowledge of charm frag. ratios - considering the pT dependence of D*/D0 frag. ratio - latest world average of c->D0 and c->D* frag. ratios
(D0 at pT<2 GeV/c + D* at 2-6 GeV/c, PRD 86 (2012) 072012)
26 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
(GeV/c)T
p0 1 2 3 4 5 6 7 8
AAR
00.20.40.60.8
11.21.41.61.8
2STAR preliminary
= 200 GeVNNsAu+Au
Centrality 0-10%
2016±D
20140D 2016 Glob. Sys.±D
Glob. p+p uncert.
p+p uncert.
D+/- RAA
• Similar suppression for D0 and D+/-
• Spectra measurement was important for the total charm cross-section
D*+ Production in Au+Au Collisions
27
• D*+ feeds down to D0 yields • Hot medium effects : - D*+ life time could become shorter in hot medium - Re-scattering can lead to loss of yield
D*+ →D0 +π soft+
Phys. Rev. C (2018)97, 034918. Phys. Rev. C (2011)84, 034909
Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
B Study from Non-prompt J/ψ & D0 & e
28 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
Note: RAA references (data vs. theory) are different for different channels
29 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
Directed flow (v1) due to EM fields
• The moving spectators can produce enormously large electromagnetic field (eB ~ 1018 G at RHIC)
• Due to early production of heavy quarks (τCQ ~ 0.1 fm/c) positive and negative charm quarks (CQs) can get deflected by the initial EM force
• D0 and D0 v1 can offer insight into the early time EM fields
30 Guannan Xie 2018 RHIC & AGS Annual Users' Meeting (BNL)
Directed flow (v1) due to hydro
Chatterjee, Bozek: Phys Rev Lett 120, 192301 (2018)
à (v1-slope)CQ >> (v1-slope)LQ CQs much more sensitive to the initial tilt than the charged hadrons
• Heavy quarks are produced according to Ncoll density: symmetric in rapidity
• At non-zero rapidity, CQs production points are shifted from the bulk
• This can induce larger v1 in CQs than light flavors
• Magnitude of CQ v1 depends on the drag parameter used in this model
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