heavy quarks at the lhc
DESCRIPTION
Heavy Quarks at the LHC. Andrea Dainese INFN Legnaro (ALICE Collaboration). Layout. Heavy-flavour production in hadronic collisions pp baseline: pQCD calculations nuclear effects, in initial and final state What have we learnt at Tevatron and RHIC? What will be new at the LHC? - PowerPoint PPT PresentationTRANSCRIPT
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 1
Heavy Quarks Heavy Quarks at the LHCat the LHC
Heavy Quarks Heavy Quarks at the LHCat the LHC
Andrea DaineseAndrea Dainese
INFN LegnaroINFN Legnaro(ALICE Collaboration)(ALICE Collaboration)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 2
LayoutLayoutHeavy-flavour production in hadronic collisions
pp baseline: pQCD calculations
nuclear effects, in initial and final state
What have we learnt at Tevatron and RHIC?
What will be new at the LHC?
What do we expect?
What should we measure?
Experimental Perspectives at the LHC
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 3
Heavy-flavour production: ppHeavy-flavour production: ppproton-proton collisions: factorised pQCD approach
)pp(zDp
xPDFxPDF cDDccT
c
/d
ˆd)()( 21
)~Q~( 2221 ccMsxx
s /2
c
c D
D
x1
x2
Q2
s /2),(d
dRFD
T
D
p
PDF:• Q2 evolution calculated in pQCD• initial condition from data (HERA)
FF: • non-perturbative • phenomenolgy + fit to data (e+e-)
calculable as perturbative series of strong coupling s(R)
22, Q~RF
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 4
pp QQ+X: pQCD calculations vs datapp QQ+X: pQCD calculations vs data
Calculation of partonic cross section classic: Fixed Order (NLO) Massive (e.g. MNR code)
state-of-the-art: Fixed Order Next-to-Leading Log (FONLL)
Tp
more accurate at high pT
FONLL: Cacciari, Frixione, Mangano, Nason and Ridolfi, JHEP0407 (2004) 033
B production at Tevatron (1.96 TeV)is well described by FONLL
CDF, PRL91 (2003) 241804FONLL: Cacciari, Nason
Charm production slightly underpredictedat Tevatron (1.96 TeV)
Cacciari, Nason, Vogt, PRL95 (2005) 122001
& at RHIC (200 GeV)Q e+X
latest update in the following
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 5
Heavy-flavour production: AAHeavy-flavour production: AA
A
A
Binary scaling for hard yields: collDT
Dpp
DT
DAA NpNpN d/dd/d
Binary scaling is “broken” by:
c
c D
D
x
fgPb / fg
p
LHC RHIC SPSRAA <1 ~1 >1
Q2 = 5 GeV2
pT
RA
B
1
~2-4 GeV/c
kL kT
Cronin enhancement
• initial-state effects: PDF shadowing kT broadening (‘Cronin’)
medium formed in the collision
A
A c
cD
Du
• final-state effects energy loss? [next slide]
in-medium hadronization (recombination?)
recombination: pH = pq
fragmentation: pH = z pq
baryon/meson enhancement
Calculating Parton Energy LossCalculating Parton Energy Loss
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 6
cc
ccRsC
I
for )/(
for /
d
d2
Baier, Dokshitzer, Mueller, Peigné, Schiff, NPB 483 (1997) 291.Zakharov, JTEPL 63 (1996) 952.Salgado, Wiedemann, PRD 68(2003) 014008.
BDMPS-Z formalismpath length L
kT
Radiated-gluon energy distrib.:
2
ˆTk
q transport coefficient
2/ˆ 2Lqc LR c
sets the scale of the radiated energyrelated to constraint kT < , controls shape at << c
Casimir coupling factor: 4/3 for q, 3 for gRC
(BDMPS case)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 7
Models vs RHIC “light” dataModels vs RHIC “light” dataModel: pQCD + E loss probability + detailed collision geometry
Density ( ) “tuned” to match RAA in central Au-Au at 200 GeV
/fmGeV 144ˆ 2q
q
matches pT-indepence of suppression at high pT
Dainese, Loizides, Paic, EPJC 38 (2005) 461.
(Quark Matter 05)
Same theoretical calculation (SW quenching weights) and similar results in Eskola, Honkanen, Salgado, Wiedemann, NPA747 (2005) 511
Tpp
TAA
collTAA dpdN
dpdN
NpR
/
/1)(
PRL101 (2008) 232301
Lower E loss for heavy quarks ?Lower E loss for heavy quarks ?
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 8
In vacuum, gluon radiation suppressed at < mQ/EQ
“dead cone” effect
Dead cone implies lower energy loss (Dokshitzer-Kharzeev, 2001):• energy distribution d/d of radiated gluons suppressed by angle-
dependent factor
suppress high- tail
Q
Dokshitzer, Khoze, Troyan, JPG 17 (1991) 1602.Dokshitzer and Kharzeev, PLB 519 (2001) 199.
1
1d
d
d
d2
2
2
Q
Q
E
mII
LIGHTHEAVY
Dokshitzer
22QQ
2 ])/([
1
Em
Gluonsstrahlung probability
R = 105
Detailed massive calculation confirms this qualitative feature
(Armesto, Salgado, Wiedemann, PRD 69 (2004) 114003)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 9
Heavy-flavour electrons at RHIC(pp baseline)
Heavy-flavour electrons at RHIC(pp baseline)
FONLL calculation: Cacciari, Nason, Vogt, PRL95 (2005) 122001Drell-Yan from: Gavin et al., hep-ph/9502372Comparison: Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326
FONLL: electron spectrum may be ~50% c + ~50% b for 3 < pT < 8 GeV
Drell-Yan component? < 10% up to 10 GeV
Large uncertainty on b/c crossing point in pT: from scales/masses variation it changes from 3 to 9 GeV
PHENIX electron cross section in pp now quite OK also at high pT
PHENIX hep-ex/0508034
PHENIX, hep-ex/0609010
QM06
?
QM06
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 10
RAA of c and b electrons at RHICRAA of c and b electrons at RHIC
Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326,
Due to large mass of b quark, theory: electron RAA~0.4
Final data: electron RAA ~ pion RAA ~0.2 at high pT
c
b
c+b
PRL 98, 172301 (2007)
e± from heavy flavor
Djordjevic, Gyulassy, Wicks, nucl-th/0512076
STAR Phys. Rev. Lett. 98 (2007) 192301
PHENIX Phys.Rev.Lett.98 (2007) 172301
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 11
RAA of c and b electrons at RHICRAA of c and b electrons at RHIC
C. Salgado, CERN Heavy Ion Forum, Dec 08
Similar results from recent multi-observable 2-analysis including hydro evolution
c+b
c only
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 12
QM06RAA of c and b electrons at RHICRAA of c and b electrons at RHIC
nucl-ex/0611018nucl-ex/0611018
(Adil & Vitev)
Other approaches: include elastic E loss (Djordjevic, Gyulassy, Wicks)
collisional dissociation of D/B mesons formed in the medium early after hard scattering (Adil & Vitev)
What have we learnt from Tevatron and RHIC?What have we learnt from Tevatron and RHIC?
Tevatron: c and b production relatively well understood (b better than c...)
theory: leading log resummation (FONLL); parton shower matched to NLO (MC@NLO); accurate treatment of fragmentation (Cacciari et al.: matching of pert. hat and non-pert. fragm. from ee to pp)
experiment: exclusive (or less inclusive) is better (D mesons, BJ/+X), publish what you measure (not only extrapolations)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 13High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 13
CDF, PRL91 (2003) 241804FONLL: Cacciari, Nason
OK? what if we find the same in pp@14TeV? how do we get a realible reference for [email protected]?
What have we learnt from Tevatron and RHIC?What have we learnt from Tevatron and RHIC?
RHIC: heavy-quark (non-phot.) electrons as suppressed as pions, and they do flow (v2, see later)
but the picture is not clear...pp baseline at upper limit of FONLL band (like CDF’s charm)
suppression not understood (small b contribution? large b E loss?)
Need for dedicated detectors (Si trackers) RHIC-II, LHC
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 14High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 14
CDF, PRL91 (2003) 241804FONLL: Cacciari, Nason
PHENIX, hep-ex/0609010
c
b
c+b
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 15
LayoutLayoutHigh-pT (heavy-flavour) particle production in hadronic collisions –from pp to AA– in factorized QCD
pp baseline: pQCD calculations
nuclear effects, in initial and final state
What have we learnt at Tevatron and RHIC?
What will be new at the LHC?
What do we expect?
What should we measure?
Experimental Perspectives at the LHC
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 16
Novelties at LHC (1): Hard ProbesNovelties at LHC (1): Hard ProbesLHC: large hard cross sections!
Our set of “tools” (probes) becomes richer
quantitatively: qualitatively:• heavy quarks
• + jet correlations• Z0 + jet correlations
bbRHIC
bbLHC
ccRHIC
ccLHC
100
10
LO pQCD by I. Vitev,hep-ph/0212109
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 17
Heavy-quark production at the LHCHeavy-quark production at the LHCpp: Important test of pQCD in a new energy domain
Remember the “15-years saga of b production at Tevatron”*
Baseline predictions: NLO (MNR code) in pp + binary scaling (shadowing [EKS98] included for PDFs in the Pb)
e.g. ALICE baseline for charm / beauty: system :
sNN :Pb-Pb (0-5% centr.)
5.5 TeV
p-Pb (min. bias)
8.8 TeV
pp
14 TeV
4.3 / 0.2 7.2 / 0.3 11.2 / 0.5
115 / 4.6 0.8 / 0.03 0.16 / 0.007
0.65 / 0.80 0.84 / 0.90 --
[mb] QQNN
QQtotN
Theoretical uncertainty of a factor 2—3 (next slide)* M.ManganoMNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295.
98EKSshadowingC
LHC startup at s = 10 TeV?yields lower by 25%
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 18
Theoretical Uncertainties(HERA-LHC Workshop)
Theoretical Uncertainties(HERA-LHC Workshop)
MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295.
Evaluation of theoretical uncertainties
beautycharm
MRST2001 CTEQ6, CTEQ5, CTEQ4, :PDFs
0.0040.0002 2/5.0 GeV 0.55.4
0.110.002 2/5.0 GeV 8.13.1 ,
bRFb
cTRFc
m
mm
CERN/LHCC 2005-014hep-ph/0601164
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 19
Model Comparisons(HERA-LHC Workshop)
Model Comparisons(HERA-LHC Workshop)
Compare predictions by several different models
beautycharm
CERN/LHCC 2005-014hep-ph/0601164+ updates (R.Guernane)
General agreement between collinear factorisation based calculations: FO NLO, FONLL, POWHEG, MC@NLO
problem with POWHEG charm?kT factorization (LO MC CASCADE) higher at large pT
VFNS lower at high pT
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 20
Energy extrapolation via pQCD?Energy extrapolation via pQCD?
Different systems (pp, p-Pb, Pb-Pb) will have different s values
Results in pp at 14 TeV will have to extrapolated to 5.5 TeV (Pb-Pb energy) to compute, e.g., nuclear modification factors RAA
pQCD: there ratio of results at 14 TeV/5.5 TeV has ‘small’ uncertainty
charm beauty
12% 8%
MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295.
Need to define a strategy!
Anyway, difficult to have pp reference at 5.5 TeV
(only 1 month limited stats, pT reach)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 21
increasing s
Probe unexplored small-x region with HQs at low pT and/or forward y
down to x~10-4 with charm already at y=0
Window on the rich phenomenology of high-density PDFs:
gluon saturation / recombination effects
Novelties at LHC (2): Small xNovelties at LHC (2): Small x
ccgg
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 22
Probing small-x gluons with HQs (pp) Probing small-x gluons with HQs (pp)
Large pQCD uncertainties for charm pT0
onset of saturation ?
Two attempts to include non-linear
terms in evolution equationsDGLAP+GLRMQ
BK
indicate charm as a sensitive probe in pp
Eskola et al., NPB660 (2003) 211
Kutak, Kwiecinski, Martin, Stasto
BK: Charm suppression due to non-linear effects
DGLAP: Charm enhancementdue to non-linear effects (GLR-MQ term)
|y| < 1
c(DGLAP+non-linear)c(DGLAP)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 23
Probing small-x gluons with HQs (nuclei)Probing small-x gluons with HQs (nuclei)
Shadowing in pA (AA)
CGC in pA (AA)
Double parton scattering in pA
)/( ppNpPbR collDpPb
c
c
Effect of shadowing on D meson nuclear modification factors at LHC:RAB(pT0) ~ RG
A*RGB at x ~ 2mc/√s ~ 10-3, Q2 ~ 4mc
2 ~ 9 GeV2
EKS98: 0.55 for Pb-Pb at 5.5 TeV 0.75 for p-Pb at 8.8 TeV
EKS98:Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61
€
RGPb (x)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 24
Probing small-x gluons with HQs (nuclei)Probing small-x gluons with HQs (nuclei)
Shadowing in pA (AA)
CGC in pA (AA)
Double parton scattering in pA
)/( ppNpPbR collDpPb
c
c
Effect of shadowing on D meson nuclear modification factors at LHC:RAB(pT0) ~ RG
A*RGB at x ~ 2mc/√s ~ 10-3, Q2 ~ 4mc
2 ~ 9 GeV2
EKS98: 0.55 for Pb-Pb at 5.5 TeV 0.75 for p-Pb at 8.8 TeVEPS08: 0.4 for Pb-Pb at 5.5 TeV 0.6 for p-Pb at 8.8 TeV
EPS08: Eskola, Paukkunen, Salgado, JHEP0807 (2008) 102
to be computed rigorously,
including pT dependence
to be computed rigorously,
including pT dependence
€
RGPb (x)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 25
Shadowing in pA (AA)
CGC in pA (AA)
Double parton scattering in pA
Saturation scale Qs2(x) ~ xg(x)A/RA
2 ~ xg(x)A1/3
At LHC for x~10-4, Qs~1.5-2 GeV > mc
For mT,c~Qs, charm prod. CGC-dominated:• scales with Npart in pA (not Ncoll)• harder pT spectra, since typical kT~Qs~1.5 GeV, while in standard factorization kT~QCD~0.2 GeV
Probing small-x gluons with HQs (nuclei)Probing small-x gluons with HQs (nuclei)
c
c
Kharzeev, Tuchin, NPA 735 (2004) 248 + LHC Predictions Workshop
CGC: very similar RpA for , D, B, ~indep. of pT and rapidity
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 26
Shadowing in pA (AA)
CGC in pA (AA)
Double parton scattering in pA
probe “many-body” PDFs
normal and anomalous: different A dep.
signature: events with “tagged” DD (can use D0+e+ or e+e+) and ch. conj.NB: there is a “background” from normal bb events, but it can be estimated from measured single inclusive b cross section
predicted rate: cccc/cc ~ 10% (Treleani et al.)
Probing small-x gluons with HQs (nuclei)Probing small-x gluons with HQs (nuclei)
c
c
Cattaruzza, Del Fabbro, Treleani, PRD 70 (2004) 034022
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 27
Heavy Quark Energy Loss at LHCHeavy Quark Energy Loss at LHC
~100 cc pairs and ~5 bb pairs per central Pb-Pb collision
Experiments, with high precision trackers, will measure RAA
for D and B, or for their decay leptons
What can we learn from a comparative quenching study of
massive and massless probes at the LHC?
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 28
Heavy Flavour RAA at LHCHeavy Flavour RAA at LHCBaseline: PYTHIA, with EKS98 shadowing, tuned to reproduce c and b pT distributions from NLO pQCD (MNR)
(m/E)-dep. E loss with
MNR: Mangano, Nason, Ridolfi, NPB 373 (1992) 295.
/fmGeV 10025ˆ7ˆ 2* RHICLHC qq
Armesto, Dainese, Salgado, Wiedemann, PRD 71 (2005) 054027. * EKRT Saturation model:Eskola, Kajantie, Ruuskanen, Tuominen, NPB 570 (2000) 379.
(EKS98)(EKS98)
EPS08(guess)
EPS08(guess)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 29
Colour-charge and mass dep. of E loss with Heavy-to-Light ratios at LHC
Colour-charge and mass dep. of E loss with Heavy-to-Light ratios at LHC
Heavy-to-light ratios:
Compare g h , c D and b B
)()()( )(/)( t
hAAt
BDAAthBD pRpRpR
gq EE mass effect
For 10 < pT < 20 GeV, charm behaves like a m=0 quark,light-flv hadrons come mainly from gluonsRD/h enhancement probes colour-charge dep. of E lossRB/h enhancement probes mass dep. of E loss
Armesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 30
LHC: Beauty-to-Charm ratio RB/DLHC: Beauty-to-Charm ratio RB/D
Compare c and b: same colour charge
Mass effect Enhancement of factor ~2, independent of (for )
)()()(/ tDAAt
BAAtDB pRpRpR
q/fmGeV 20ˆ 2q
Adapted from Armesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 31
Beauty energy loss:W-decay muons as a reference
Beauty energy loss:W-decay muons as a reference
Conesa del Valle, Dainese, Ding, Martinez, Zhou, PLB663 (2008) 202
early measurement for all experiments at the LHC!
single RCP(pT)
medium-sensitive and medium-blind probe in same measurement
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 32
Other predictions for RAA at LHCOther predictions for RAA at LHC
Vitev, Adil, “Last Call for LHC Predictions” workshop, 2007
Wicks, Gyulassy, “Last Call for LHC Predictions” worksho, 2007
Radiative+Collisional E lossà la GLV
D
B
D+B
D and B meson formation and dissociation inside the medium
similar to prediction from Armesto et al.
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 33
Charm in-medium hadronization: probe of QGP properties?
Charm in-medium hadronization: probe of QGP properties?
Yields of charm hadrons within statistical hadronization model
Rafelski, Kuznetsova, LHC Predictions Workshop 07
Ratio D/Ds as a probe of T at measured s/S
(PYTHIA: 6.92!)
0.13PYTHIA: 0.19
Braun-Muntzinger, Stachel, LHC Predictions Workshop 07
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 34
Azimuth. asymmetry: v2 from flowAzimuth. asymmetry: v2 from flow
c: 15-20%
b: 5%
van Heese, Rapp, Greco, LHC Predictions Workshop 07
v2 of D and B mesons in non-central collisions tests:
at low/moderate pT: recombination scenario, flow of c/b quarks (?), hence degree of thermalization of medium
Model: mult. scattering in expanding QGP ( elliptic flow)
hadronization via coalescence + fragmentation
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 35
Azimuth. asymmetry: v2 from E lossAzimuth. asymmetry: v2 from E lossv2 of D and B mesons in non-central collisions tests
at higher pT: path-length dependence of E loss in almond-shaped medium
Model: Radiative E loss (BDMPS)
RHIC
Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326 + LHC Predictions Workshop 07
c: 5-10%
LHC
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 36
LayoutLayoutHigh-pT (heavy-flavour) particle production in hadronic collisions –from pp to AA– in factorized QCD
pp baseline: pQCD calculations
nuclear effects, in initial and final state
What have we learnt at Tevatron and RHIC?
What will be new at the LHC?
What do we expect?
What should we measure?
Experimental Perspectives at the LHC
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 37
Tracker TPC (>100) + Si (6) Si (11) Si (16)
Pixel layers
Inner radius
Pixel cell (rx z)
2
4 cm
50x425 m2
3 (+ 6 endcaps)
5 cm
50x400 m2
3 (+ 6 endcaps)
4.3 cm
100x150 m2
Si thickness (x/X0) 7% 30% 20%
d0 res at 1 (10) GeV/c
60 (15) m 80 (15) m 80 (15) m
B field (T) 0.5 2 4
Muon ID -4<<-2.5, pT>1 GeV ||<2.4, pT>3 ||<2.4, pT>3.5
Electron ID ||<0.9, “ ||<2.5, pT>? ||<3, pT>10
Heavy flavour capabilities:tracking, vertexing, lepton IDHeavy flavour capabilities:
tracking, vertexing, lepton ID
d0trackprimary
vertex
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 38
Heavy-flavour capabilities:acceptances & tracking resolutions
Heavy-flavour capabilities:acceptances & tracking resolutions
ALICE(c/b)
ATLAS/CMS(b) LHCb
(b)
-2 0 2 4 61
10
100
1 year pp 14 TeV @ nominal lumin.
pT
of
Q-h
ad
ron
[G
eV]
of Q-hadron
ALICE(b)(c)
ALICE(c/b)
ATLAS/CMS(b) LHCb
(b)
-2 0 2 4 61
10
100
1 year pp 14 TeV @ nominal lumin.
pT
of
Q-h
ad
ron
[G
eV]
of Q-hadron
ALICE(b)(c)
ALICE(c/b)
ATLAS/CMS(b) LHCb
(b)
-2 0 2 4 61
10
100
1 year pp 14 TeV @ nominal lumin.
pT
of
Q-h
ad
ron
[G
eV]
of Q-hadron
ALICE(b)(c)
ALICE(c/b)
ATLAS/CMS(b) LHCb
(b)
-2 0 2 4 61
10
100
1 year pp 14 TeV @ nominal lumin.
pT
of
Q-h
ad
ron
[G
eV]
of Q-hadron
ALICE(b)(c)
HERA-LHC WorkshopCERN/LHCC 2005-014hep-ph/0601164
A.Dainese (ALICE)M.Smizanska (ATLAS)
C.Weiser (CMS)U.Uwer (LHCb)
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 39
Open heavy-flavour in ALICEOpen heavy-flavour in ALICE
D0 K D+ K Ds KK D* D0 D0 K c Kp
understudy
B e+X B +X B 5 pr. B J/ee
understudy
D0K in Pb-PbD+K in pp
Be +X in Pb-Pb
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 40
Heavy-to-light ratios in ALICEHeavy-to-light ratios in ALICE
1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)
)()()(/ thAAt
DAAthD pRpRpR probes colour-charge dep.
of QCD energy loss
€
RB / D (pt ) = RAAe from B(pt ) RAA
e from D(pt )
probes mass dep.of QCD energy loss
E loss calc.: Armesto, et al.Predictions also by Wicks, et al.
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 41
SummarySummaryLHC: heavy quarks factory!Heavy quarks as probes of high-density QCD
low pT: probe small-x structure of p and nucleus
intermediate pT: probe medium thermalisation (reco/flow) high pT: probe medium density via energy loss
pPb reference neededcan we live without pp at the Pb-Pb energy?
Experiments getting ready all crucial detectors (Si trackers, lepton ID) already commissionedthorough calibration and alignment with cosmic runs
Stray particle from LHC beam2 interacts in ALICE pixels [Sept 11, 08]
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 42
Hard Probes 2006 - Asilomar, 15.06.06 Andrea Dainese
442 days to LHC startup!
Hard Probes 2008 14.06.08 Andrea Dainese
ISMD 2008, DESY Hamburg, 18.09.08 Andrea Dainese
after all, maybe we don’t care too much
about the LHC starting ...
after all, maybe we don’t care too much
about the LHC starting ...
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 43
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 44
EXTRA SLIDESEXTRA SLIDES
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 45
LHC running conditionsLHC running conditions
Ldt = 5.1026 cm-2 s-1 x 106 s
5.1032 cm-2 PbPb run, 5.5 TeV
NPbPb collisions = 2 .109 collisions
Ldt dt = 3.1030 cm-2 s-1 x 107 s
5.1037 cm-2 for pp run, 14 TeV
Npp collisions = 2 .1012 collisions
Muon triggers: ~ 100% efficiency, ~ 1kHz Electron triggers: Bandwidth limitation NPbPb central = 2 .108 collisions
Muon triggers: ~ 100% efficiency, < 1kHz
Pb-PB nominal run pp nominal run
Electron triggers: ~ 50% efficiency of TRD L1 20 physics events per event
Hadron triggers: NPbPb central = 2 .107 collisions
Hadron triggers: Npp minb = 2 .109 collisions
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 46
pair of opposite-charge tracks with large impact parameters
good pointing of reconstructed D momentum to the primary vertexD0
Charm reconstruction: D0 K-+ & D+ K-++
Two vertexing algos with full error-matrix treatment
Large combinatorial background (dNch/dy=6000 in Pb-Pb simul.)
Main selection: displaced-vertex selection
Invariant mass analysis
large distance (dPS) between primary and secondary vertex
good pointing of reconstructed D momentum to the primary vertexD+
1 year at nominal luminosity(109 pp events, 107 central Pb-Pb events)
10
20
30
40
50
D+D0
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 47
Beauty in the barrel:displaced single electrons
Beauty in the barrel:displaced single electrons
PrimaryVertex B
e
Xd0
rec. track
• ALICE has excellent electron identification capabilities (TRD + TPC)
• Displaced electrons from B decays can be tagged by an impact parameter cut
electron
High-density QCD, Santiago de Compostela, 03.02.2009 Andrea Dainese 48
Beauty in the barrel: displaced J/ee
Beauty in the barrel: displaced J/ee
• Standard method for b prod. meas. at the Tevatron• Displaced di-electrons (TPC,TRD) from J/ from B decays
tagged by an impact parameter cut (ITS)
t
Jxy p
ML /
totalbackgroundall J/J/ from B
J/ pseudoproper decay time (pt>0)
in progress
Lxy