Heavy flavor Heavy flavor production at RHIC production at RHIC Yonsei Univ. Yonsei Univ. Y. Kwon Y. Kwon
Jan 05, 2016
Heavy flavor production at RHICHeavy flavor production at RHIC
Yonsei Univ.Yonsei Univ.
Y. KwonY. Kwon
ContentsContents
• Introduction Introduction • Current measurementsCurrent measurements
– Total cross sections by PHENIX and STARTotal cross sections by PHENIX and STAR– Related differential cross sectionsRelated differential cross sections– RRAAAA, flow, and further results, flow, and further results– Charm/Bottom ratioCharm/Bottom ratio
• How do we obtain the result?How do we obtain the result?– Direct reconstructionDirect reconstruction– Non-photonic e & prompt Non-photonic e & prompt
• Results at higher energyResults at higher energy• A question?A question?
3
Introduction : heavy quarks as a probe
p+p :
pQCD test
baseline for A+A
A+A :
flow thermalization
high pT suppression
energy loss
parton
medium
light
ENERGY LOSS
%07.080.3..
,, 00
RB
KDKD
Direct: reconstruction of all decay products
Indirect: charm and beauty via electronsc e+ + anything (B.R.: 9.6%)b e+ + anything (B.R.: 10.9%)issue of photonic background
charm (and beauty) via muonsc + + anything (B.R.: 9.5%)
Introduction : Introduction : (open) heavy flavor measurement (open) heavy flavor measurement
Total cross sections,PHENIX vs STARTotal cross sections,PHENIX vs STAR
Binary scalingSTAR results ~ 2 times larger than PHENIX
Forward prompt Forward prompt -- production production (PHENIX) (PHENIX)
PPG057 : PRD76, 092992(2007)
Leptons from HLeptons from Heavy flavor,eavy flavor, PHENIX PHENIX
PHENIX Preliminary
PRL, 98, 172301 (2007)
Systematically higher than FONLL calculation
e yield shows binary scaling, high pT suppression in central Au+Au
p+p 200GeV/c
8
Leptons from Leptons from heavy flavor, heavy flavor, STARSTAR
STAR Preliminary
• Combined fit of , D0, low pT e
• Low pT muon constrains charm cross-section
c dominant
b dominant
Heavy quarks in p+p from eHeavy quarks in p+p from e++ee-- at PHENIX at PHENIX
d+Au: no suppression expected slight enhancement
expected (Cronin effect) Peripheral Au+Au:
no suppression expected Semi-Central Au+Au: very little suppression expected
STAR hadrons pT> 6 GeV/c
Central Au+Au: less suppression expected ?
RRAAAA
t
pp
t
AA
colltAA
dp
dNdp
dN
NpR
1)(
Nuclear modification factor
Energy Loss?Energy Loss?
Elliptic flow vElliptic flow v22 – NPE from HF decays – NPE from HF decays
PHENIX RUN4 : PRL, 98, 172301 (2007)
How do we obtain the result?How do we obtain the result?
STAR Preliminary
Direct D-meson reconstruction Direct D-meson reconstruction ((STARSTAR))
D0
Phys. Rev. Lett. 94 (2005)
No displaced vertex used
7.4~/ NS
Non-photonic electrons
Inclusive electrons = photonic + non-photonic electron
Direct measurement :converter method
Estimation based on other(PHENIX) measurement :
Cocktail method
Dominant background : 0 Dalitz decay, conversion
Mostly from heavy quark
TrackerIdentifier Absorber
Collision vertex range
Collision
Muon HadronAbsorber
Symbols
Detector
-measurement, sources
1
1 : Hadrons, interacting and absorbed (98%),
3
3 : Hadrons, penetrating and interacting (“stopped”)
4
4 : Hadrons, “punch-through”, 5 : Prompt ,”desired signal”
5
2
2 : Charged /K's, “decaying into ” before absorber (≤1%),
PRELIMINARY
Generator ( Decay + punch-through )1. Light hadron measurement by PHENIX central arm (y = 0)2. Gaussian extrapolation in rapidity to muon arm acceptance
( = 2.5)3. Simplified spectrometer geometry.
-measurement,-measurement, Signal composition Signal composition
Forward prompt Forward prompt -- production production (PHENIX) (PHENIX)
PPG057 : PRD76, 092992(2007)
Leptons from Leptons from heavy flavor, heavy flavor, PHENIXPHENIX
PHENIX Preliminary
PRL, 98, 172301 (2007)
Systematically higher than FONLL calculation
Integral e yield follows binary scaling, strong high pT suppression at central AuAu collisions
p+p 200GeV/c
20
Leptons from Leptons from heavy flavor,heavy flavor, STAR STAR
STAR Preliminary
• Combined fit of , D0, low pT e
• Low pT muon constrains charm cross-section
High pT electrons (EMC trigger) FONLL * 5 p+p spectra
STAR high pSTAR high pTT non-photonicnon-photonic electrons electrons
STAR
Phys. Rev. Lett. 98 (2007) 192301
Bottom contribution to Bottom contribution to non-photonic enon-photonic e
Data consistent with FONLL.
(b
e)/(
ce+
b
e)
Results at higher energyResults at higher energy
Differential charm cross sectionDifferential charm cross section
Differential bottom cross sectionDifferential bottom cross section
A question?A question?
• STAR high pT electrons?STAR high pT electrons?
• If it’s problem, normalization (efficiency)?If it’s problem, normalization (efficiency)?– Detector thickness must be varying a lot!Detector thickness must be varying a lot!