Heavy flavours & quarkonia @ LHC

[email protected] [email protected] Sibiu, 20/08/08

• motivationsmotivations

• selected physics channelsselected physics channels

quarkonia, quarkonia, B-hadron x-section, B-hadron x-section, « hadronic » charm, « hadronic » charm,

heavy flavour quenchingheavy flavour [email protected]


Heavy-flavour x-sections @ LHC

c(LHC) = c(RHIC) × 10

b(LHC) = b(RHIC) × 100

W(LHC) = (RHIC) × 10

Z(LHC) = (RHIC)

K. Safarik


Dileptons @ LHC

world data on total x-section of e+e- hadrons (PDG06)

a similar plot is accessible in Pb-Pb @ LHC within a few weeks

(p

b)

s (GeV)

J/ (1S) Z0

350·103 700·103 300·103 500·103 25·103 11·103

typical number of reconstructed resonances in min-bias PbPb @ 5.5 TeV (1 month)


Single leptons @ LHC

simulation by Z. Conesa del Valle

pp @ 14 TeV

charm bottom W±

charm bottom W±

4·108 4·105 11·103

expected number of measured muons in min-bias PbPb @ 5.5 TeV (1 month)


A closer look at heavy-quark cross-section

hep-ph/0601164, J. Phys. G 32 (2006) 1295, J. Phys. G 35 (2008) 054001

• NLO predictions for pp @ LHC: a factor ~ 2 uncertainty

• (14 TeV) / (5.5 TeV) ~ 10%

measuring (c,b) in pp @ 14TeV is top priority

charm thermal production ~ 25%

(assumes large medium temperature)

PbPb @ 5.5 TeV

charm

pp @ 14 TeV

bottom

(14 TeV) / (5.5 TeV)


Quarkonia suppression @ LHC

• whether J/ melts or not @ RHIC it will be strongly either suppressed or regenerated @ LHC

• use (2S) to unravel J/ sup. vs. reco. reco. is small: L. Grandchamp et al., PRC 73 (2006) 064906

• (1S) melts significantly only at LHC

• additional suppression by hard gluons

• relevance of quarkonium ratios vs. pt R.

Vogt in J. Phys. G 35 (2008) 054001

quarkonium dissociation temperatures

A. Mocsy & P. Petreczky, Phys. Rev. Lett. 99 (2007) 211602

PbPb @ 5.5 TeV

RHICLHC

hard gluon induced quarkonium breakup hep-ph/0311048


Charmonium regeneration @ LHC

1. peculiar centrality dependence

2. predictions strongly depend on cc

3. (re-)dissociation by comovers

4. regeneration smaller <p2t>

note: N(B J/) / N(direct J/) ~ 20% in 4

A. Andronic et al., Phys. Lett. B 652 (2007) 259, J. Phys. G 35 (2008) 054001, A. Capella et al., arXiv:0712.4331 [hep-ph], R. Thews et al., J. Phys. G 35 (2008) 054001

1. 2. 3.

4.


Heavy quark quenching @ LHC: new ratios available

N. Armesto et al., Phys. Rev. D 71 (2005) 054027, J. Phys. G 35 (2008) 054001

BAA

DAA

hAAbcqg RRREEE

hAA

BDAA

hBD RRR )(/)( DAA

BAA

DBAA RRR /

• isolate mass dep. of E

• sensitivity disappears at large pt

• lower sensitivity to qhat

• RD/h probes color charge dep. of E

• RB/h probes mass dep. of E


Heavy quark quenching @ LHC: new reference available

Z. Conesa del Valle et al., Phys. Lett. B 663 (2008) 202, J. Phys. G 35 (2008) 054001

• heavy quark energy loss:

• shifts down the (c,b)/W crossing point by ~ 5-7 GeV/c

• suppresses muon yield by a factor 2-5 for 2 < pt < 20 GeV/c

• W affected by shadowing only


Heavy flavour flow @ LHC

more details in “Heavy Ion Collisions at the LHC, Last Call for Predictions”, May-June 2007, CERN

proceedings: J. Phys. G 35 (2008) 054001

• resonance interactions increase v2

• v2 quantitatively similar at RHIC & LHC

H. van Hess et al., Phys. Rev. C 73 (2006) 034913, J. Phys. G 35 (2008) 054001


Heavy ions @ LHC

ALICE

CMS

ATLAS


Heavy flavours with ALICE

electron-muon coincidences: open charm & bottom

ITS, TPC, TRD, ToF (||<0.9)

(di-)electrons: J/, ’, , ’,’’, open charm, open bottom, W±,Z0

muon spectrometer (-2.5<<-4)

(di-)muons: J/, ’, , ’,’’, open charm, open bottom, W±, Z0

ITS, TPC, TRD, ToF (||<0.9)

hadrons: D0, D±,…


Heavy flavours with CMS & ATLAS

muon spectrometer & silicon tracker in central barrel & end-caps (||<2.5)

studies limited to J/, ’, , ’,’’ reconstruction & b-jet tagging

J/, ’, , ’,’’, open bottom, Z0


Acceptance for heavy flavour measurements

• complementarity between the 3 experiments

• ATLAS & CMS acceptance is large in & limited to high pt

• ALICE combines hadrons, electrons, muons & covers low pt & high • ATLAS, CMS & ALICE-electrons/hadrons have inner tracking

• ATLAS & CMS electron/hadron channels not yet investigated


Selected physics channels

• Quarkonia

• B from secondary J/

• B from dileptons

• B from single leptons

• D0 K

• Heavy flavour quenching

only “published” results


Quarkonia


Expected performances for quarkonia

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

acceptance -4<<-2.5 ||<0.9 ||<2.4 ||<2.5

charmonia

(J/) (MeV) 74 30 35 (w/o bkg) 68

S (×103) 677 120 146 8-216 (pt)

S/S+B 413 245 234 52-164 (pt)

bottomonia

() (MeV) 109 90 68-90 (bkg level) 145 (||<2)

S , ’, ’’ 6800,1800,100 900,350,- 20300,5900,3500 10000-15000

S/S+B , ’, ’’ 67,30,21 21,8 36,-,- 45-46

From A. Dainese @ HP2006, updated according to ALICE: J. Phys. G 32 (2006) 1295, W. Sommer et al. @ QM2006, CMS: J. Phys. G 34 (2007) 2307, CMS/note-2006/089, ATLAS: L. Rosselet @ HEP2007

• J/, : first detailed studies within one month

• ’: difficult (small S/B), ’, ’’: need 2-3 runs

WARNING: different simulation frameworks & different assumptions

bkg assumes dN/d = 2500-5000, S & S/S+B: one month min-bias PbPb (CC for ALICE e+e-)


Normalization for suppression studies

normalisation pros. cons.

open heavy flavours

most naturalquenching, thermal (charm) production

excited states sensitivity to medium size & temperature

hard partons, exp. reach (e.g. ’)

Z0, W± statistics, no hot medium effects

prod. mechanisms (gg vs. qqbar), Q2

RAA, Rcp “easy”mix cold & hot nuclear effects (i.e. need pA)

there is no golden normalization


Observables with bottomonia

ALICE: J. Phys. G 32 (2006) 1295, CMS: J. Phys. G 34 (2007) 2307

suppression 1: TC = 270 MeV, TD/TC = 4.0 (1.4) for ϒ(ϒ’)

suppression 2: TC = 190 MeV, TD/TC = 2.9 (1.1) for ϒ(ϒ’)

• statistics: one month PbPb @ 5.5 TeV

• large sensitivity to dissociation temperatures and medium size


More with quarkonia

R. Analdi, E. Scomparin, D. Stocco

polarization dN/dy in pp

• pp: test production mechanisms

• AA: probe QGP formation• probe gluon distribution at low x

• pp @ 14 TeV: J/ & pol. vs. pt

• PbPb @ 5.5TeV: J/ pol. vs. centrality, pol. needs 2-3 runs

(gen - rec) vs. pt

pp @ 14 TeV


Open charm & bottom: accessible channels

charm: exclusive hadronic

channels

• D0 K (tested in pp & PbPb)

• D+ K (tested in pp & PbPb)

• D±s KK (under study)

• D* D0 (under study)

• D0 K (under study)

• c pK (under study)

charm & bottom: semi-inclusive leptonic

channels

• c l + X (à la CDF & D0)

• b l + X (à la CDF & D0)

• b J/ + X (à la CDF & D0)

• b J/ + l (under study)

• bbbar 3 (should work in pp)

• bbbar l+l-,l-l+ (Bchain & BBdiff)

• bbbar l-l-,l+l+ (Bchain & B osc.)

more exotic (and more challenging): QQbar e, b > 5 prongs, b

J/ + X, etc


Selected physics channels

• Quarkonia

• B from secondary J/

• B from dileptons

• B from single leptons

• D0 K

• Heavy flavour quenching

only “published” results


Secondary J/ from B hadron decay

ALICE: CERN/LHC 2005-030, CERN/LHCC 99-13, ATLAS: EPJC 33 (2004) s1023, CMS: CMS NOTE 2006/031, 2001/008

(d0) < 50 µm for pt > 1.5/2/3 GeV/c in ALICE/CMS/ATLAS

• disentangle primary & secondary J/

• measure inclusive b cross-section

• probe b quark in-medium energy loss

N(B J/) / N(direct J/) ~ 20% in 4 @ LHC


secondary J/ from B decay in CMS, pt

> 5 GeV/c

Using secondary J/ from B decay to probe b quark energy loss

energy loss is included in 2 scenarios:

• collisional energy loss

• collisional + radiative energy loss

with energy loss:

• yield reduced by a factor ~ 4

• distribution gets significantly narrower

I.P. Lokhtin & A.M. Snigirev, Eur. Phys. J. C 21(2001)155


B signal from high-mass dimuons with vertexing

J. Phys. G 34 (2007) 2307

from BBbar

from Drell-Yan

min-bias PbPb one

month

r > 50 m suppresses Drell-Yan rate by 2 orders of magnitude with ~ 30% loss of signal


B signal from dimuons w/o vertexing

R. Guernane et al., ALICE-INT-2005-018, J. Phys. G 32 (2006) 1295

Mass (GeV/c2) 0-5 5-20

N from bb 41461793 6983130

unlike-sign totalunlike-sign from bottomunlike-sign from charm like-sign from bottom

• unfold mass continuum

• large statistics is expected

• systematics to be estimated

central PbPb (5%), one month


B hadron cross-section from single leptons

J. Phys. G 32 (2006) 1295, DIMUONnet

pp @ 14 TeV B +X

First step: extract Nl B

w/o 2nd vertex: unfold lepton dN/dpt via combined fit

large statistics constrains fit

107 PbPb (5%) evts (1 month)

pt > 2 GeV/c, 200 < d0 < 600 m

80000 e from B, S/(S+B) = 80%

2.1·1012 pp evts (1 year)

pt > 2 GeV/c

1.7·108 from B

with 2nd vertex: cut on dca & subtract remaining background

large purity of lepton sample

PbPb @ 5.5 TeV B

e+X


MC

minttmin

tt )(

)(1

dt)(

lB

BBBlBB pp

L

Npp

total number of lB

integrated luminosity

lepton global detection efficiency

Second step: correct for efficiency, acceptance & decay kinematics





• method widely used (UA1, CDF, D0)

• large pt reach, (very) small statistical errors, systematics ~ 10-15%

• allows to get B RAA(pt), should work for charm as well

• similar performances to be expected in ATLAS & CMS


Third step: the B-hadron inclusive differential cross-section

B semi-muonic decays

pp, s = 14 TeV

w/o 2nd vertex with 2nd vertex


107 central PbPb (5%)

• S ~ 13000• S/B ~ 10 %• S/(S+B) ~ 40

D0 K (3.8%) c = 123 m

J. Phys. G 32 (2006) 1295

background assumes dN/d = 6000 @ = 0

cos(pointing) > 0.98 d0K

d0 < - 40 000 m2

increase S/B by 103

Hadronic charm


system pp pPb PbPb

s (TeV) 14 8.8 5.5

trig MB MB CC

Nevt 109 108 107

time (months) 8 1 1

pt min (GeV/c) 0.5 0.5 1

Estat (%) 3 2 7

Esyst (%) 14 16 17

the most precise measurement of the total charm x-section in

pp collisions @ LHC

J. Phys. G 32 (2006) 1295

Hadronic charm differential x-section


mc, F/0, R/0, PDF

expected experimental errors are much smaller than theoretical uncertainties

bars: quadratic sum of statistical & systematic errors

J. Phys. G 32 (2006) 1295

Testing QCD with hadronic charm in pp collisions @ 14 TeV


tDpp

tDAA

coll

DAA dpdN

dpdN

NR

/

/1

tepp

teAA

coll

eAA dpdN

dpdN

NR

/

/1

J. Phys. G 32 (2006) 1295

1 nominal year: 107 central Pb-Pb events, 109 pp events statistics: bars, systematics: bands

sensitivity to shadowing for pt <~ 7 GeV/c & to energy loss for pt >~ 7GeV/c

Heavy quark quenching: traditional ratios


D from eB from e/ AAAADB RRR

hAA

DAAhD RRR //

J. Phys. G 32 (2006) 1295

sensitivity to color charge dependence

sensitivity to mass dependence

1 nominal year: 107 central Pb-Pb events, 109 pp events statistics: bars, systematics: bands

Heavy quark quenching: more ratios


Heavy flavours at the LHC provide a rich physics program

[email protected]

more analyses (not discussed here) are under study: heavy flavour flow, charm baryons, e- coincidences,

b-tagged jets, Z0, W±,…

first collisions in one month!

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Heavy flavours & quarkonia @ LHC

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