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SQM 2007 Levo č a, Slovakia, June 24-29, 2007. ALICE potential for heavy-flavour physics. Andrea Dainese INFN – Legnaro for the ALICE Collaboration. Contents. Charm and beauty at the LHC Physics motivation for open flavour and quarkonia measurements Heavy-flavour program in ALICE

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alice potential for heavy flavour physics

SQM 2007

Levoča, Slovakia, June 24-29, 2007

ALICE potential for heavy-flavour physics

Andrea Dainese

INFN – Legnaro

for the ALICE Collaboration

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

contents
Contents
  • Charm and beauty at the LHC
    • Physics motivation for open flavour and quarkonia measurements
  • Heavy-flavour program in ALICE
    • Measurements in preparation
    • Examples of expected performance (charm & quarkonia)
    • more on beauty  J.Faivre’s talk

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

lhc hard cross sections lots of heavy quarks

factor ~2

uncertainty

large

LHC: hard cross sectionslots of heavy quarks!
  • NLO predictions (ALICE baseline for charm & beauty)

MNR code (NLO): Mangano, Nason, Ridolfi, NPB373 (1992) 295.

beauty

charm

* M.Mangano

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

the charm of small x gluons

charm

beauty

Cartoon

The charm of small-x gluons
  • Probe unexplored small-x region with HQs at low pt and/or forward y

s=14 TeV

D mesons pt0, y=0

J/ypt0, y4

s=14 TeV

x~10-4

x~10-6

  • Charm measurements at low-pt or forward y

 Window on high-density PDFs phenomenology:

gluon saturation / recombination effects / CGC

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

heavy quarks as medium probes energy loss

Parton Energy Loss by

  • medium-induced gluon radiation
  • collisions with medium gluons

pred:

u,d,s: m~0, CR=4/3

(difficult to tag at LHC)

g: m=0, CR=3

> E loss, dominant at LHC

c: m~1.5 GeV, CR=4/3

small m, tagged by D’s

b: m~5 GeV, CR=4/3

large mass, < E loss

QCD medium

Heavy quarks as medium probes:Energy Loss

q: colour triplet

  • Parton Energy Loss by
  • medium-induced gluon radiation
  • collisions with medium gluons

g: colour octet

Q: colour triplet

Dokshitzer and Kharzeev, PLB 519 (2001) 199. Armesto, Salgado, Wiedemann, PRD 69 (2004) 114003.

Djordjevic, Gyulassy, Wicks, nucl-th/0512076

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

hq energy loss at lhc
HQ Energy loss at LHC

massive

heavy-to-light ratio

see also talk by W.Horowitz

Wicks, Gyulassy, “Last Call for LHC Predictions” workshop

Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

heavy quarks as medium probes azimuthal asymmetry v 2
Heavy quarks as medium probes:Azimuthal asymmetry (v2)
  • 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
  • at higher pt: path-length dependence of E loss in almond-shaped medium

E loss only

flow+reco

van Hees, Rapp, Greco, “Last Call for LHC Predictions” workshop

Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

quarkonia at lhc y cc bb

enhanced regeneration

enhanced suppression

30

SPS

RHIC

LHC

Quarkonia at LHC: y (cc) &  (bb)
  • J/ suppression & regeneration?
  • c, y’ suppression (J/ TD ~ 1.5-2 Tc)?

TLHC >> J/ TD

  •  melts only at LHC
  • ’ TD ~ J/ TD
  • Small  regeneration
  • ’ can unravel J/
  • suppression VS regeneration

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

the alice detector
The ALICE Detector

Size: 16 x 26 meters

Weight: 10,000 tons

|h| < 0.9, B = 0.5 T

TPC + silicon tracker

g,e, p, K, p identification

-4 < h < -2.5

muons

ALICE Collaboration: >1000 people, 30 countries, ~ 90 Institutes

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

getting ready for beam
Getting Ready for Beam!
  • Ready to move

MUON arm: largest dipole ever

TPC (largest ever) installed,

ITS moving in

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

open charm and beauty

D0 Kp

D+ Kpp

Ds KKp

D*  D0p

D0 Kpr

LcpKp

  • D0 Kp

D+ Kpp

Ds KKp

D*  D0p

D0 Kpr

LcpKp

  • D0 Kp

D+ Kpp

Ds KKp

D*  D0p

D0 Kpr

LcpKp

TOF (K/p id)

under

study

under

study

under

study

TPC (tracking)

ITS (vertexing)

TPC (tracking)

m

K p

MUON (tracking,id)

  • B  e+X

B5 pr.

BJ/yee

  • B  e+X

B5 pr.

BJ/yee

ITS (vertexing)

under

study

under

study

  • B m+X

ITS (vertexing)

TPC (tracking e/p id)

TRD (e/p id)

e

Open charm and beauty

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

vertexing track d 0 resolution

rf: 50 mm

rec. track

e

z: 425 mm

Primary

Vertex

PIXEL CELL

B

< 60 mm (rf)

for pT > 1 GeV/c

d0

X

Two layers:

r = 4 cm

r = 7 cm

Vertexing: track d0 resolution

Resolution mainly provided by the 2 layers of silicon pixels

 9.8 M

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

slide13

pair of opposite-charge tracks with large impact parameters

  • good pointing of reconstructed D momentum to the primary vertex
  • large distance (dPS) between primary and secondary vertex
  • good pointing of reconstructed D momentum to the primary vertex

D0

D+

Invariant mass analysis

50

40

30

D0

D+

20

10

1 year at nominal luminosity

(109 pp events, 107 central Pb-Pb events)

Charm reconstruction: D0 K-p+ & D+ K-p+p+

  • Two vertexing algos with full error-matrix treatment
  • Large combinatorial background (dNch/dy=6000 in Pb-Pb simul.)
  • Main selection: displaced-vertex selection

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

beauty in the barrel displaced e s displaced j y ee

J/y pseudoproper

decay time (pt>5GeV)

J/y e+e-

primary

secondary

Beauty in the barrel:displaced e’s, displaced J/yee
  • Excellent electron identification capabilities (TPC and TRD)
  • Displaced electrons (& di-electrons from J/y from B decays) tagged by an impact parameter cut (ITS)

see talk by J.Faivre

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

charm and beauty e loss r aa
Charm and Beauty E Loss : RAA

D0 Kp

D+ Kpp

B  e + X

mC = 1.2 GeV

mC = 0

B  e

E loss calc.:

Armesto, Dainese, Salgado, Wiedemann

mb = 4.8 GeV

1 year at nominal luminosity

(107 central Pb-Pb events, 109 pp events)

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

heavy to light ratios

probes colour-charge dep.

of QCD energy loss

probes mass dep.

of QCD energy loss

Heavy-to-light ratios

E loss calc.:

Armesto, Dainese, Salgado, Wiedemann

1 year at nominal luminosity

(107 central Pb-Pb events, 109 pp events)

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

charm v 2 d example
Charm v2: D+ example
  • First estimate of statistical errors on D+ v2:
    • best sensitivity at intermediate pt: 3 – 7 GeV/c  charm recombination
  • Under study: performance with D0 + D+

2107 min.bias evts 2107 6<b<9 fm evts

v2 calc. from Ko et al.

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

beauty via forward muons

RCP

ALICE muon spectrometer acc.:

-4 < h < -2.5, pt > 1 GeV, p > 4 GeV

Wm (medium-blind reference)

dominates for pt > 30 GeV/c!!

b quark

E loss

thin: no mass effect

thick: mass effect

Beauty via (forward) muons
  • Muons “identified” in the spectrometer (-4 << -2.5)

 single muons in the spectrometer:

b dominates for pt > 2-3 GeV/c

inner bars: stat. errors

outer bars: syst. errors

Pb-Pb 0-5%

(1 month)

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

quarkonia

ITS (vertexing)

TPC (tracking)

TRD (e/p id)

e

e

m

m

MUON (tracking,id)

Quarkonia

Measured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

quarkonia performance
Quarkonia Performance

Bkg input: dNch/dy=4000 in central Pb-Pb. for 1 month

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

medium effect on quarkonia quarkonia bb quarkonia r aa
Medium effect on Quarkonia:Quarkonia/BB , Quarkonia RAA
  • Normalization of quarkonia yields:
    • BB yield (from intermediate-mass di-leptons), but b E loss?
    • Possible alternative: RAA (à la PHENIX),

but different c.m.s. energy,

need p-Pb for initial-state effects

Plots for m+m- channel

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

summary
Summary
  • LHC: heavy quarks and quarkonia factory
  • Heavy quarks as probes of QCD in extreme conditions
    • 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
  • Charmonia & bottomonia as probes of QCD phase transition
  • ALICE in excellent position:
    • dedicated detectors (ITS, TRD, MUON)
    • promising performance for all key measurements

Thanks to:

F.Antinori, C.Blume, C.Bombonati, E.Bruna, G.E.Bruno, Z.Conesa, P.Crochet, H.Ding, J.Faivre, R.Guernane, M.Lunardon, G.Martinez, M.Masera, F.Prino, R.Turrisi

and ALICE “HF & Quarkonia” working group

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

extra slides
EXTRA SLIDES

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

lhc running conditions
LHC running conditions

pp nominal run

Pb-PB nominal run

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

Ldt = 5.1026 cm-2 s-1 x 106 s

5.1032 cm-2 PbPb run, 5.5 TeV

NPbPb collisions = 2 .109 collisions





Muon triggers:

~ 100% efficiency, < 1kHz

Muon triggers:

~ 100% efficiency, ~ 1kHz

Electron triggers:

~ 50% efficiency of TRD L1

20 physics events per event

Electron triggers:

Bandwidth limitation

NPbPb central = 2 .108 collisions

Hadron triggers:

Npp minb = 2 .109 collisions

Hadron triggers:

NPbPb central = 2 .107 collisions





SQM 2007 - Levoca, 28.06.07 Andrea Dainese

pp perspectives for the 1 st month

1 year at nominal luminosity

~1 month at end 2007

pp: perspectives for the 1st month
  • When? Latest statement from the machine (June 7): “Machine Closure: 31.8.07 Set up of machine, injection, followed by up to 10 weeks of pp collisions: Sept. to Dec. 2007”
  • Expected statistical errors for a low-stats sample:
    • Scaling of statistical errors according to Nevts
    • No dedicated cuts study yet

D0 Kp

B  e + X

Detector configuration:

ITS + TPC + TOF

Detector configuration:

ITS + TPC + TRD

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

quarkonia mass spectra

di-muon -4<h<-2.5

J/y family

 family

di-electron |h|<0.9

Mμμ(GeV/c)

Mμμ(GeV/c)

Quarkonia: mass spectra

Measured both in the di-electron (midrapidity, TRD) and di-muon (forward rapidity, MUON) channel

1 month at nominal luminosity

(107 central Pb-Pb events)

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

suppression scenarii
Suppression Scenarii
  • Suppression-1
    • Tc =270 MeV
    • TD/Tc=1.7 for J/Y
    • TD/Tc= 4.0 for .
  • Suppression-2
    • Tc=190 MeV
    • TD/Tc=1.21 for J/Y
    • TD/Tc= 2.9 for .

Ph. CROCHET, F, GUERIN, R. GUERNANE, S. GRIGORYAN et al.

PRC72 034906(2005)

Hep-ph/0507084(2005)

Good sensitivity

J/Y, (1S) & (2S)

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

energy loss from rhic to lhc i

massive

heavy-to-light ratio

Energy loss, from RHIC to LHC (I)

Radiative energy loss (BDMPS): charm ~ m=0 quark  probe colour charge dependence; beauty  probe mass dependence

Pb-Pb 5.5 TeV

Au-Au 200 GeV

Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

energy loss from rhic to lhc ii
Energy loss, from RHIC to LHC (II)

Heavy quarks (esp. beauty) may help to disentangle relative importance of radiative and collisions losses

see also talk by W.Horowitz

Wicks, Gyulassy, “Last Call for LHC Predictions” workshop

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

energy loss from rhic to lhc iii
Energy loss, from RHIC to LHC (III)

Conceptually different approach:

Fragmentation & dissociation of heavy-flv hadrons inside QGP

D

B

D+B

I.Vitev, A.Adil, “Last Call for LHC Predictions” workshop

SQM 2007 - Levoca, 28.06.07 Andrea Dainese

heavy quarks as medium probes azimuthal asymmetry v 21

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

RHIC LHC

Armesto, Cacciari, Dainese, Salgado, Wiedemann, “Last Call for LHC Predictions” workshop

Heavy quarks as medium probes:Azimuthal asymmetry (v2)
  • 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

van Hees, Rapp, Greco, “Last Call for LHC Predictions” workshop

SQM 2007 - Levoca, 28.06.07 Andrea Dainese