heavy quarks in view of the lhc

Frankfurt, 07.12.2006 Andrea Dainese 1

Heavy Quarks Heavy Quarks in view of the LHCin view of the LHC

Andrea DaineseAndrea Dainese

INFNINFN(ALICE Collaboration)(ALICE Collaboration)


LayoutHigh-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

PARTONPARTONENERGYENERGY

LOSSLOSS


Heavy-flavour production: ppproton-proton collisions: factorized 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


pp QQ: pQCD calculations vs data

Calculation of partonic cross section standard: 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

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

QM06 update later


Heavy-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 Loss

cc

ccRsC

I

for )/(

for /

d

d2

Baier, Dokshitzer, Mueller, Peigne‘, 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)


Model 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)(


large RAA indep. of q q

Limited sensitivity of RAA

Strong suppression requires very large density

Surface emission scenario

RAA determined by geometry rather than by density itself

Limited sensitivity to

Need more differential observables:

massive partons

RAA vs reaction plane

study of jet shapes

…

q

Eskola, Honkanen, Salgado, Wiedemann, NPA 747 (2005) 511.

?


Lower E loss for heavy quarks ?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)


Charm RAA at RHIC

effect of the mass

thermalized component

/fmGeV 144ˆ 2q

Small effect of mass for charm (~50% for D, ~30% for e) at low pT [large uncertainties!]Basically no effect in “safe” pT-region

Armesto, Dainese, Salgado, Wiedemann, PRD 71 (2005) 054027.

(extracted from light-flv hadron data)

larger uncertainties

other contributions become important


Charm + beauty + DY electrons at RHIC(pQCD baseline revised, and its uncertainties)

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

We investigated the DY 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 update

?

QM06 update


RAA of c and b electrons at RHIC

Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326,

Due to larger mass of b quark electron RAA increased to ~0.4

Mass uncertainty (in E loss) and scales uncertainty (in pQCD b/c crossing) were studied

c

b

c+b

Theory predicts e RAA (~0.4)

larger than RAA (~0.2) e spectra in principle sensitive to mass hierarchy Perturbative uncertainty on the pp baseline comparable to model-intrinsic uncertainty in determination of

Preliminary STAR data not conclusive for comparison with theory

nucl-ex/0611018

QM06 update

Theory predicts e RAA (~0.4)

larger than RAA (~0.2) e spectra in principle sensitive to mass hierarchy Perturbative uncertainty on the pp baseline comparable to model-intrinsic uncertainty in determination of

Final data (QM06): electron RAA tends to be overestimated

Djordjevic, Gyulassy, Wicks, nucl-th/0512076


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)

QM06 update

RAA of c and b electrons at RHIC

nucl-ex/0611018nucl-ex/0611018

(Adil & Vitev)







What do we expect?




Novelties 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


Heavy-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 included for PDFs in the Pb)

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


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


Model Comparisons(HERA-LHC Workshop)

Compare predictions by several different models

Good agreement between collinear factorization based calculations: FO NLO and FONLLkT factorization (CASCADE) higher at large pT

beautycharm

CERN/LHCC 2005-014hep-ph/0601164


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.


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

Eskola, Kolhinen, Vogt, PLB582 (2004) 157Gotsmann, Levin, Maor, Naftali, hep-ph/0504040

Window on the rich phenomenology of high-density PDFs:

gluon saturation / recombination effects

Possible effect: enhancement of charm production at low pT w.r.t. to standard DGLAP-based predictions, even in pp!

c(DGLAP+non-linear)c(DGLAP)

Novelties at LHC (2): Small x

ccgg


Probing nuclear initial state PDFs with HQs

Shadowing in pA (AA)

CGC in pA (AA)

Double parton scattering in pA

)/( ppNpPbR collDpPb

c

c

Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61



CGC in pA (AA)


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


c

c

Kharzeev, Tuchin, NPA 735 (2004) 248



CGC in pA (AA)


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.)


c

c

Cattaruzza, Del Fabbro, Treleani, PRD 70 (2004) 034022


Heavy Quark Energy Loss at LHC

~100 cc pairs and ~5 bb pairs per central Pb-Pb collision

Experiments will measure with good precision RAA for D and

B, and for their decay leptons (as I’ll show in 5’)

What can we learn from a comparative quenching study of

massive and massless probes at the LHC?


Heavy 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.


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


LHC: 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


Azimuthal asymmetry (v2)Azimuthal asymmetry --v2 or RAA()-- 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

at higher pt: path-length dependence of E loss in almond-shaped medium

= 0

= /2P

HEN

IX

0 v

2

Cole @ Quark Matter 05v2 from E loss: Dainese, Loizides, Paic, EPJC 38 (2005) 461

Armesto, Cacciari, Dainese, Salgado, Wiedemann, PLB637 (06) 326.







What do we expect?




Experimental study of heavy flavours in AA at the LHC

ATLASCMS


Tracker TPC (100) + Silicon (6) Silicon (11) Silicon (16)

Si thickness (x/X0) 7% 30% 20%

B field (T) 0.5 2 4

Tracking & Vertexing

D mesons c ~ 100–300 m, B mesons c ~ 500 m

Secondary vertex capabilities! Impact param. resolution!

PrimaryVertex B

e

Xd0

rec. track


Impact parameter resolution Resolution mainly provided by the layers of silicon pixels

PIXEL CELL

z: 425 m

r: 50 m

Two layers:r = 4 cmr = 7 cm

9.8 MINFN Padova-Legnaro


Tracker TPC (100) + Silicon (6) Silicon (11) Silicon (16)

Si thickness (x/X0) 7% 30% 20%

B field (T) 0.5 2 4

Tracking & Vertexing

D mesons c ~ 100–300 m, B mesons c ~ 500 m

Secondary vertex capabilities! Impact param. resolution!

acceptance: pt > 1 GeV/cr < 50 m for pt > 2.5 GeV/c

pt/pt < 2% up to 100 GeV/c

acceptance: pt > 0.2 GeV/cr < 50 m for pt > 1.5 GeV/c

pt/pt < 2.5% up to 20 GeV/c < 6% up to 100 GeV/c

B = 0.5 TB = 4 T


Lepton and Hadron IDD and B: large B.R. to leptons: ~10% e + ~10%

ALICE:electrons: Transition Rad. + dE/dx in || < 0.9 and pt > 1 GeV/c

+ EM cal (performance under study)muons: -4 << -2.5 and pt >1 GeV/c (use pz to punch through abs.)

CMS (ATLAS):muons: || < 2.4 (3) and pt > 3.5 (4) GeV/c

electrons in EM cal? (no heavy-ion studies yet)

With leptons, difficult to measure D(B) pt distr. and go to low pt (loose pt correlation)

Exclusive hadronic decay channels (charm)

Need PID (kaons!) to reject huge combin. background in AA

ALICE hadron ID: large TPC + high-res TOF + RICH (small acc.)


Charm reconstruction: D0 K-+

Large combinatorial background (dNch/dy=6000 in central Pb-Pb!)

Main selection: displaced-vertex selection pair of opposite-charge tracks with large impact parameters

good pointing of reconstructed D0 momentum to the primary vertex

Invariant mass analysis


Beauty via displaced 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

Expected pt coverage1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)

D0 K B e + X

• should have similar performance • higher pt

min because lack of K id

• should have similar performance, at least with muons• higher pt

min because more material & larger field

CMS & ATLAS


Calibrating the probe (pp, s = 14 TeV)

D0 K B e + X

tpp

tAA

colltAA pN

pN

NpR

d/d

d/d1)( measured at 14 TeV, then

scaled by pQCD to 5.5 TeV

Expected sensitivity in comparison to pQCD:

1 year at nominal luminosity(109 pp events)


tDpp

tDAA

collt

DAA dpdN

dpdN

NpR

/

/1)(

tepp

teAA

collt

eAA dpdN

dpdN

NpR

/

/1)(

Charm and Beauty E Loss : RAA

mb = 4.8 GeV

Low pt (< 6–7 GeV/c)Also nuclear shadowing (here EKS98), in-medium hadr…

High pt (> 6–7 GeV/c)Only parton energy loss

D0 K B e + X

1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)


Heavy-to-light ratios in ALICE

1 year at nominal luminosity(107 central Pb-Pb events, 109 pp events)

)()()(/ thAAt

DAAthD pRpRpR

)()()( D from eB from e/ tAAtAAtDB pRpRpR


Beauty via (forward) muons

inner bars: stat. errorsouter bars: syst. errors

Muons “identified” in the forward spectrometer (-4 << -2.5)

Pb-Pb 0-5%

single muons in the spectrometer:beauty dominates for pt > 2-3 GeV/c


W’s as a medium-blind reference

pQCD predicts b/W crossing at pTmuon ~ 30 GeV/c

In Pb-Pb, b-quark in-medium energy loss would shift crossing to lower pT

Ding, A.D., Zhou, QM06 poster. Conesa, A.D., Ding, Martinez, Zhou, in preparation


J/ from B (à la CDF) in CMS & ALICE

primary J/

J/from B

energy LHCat 2.0~J/ψ all

B from J/ψ

J/ +- J/ e+e-

CMS: CMS/NOTE 2001/008, ALICE: CERN/LHCC 99-13


ConclusionsAt LHC heavy quarks will be produced with large rates

robust tool for the study of QCD in extreme conditions

Heavy-quark phenomelogy promises to be very rich from very low pT: probe small-x structure of p and nucleus to very high pT: probe the QCD medium via energy loss

Excellent “heavy-quark busters” (ALICE, ATLAS, CMS) are being installed at CERN265 days to LHC startup!


Appendix:QUARKONIA at LHC


H.Satz

Quarkonia at LHC: (cc)

J/ suppression & regeneration?

c, ’ suppression (J/ TD ~ 1.5-2 Tc)?Satz, CERN Heavy Ion Forum, 09/06/05

SPSRHICLHC

30

enhanced suppression

enhanced regeneration

TLHC >> J/ TD Wong, PRC 72 (2005) 034906

Alberico, hep-ph/0507084

Becattini, PRL95 (05) 022301

Statistical hadronization: huge enhancements for cc, cc, Bc, ccc

e.g. 1000 for ccc/D from pp to Pb-Pb


productionproduction

RHICRHIC LHCLHC

Vogt, hep-ph/0205330

Quarkonia at LHC: (bb) d/dy @ LHC ~20 x RHIC melts only at LHC

’ TD ~ J/ TDWong, PRC 72 (2005) 034906Alberico, hep-ph/0507084

Small regenerationGrandchamp et al., hep-ph/0507314

’ can unravel J/ suppression vs. regeneration

Gunion and Vogt,

NPB 492 (1997) 301

’/ vs pt sensitive to system temp. & size

H.Satz


Quarkonia at LHC:experimental challenges

Important contribution to production from B J/(’) + X ~20% of J/~40% of ’

Normalization: Drell-Yan not available for normalization (from qq, while quarkonia

from gg at LHC; and small cross section at LHC)

W, Z?Different Q2, x

Open heavy flavour, but …Energy loss?Thermal charm production?

Possible alternative: RAA (à la PHENIX)

Need to measure this!


+- +- +-

e+e-

Quarkonia acceptances

-4<<-2.5

J/

-4<<-2.5

ac

ce

pta

nc

e (

%)

J/


ALICE +- ALICE e+e- CMS +- ATLAS +-

acc. -4 < < -2.5 || < 0.9 || < 2.5 || < 2

M res. 65 MeV 35 MeV 37 MeV 70 MeV

J/, ’150, 7 245, -- 313, -- 60, --

perf. , ?’ , ??’ , ?’ , ’

pt J/ 0-20 GeV 0-10 GeV few-20 GeV

Charmonia PerformanceBkg input: dNch/dy~2500-4000 in central Pb-Pb. for 1 month

central central central

BSS /

min. bias

BSS /


ALICE +- ALICE e+e- CMS +- ATLAS +-

acc. -4 < < -2.5 || < 0.9 || < 0.8(2.4) || < 2

M res. 90 MeV 90 MeV 54(85) MeV 145 MeV

,’,’’30, 12, 8 21, 8, -- 50, 17, 12 45, --, --

perf. , ’, ?’’ , ?’, no ’’ , ’, ’’ , ?’, no ’’

pt 0-8 GeV -- few-10 GeV

Bottonia Performance

||<2.4

||<0.8

central central min. bias central

BSS /

Bkg input: dNch/dy~2500-4000 in central Pb-Pb. for 1 monthBSS /


J/ from B in CMS & ALICE

primary J/

J/from B

energy LHCat 2.0~J/ψ all

B from J/ψ

J/ +- J/ e+e-

CMS: CMS/NOTE 2001/008, ALICE: CERN/LHCC 99-13


EXTRA SLIDES


Why RAA is flat Surface effectMost partons from inner part are totally absorbed

Energy loss is “saturated”: many partons radiate all their energy before getting outLong path lengths exploited only by high energy partons effectively, RAA doesn’t increase at high pT

Exercise: RAA increases with pT

Prod. points in (x,y) for partons giving hadrons with pT > 5 GeV:

increasing s

10.5 with , EE

LL

Loizides, PhD Thesis, nucl-ex/0501017


Further handle on L-dependence*

First RAA vs appearing …(see talk by d’Enterria)

= 0

= /2PHENIX 0 prel. vs PQM

Data show stronger dep. than PQM model

PQMPQM

STAR Coll., PRL 93 (2004) 252301

Note: model is not E L2, rather E L * Beware: effect of collective flow on RAA vs !?!


Open points (2): the opacity problem

Can we really probe the medium?

Need to relate extracted to an energy density QCD estimate for ideal QGP:

A recent analysis* of RHIC data, similar to that presented, extracts energy density 5 larger than that estimated from produced transverse energy dET/dy (Bjorken estimate)

Opacity problem: the interaction of the hard parton with the medium is much stronger than expected

q

)(2)(ˆ 4/3 q (Baier)

Baier, NPA 715 (2003) 209.* Eskola, Honkanen, Salgado, Wiedemann, NPA 747 (2005) 511.


LHC 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


Application: Parton Quenching Model

Dainese, Loizides, Paic, EPJC 38 (2005) 461.

QW + Glauber-based medium geometry and density profile + PYTHIA for parton generation and fragmentation

The procedure in short:1) generate parton (q or g) with PYTHIA (or back-to-back pair)

2) calculate its L and average along the path

3) use quenching weights to get energy loss

4) quench parton and then hadronize it (independent fragm.)

q

qL ˆ ,

),ˆ,;( LqCEP RPYTHIA

TR pC ,

Fragm

entat ion

pT

pT – pT

dN/dpT

)]()(ˆ[ sTTsq BA


Charm Energy Loss at RHICCompute RAA for c, D, e (from D)

Baseline: PYTHIA, with EKS98 shadowing, tuned to match pT-shape of D cross section measured in d-Au by STAR

c-quark E loss as for light-flv hadrons, but using (mc/Ec)-dependent QW

extracted from 0,h RAA (central)

Thermalize charms that lose all energy dN/dmT mT exp(-mT/T), T = 300 MeV

Use a range in to visualize limited sensitivity of RAA to itself

Armesto, Dainese, Salgado, Wiedemann, PRD 71 (2005) 054027.EKS: Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61.

q

qq

baseline dN/dpT

baseline RAA


D0 K-+: Selection of D0 candidates

increase S/Bby factor ~103!

central Pb-Pb events


Expected Sensitivity to RAA

D0 K B e + X

15% systematic from efficiency corrections 15%

12% theory uncertainty in energy extrapolation 8%

-- charm electron subtraction ~5%

8% normalization error (<Ncoll>) 8%


Quarkonia Acceptances

J/

||<0.9

||<0.9

2.5<<4.0

2.5<<4.0

J/

Di-electronchannel

Di-muonchannel


ATLAS: b-tagged Jets

Based only on impact parameter selection

Central Pb-Pb (HIJING) events

Rejection factor against light-quark jets vs b-tagging eff.

Factor 50 rejection when efficiency 40% required

Should improve when combined with tagging

b efficiency

u re

ject

ion

heavy quarks in view of the lhc

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