measurements of open heavy-flavour production in pp and p ......t-differential production cross...
TRANSCRIPT
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Measurements of open heavy-flavour production in pp and p-Pb collisions with ALICE
Sarah LaPointe INFN Torino
For the ALICE collaboration
The 7th international workshop on charm physics May 18-22, 2015
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Why study open heavy flavour?
(GeV)s10 210 310 410
b)µ ( cc
σ
10
210
310
410ALICE (total unc.)ALICE extr. unc.ATLAS Preliminary (total unc.)ATLAS extr. unc.LHCb Preliminary (total unc.)PHENIXSTARHERA-B (pA)E653 (pA)E743 (pA)NA27 (pA)NA16 (pA)E769 (pA)NLO (MNR)
ALI−PUB−15089
JHEP 1207 (2012) 191
(GeV)s
210 310 410
b)
µ/d
y (
bb
σd
1
10
210= 2.76 TeV, |y|
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Why study open heavy flavour?
‣ Study cold nuclear matter effects, to better evaluate hot matter effects in Pb-Pb collisions
‣ Modification of parton distributions in nuclei
‣ shadowing / gluon saturation at low Bjorken x
‣ kT-broadening from multiple soft scatterings
‣ Study partonic energy loss from initial- and final-state radiation
‣ Investigate potential final-state effects
S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 3
JHEP 0904(2009) 65
p-Pb collisions
Results from Pb-Pb collisions C. Bianchin (this session)Experimental overview ➜ A. Dainese (this morning)
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A Large Ion Collider Experiment
TOF - PID w/ Time Of Flight
TPC - Tracking and PID w/ dE/dx
Muon spectrometer - Trigger, tracking, and
PID
ITS - Trigger, event topology, tracking, PID
Central barrel |η|
-
dE/dxσe〉dE/dx〈dE/dx -
-10 -8 -6 -4 -2 0 2 4 6 8 10
E/p
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
1
10eK+p π
15/05/2012
=2.76 TeVspp
EMCal Trigger Events
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Heavy-flavour production cross sections
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 6
• pQCD predictions describe the data within uncertainties FONLL: JHEP 1210 (2012) 37, GM-VFNS: EPJ C72 (2012) 2082, kT-factorization: PRD 87 (2013) 094022
• Measurements of HF-decay electrons complementary to the high-pT ATLAS result• Similar situation for pp collisions at √s = 2.76 TeV
GeV/c t
p0 5 10 15 20 25
b/G
eV
/c)
µ
(|y
|<0.5
| t /
dp
σd
-210
-110
1
10
210
310
ALICE-1 = 5 nb
int = 7 TeV, Ls, pp
+D
2.1% BR norm. unc. (not shown)± 3.5% lumi, ±
stat. unc.
syst. unc.
FONLL
GM-VFNS
(GeV/c)t
p0 5 10 15 20 25
FO
NL
LD
ata
00.5
1
1.52
2.53
3.5
(GeV/c) t
p0 5 10 15 20 25
GM
-VF
NS
Data
00.5
11.5
22.5
33.5
ALI−PUB−12507
JHEP 1201 (2012) 128, Ds in PLB 178 (2012) 279
)2
dy)
(m
b/(
GeV
/c)
t/(
dp
σ2
) d
tp
π 1
/(2
-910
-810
-710
-610
-510
-410
-310
-210
-110
e→ALICE c, b
e→ATLAS c, b
e, |y| < 0.5→FONLL c, b
e, |y| < 2 excl. 1.37 < |y| < 1.52→FONLL c, b
= 7 TeVspp,
(GeV/c)t
p
-110×4 1 2 3 4 5 6 7 8 910 20 30
Data
/FO
NLL
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
ALI−PUB−16461
ALICE: PRD 86 (2012) 11200 ATLAS: PLB 707 (2012) 438
PLB 708 (2012) 265
pp collisions at √s = 7 TeVD mesons
HF-decay muonsHF-decay electrons
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S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 7
• pT-differential production cross section of electrons from beauty-hadron decays
• Compatibility with FONLL, GM-VFNS and kT-factorization calculations )
2 )c
dy)
(m
b/(
GeV
/T
p/(
dσ
2)
dT
pπ
1/(
2
-810
-710
-610
-510
-410
-310
-210 = 2.76 TeVsALICE pp,
1.9% normalization uncertainty not shown
(a)
e→ c) →b (
data
FONLL factorizationT k
GM-VFNS
Da
ta/T
he
ory
0.51
1.52
2.53
FONLL(b)
Da
ta/T
he
ory
0.51
1.52
2.53
(c) -factorizationTk
)c (GeV/T
p 0 2 4 6 8 10
Data
/Theory
0.51
1.52
2.53
(d)GM-VFNS
ALI-PUB-82148
PLB 738 (2014) 97-108
Electrons from beauty-hadron decays N
orm
aliz
ed
co
un
ts (
a.u
.)
1
10
210
310
PYTHIA e→ c) →b (
e→c Conversions (V0)Dalitz decays
DataConversions (V0)
= 2.76 TeVsALICE pp,
(a)
m)µ (0 d-600 -400 -200 0 200 400 600
Da
ta/M
C
00.5
11.5
22.5
3 Conversions (V0) (b)
ALI-PUB-82084
-3 -2 -1 0 1 2 3
)-1
(r
ad
e-h
)ϕ
∆/d
N (
de
N1/
1
1.5
2
2.5
3
3.5
4 (a) MB Trigger Samplec < 2.5 GeV/e
Tp1.5 <
c > 0.3 GeV/hT
p
| < 0.9η|
/NDF = 19/182χ
= 2.76 TeVsALICE pp,
(rad)ϕ∆-3 -2 -1 0 1 2 3
1
2
3
4
5
6
7
8 e→Data: c,b
MC fit
e→MC: c ) e→ (c →MC: b
(b) EMCal Trigger Sample
c < 6.0 GeV/eT
p4.5 <
c > 0.3 GeV/hT
p
| < 0.7η|
/NDF = 8.5 / 92χ
ALI-PUB-82098
• relatively long lifetime (cτ~500 μm) ➜ broad impact parameter distribution• decay kinematics ➜ ∆φ between electron-hadron wider than for other sources
Beauty-hadron decays
FONLL: JHEP 1210 (2012) 37, GM-VFNS: EPJ C72 (2012) 2082, kT -factorization: PRD 87 (2013) 094022
Impact-parameter analysis
electron-hadron azimuthal correlation
pp collisions at √s = 7 TeV
-
(rad)ϕ∆-1 0 1 2 3 4 5
)-1 -
base
line
(rad
ϕ∆da
ssoc
Nd DN1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
scale uncertainty-10%+13%
=7 TeV Data spp =7 TeVsSimulations, pp
Pythia8Pythia6, Perugia2010Pythia6, Perugia2011
baseline uncertainty
D meson - charged particle correlation
ALICE Preliminary| < 1.0 η∆, |c > 1.0 GeV/assoc
Tp, c < 16 GeV/D
Tp8 <
*+,D+,D0Average D
ALI−PREL−78716 (rad)ϕ∆
-1 0 1 2 3 4 5
)-1 -
base
line
(rad
ϕ∆da
ssoc
Nd DN1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
scale uncertainty-10%+13%
=7 TeV Data spp =7 TeVsSimulations, pp
Pythia8Pythia6, Perugia2010Pythia6, Perugia2011
baseline uncertainty
D meson - charged particle correlation
ALICE Preliminary| < 1.0 η∆, |c > 0.5 GeV/assoc
Tp, c < 8 GeV/D
Tp5 <
*+,D+,D0Average D
ALI−PREL−78598
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 8
• Baseline subtracted azimuthal correlation of D mesons and charged hadrons• Different PYTHIA tunes consistent with the measurement• Data from Run-II at the LHC will provide more precision ➜ constrain models
D meson-hadron azimuthal correlationsMeasure the associated hadron yield on the near (∆φ around 0) and away side (∆φ around π)
• Sensitive to quark fragmentation• Insight into cc production mechanisms5 < pTD < 8 GeV/cpTAssoc. > 0.5 GeV/c
8 < pTD < 16 GeV/cpTAssoc. > 1 GeV/c
PYTHIA8Perugia 2010Perugia 2011
pp collisions at √s = 7 TeV
-
〉T
pdy
/dN
2 d〈)
/ T
pdy
/dN
2(d
5
10
15
20
25
c
-
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 10
Multiplicity dependence of D-meson production
Self-normalized D-meson yields as a function of charged-particle multiplicity
〉T
pdy
/dN
2 d〈)
/ T
pdy
/dN
2(d
5
10
15
20
25
c
-
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 11
Multiplicity dependence of D-meson production
Self-normalized D-meson yields as a function of charged-particle multiplicity
〉T
pdy
/dN
2 d〈)
/ T
pdy
/dN
2(d
5
10
15
20
25
c < 2 GeV/T
p 1 < c < 4 GeV/
Tp 2 <
c < 8 GeV/T
p 4 < c < 12 GeV/
Tp 8 <
c < 20 GeV/T
p 12 <
= 7 TeVsALICE, pp |
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S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 12
• Measured for different D-meson species
• Increase of D-meson per-event yield with increasing charged-particle yield
• Within the uncertainties, no pT-dependence of D-meson yield vs. multiplicity observed
• Similar rising trend observed for J/ψ mesons central and forward rapidity PLB 712(2012)165
• Increase of beauty production with increasing multiplicity
Multiplicity dependence of D-meson production
Self-normalized D-meson yields as a function of charged-particle multiplicity
〉T
pdy
/dN
2 d〈)
/ T
pdy
/dN
2(d
5
10
15
20
25
c < 2 GeV/T
p 1 < c < 4 GeV/
Tp 2 <
c < 8 GeV/T
p 4 < c < 12 GeV/
Tp 8 <
c < 20 GeV/T
p 12 <
= 7 TeVsALICE, pp |
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S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 13
• Assessment of initial-state, cold nuclear matter effects
• Investigate possible final-state effects
p-Pb collisions at √s = 5.02 TeV
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S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 14
Nuclear modification factor for HF-decay electrons
• RpPb of HF-decay electrons compatible with unity• Data described by FONLL+EPS09 parametrization of shadowing, within the
uncertainties NPB 373(1992)295, JHEP 0904 (2009) 065• RpPb of electrons from beauty hadron decays is also compatible with unity
(GeV/c)T
p0 2 4 6 8 10 12 14
nucl
ear
modifi
atio
n fact
or
0.5
1
1.5
2
2.5
3
normalization uncertainty
)/2, TPC-TOF, ALICE reference-
+ e+
(e→ALICE b,c
)/2, TPC-EMCal, ALICE reference-
+ e+
(e→ALICE b,c
)/2, TPC-EMCal, FONLL reference-
+ e+
(e→ALICE b,c
FONLL + EPS09 shad.
< 1.06CMS
= 5.02 TeV, min. bias, -0.14 < yNNsp-Pb,
ALI−DER−53763
RpPb =d�pPb/dpT
A ⇥ d�pp/dpT
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S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 15
Nuclear modification factor for HF-decay electrons
• RpPb of HF-decay electrons compatible with unity• Data described by FONLL+EPS09 parametrization of shadowing, within the
uncertainties NPB 373(1992)295, JHEP 0904 (2009) 065• RpPb of electrons from beauty-hadron decays is also compatible with unity
)c (GeV/T
p0 2 4 6 8 10 12 14
pP
bR
0.5
1
1.5
2
2.5
3 e→ALICE b,c
e→ c) →ALICE b (
normalization uncertainty
ALICE Preliminary
< 0.14CMS
y = 5.02 TeV, min. bias, -1.06 < NNsp-Pb,
ALI−PREL−76745
RpPb =d�pPb/dpT
A ⇥ d�pp/dpT
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S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 16
Nuclear modification factor for HF-decay muons
• RpPb of HF-decay muons at forward rapidity compatible with unity• RpPb of HF-decay muons at backward slightly greater than unity at low pT• Data described by models that include cold nuclear matter effects
MNR pQCD calculation with EPS09 parametrization of shadowing NPB 373(1992)295, JHEP 0904 (2009) 065I. Vitev - coherent scattering, kT-broadening, and energy loss in cold nuclear matter PRC 75 (2007) 064906 Z. B. Zhang et. al. - incoherent multiple scattering PLB 740 (2015) 23
)c (GeV/T
p0 2 4 6 8 10 12 14 16
pP
bR
0
0.5
1
1.5
2
2.5 c,b decays←±µ = 5.02 TeV, NNsp-Pb
-
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 17
Nuclear modification factor for D mesons
• RpPb of D mesons compatible with unity within the pT range covered• The RpPb can be described by:
MNR pQCD calculation with EPS09 parametrization of shadowing NPB 373(1992)295, JHEP 0904 (2009) 065I. Vitev - coherent scattering, kT-broadening, and energy loss in cold nuclear matter PRC 75 (2007) 064906 CGC - color glass condensate NPA 920 (2013) 78.
)c (GeV/T
p0 5 10 15 20 25
pP
bR
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6 *+, D
+, D
0Average D
-
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 18
Multiplicity dependence of D-meson production
• D-meson production vs. multiplicity ➜ similar trend in pp and p-Pb collisions • pp collisions: high multiplicity events attributed to MPI• p-Pb collisions: high multiplicity events also from multiple binary nucleon-
nucleon collisions • CMS reports similar trend from Υ measurements in pp and p-Pb collisions
〉T
pdy
/dN
2 d〈)
/ T
pdy
/dN
2(d
5
10
15
20
25
= 7 TeVspp, c
-
(rad)ϕ∆-1 0 1 2 3 4 5 6
)-1) (
rad
ϕ∆
/ d
eh) (
dNe
(1 /
N
0.0
0.5
1.0
1.5
2.0 = 5.02 TeVNNsp-Pb,
< 2.0 GeV/ceT
1.0 < p
< 2.0 GeV/chT
0.5 < p
(e from c,b)-h correlation
| < 1.6η∆| < 0.9, |η|
-1Global normalization uncertainty = 0.06 rad
p-Pb, V0A Multiplicity class: 0 - 20 %p-Pb, V0A Multiplicity class: 20 - 60 %p-Pb, V0A Multiplicity class: 60 - 100 %Syst. on ped. estimationSyst. from secondary particles
= 7 TeVspp, pp, stat. uncertainty
ALI−PREL−61949
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 19
HF electron-hadron correlations in p-Pb collsions
(rad)ϕ∆ -1 0 1 2 3 4
)-1 (r
adη
∆) p
er
ϕ∆
/ d
h) (
dNe
(1 /
N
3.0
3.1
3.2
3.3
3.4
= 5.02 TeVNNsp-Pb,
(0-20%) - (60-100%), Multiplicity Classes from V0A
< 2.0 GeV/ceT
1.0 < p
< 2.0 GeV/chT
0.5 < p
| < 1.6η∆| < 0.9, |η|
(e from c,b)-h correlation
-1Global normalization uncertainty = 0.022 rad
ALI−PREL−62034
(0-20%)-(60-100%)
(rad)ϕ∆-1 0 1 2 3 4 5 6
)-1) (
rad
ϕ∆
/ d
eh) (
dNe
(1 /
N
0.0
0.5
1.0
1.5
2.0
2.5
3.0 = 5.02 TeVNNsp-Pb,
< 4.0 GeV/ceT
2.0 < p < 2.0 GeV/ch
T0.5 < p
(e from c,b)-h correlation
| < 1.6η∆| < 0.9, |η|
-1Global normalization uncertainty = 0.11 rad
p-Pb, V0A Multiplicity class: 0 - 20 %p-Pb, V0A Multiplicity class: 20 - 60 %p-Pb, V0A Multiplicity class: 60 - 100 %Syst. on ped. estimationSyst. from secondary particles
= 7 TeVspp, pp, stat. uncertainty
ALI−PREL−61956
1 < ptriggerT < 2 GeV/c 2 < ptriggerT < 4 GeV/c
In high multiplicity events:At low electron pT a hint of near- and away-side enhancement
Remove jet contribution by subtracting low multiplicity events
Indication for double-ridge structure, as observed for light-flavor two particle correlations. PLB 719 (2013) 29, PLB 726 (2013) 164
HF possibly affected by the processes consistent with long-range correlations in ∆η of light-flavour hadrons
Initial state: CGC arXiv:1302.7018Final state: Hydrodynamics PLB 718 (2013) 1557
(rad)
ϕ∆ -1
01
23
4
η∆ -1.5
-1.0-0.5
0.00.5
1.01.5
)-1
) (ra
dϕ
∆dη∆
/ d
hN2) (
de
(1 /
N
3.0
3.1
3.2
= 5.02 TeVNNsp-Pb, (0-20%) - (60-100%), Multiplicity Classes from V0A(e from c,b)-h correlation
< 2.0 GeV/ceT
1.0 < p < 2.0 GeV/ch
T0.5 < p
ALI−PREL−62026
(0-20%)-(60-100%)
— pp √s = 7 TeVp-Pb multiplicity classes0-20%20-60%60-100%
For all: 0.5
-
(rad)ϕ∆-1 0 1 2 3 4 5
)-1
- b
ase
line (
rad
ϕ∆
d
ass
oc
Nd
DN1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
scale uncertainty p-Pb-9%+12%
scale uncertainty pp-10%+13%
=7 TeVspp
=5.02 TeVNN
sp-Pb baseline uncertainty pp
baseline uncertainty p-Pb
D meson - charged particle correlation
ALICE Preliminary
| < 1.0 η∆, |c > 0.5 GeV/assocT
p, c < 8 GeV/DT
p5 <
*+,D+,D0Average D
ALI−PREL−79970
(rad)ϕ∆-1 0 1 2 3 4 5
)-1
- b
ase
line (
rad
ϕ∆
d
ass
oc
Nd
DN1
-0.5
0
0.5
1
1.5
2
2.5
3
3.5
4
scale uncertainty-9%+12%
=5.02 TeV Data NN
sp-Pb
=5.02 TeVsSimulations, pp Pythia8Pythia6, Perugia2010Pythia6, Perugia2011
baseline uncertainty
D meson - charged particle correlation
ALICE Preliminary
| < 1.0 η∆, |c > 0.5 GeV/assocT
p, c < 16 GeV/DT
p8 <
*+,D+,D0Average D
ALI−PREL−79835
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 20
D meson-hadron correlations in p-Pb collisions
Azimuthal correlation of D mesons with charged hadrons in pp and p-Pb collisions
5 < pTD < 8 GeV/c, pTAssoc. > 0.5 GeV/c 8 < pTD < 16 GeV/c, pTAssoc. > 0.5 GeV/c
• Distributions from pp and p-Pb collisions are comparable• Within the uncertainties the p-Pb measurement is consistent with various PYTHIA tunes • Better constraints of PYTHIA tunes with improved statistics available in Run-II at the LHC
-
S. LaPointe Charm: The 7th international conference on charm physics 2S. LaPointe Charm 2015: The 7th International Workshop on Charm Physics 21
Summary and outlookpp collisions• Measured production cross sections allow us to test various pQCD predictions
• FONLL, GM-VFNS, kT-factorization predictions are in agreement with data• Heavy quark fragmentation studies via D-meson azimuthal correlations
• Consistent with various PYTHIA tunes• Heavy-flavour hadron yield vs. multiplicity
• With increasing multiplicity, yield increases more than linearly • Models including MPI contributions reproduce the observed trend
p-Pb collisions• Heavy-flavour hadron yields
• No strong suppression observed with respect to pp collisions• Increasing yields with increasing event multiplicity, as observed in pp collisions
• D-meson azimuthal correlations• Consistent with various PYTHIA tunes
• Electron-hadron azimuthal correlations at low pT• Double-ridge structure observed. CGC, hydrodynamic expansion, some other mechanism?
Outlook• Statistically larger data sample from Run-II at the LHC• More precise measurements of azimuthal correlations, beauty, and heavy flavour in jets
-
Extras
-
QpPb dependence of event activity
) c (GeV/T
p 0 5 10 15 20 25 30
pro
mpt D
mu
lt
pP
bQ
0
0.5
1
1.5
2
2.5
3
0-20%
20-40%
40-60%
60-100%
ALICE Preliminary = 5.02 TeV
NNsp-Pb,
Filled markers : pp rescaled reference-extrapolated reference
TpOpen markers: pp