Status of PPR Chapter 6.5 Charm and Beauty

ALICE Physics Forum - Utrecht, June 14, 2005 Andrea Dainese 1

Status of PPR Chapter 6.5

Charm and Beauty

Editors: F. Antinori2 and A. Dainese1,2

1University and 2INFN – Padova


Before moving to ~editorial matters… …The Latest News:

“The charm of non-central collisions”

This item is missing in 6.5, although important (need to know requested number of events for RCP & v2 studies… see physics motivations later on)

First steps:

Calculated heavy-quark yields as a function of centrality (using centrality classes as defined in PPR 6.1)

Estimated D0K performance in semi-periph. collisions (preliminary)

Goal: have something on D0 in the PPR, maybe something on B e+X


Heavy quarks and dNch/dy vs centrality(PPR 6.1 classes)

class 1 2 3 4 5

b (fm) 0-3 3-6 6-9 9-12 >12

%Pb-Pb 0-3.6% 3.6-14.6% 14.6-32.6% 32.6-58% 58-100%

Nevents(107 min.bias)

3.6x105 1.1x106 1.8x106 2.5x106 4.2x106

<b> (fm) 1.9 4.7 7.6 10.6 14.3

<Npart> 385 297 177 70 8

<Ncoll> 1644 1140 570 156 12

<dNch/dy> HIJING

6200 3800 1800 600 100

Ncc/ev 118 82 42 12.5 1.2

Nbb/ev 4.8 3.4 1.7 0.5 0.04b-dependence of shadowing from Emel’yanov, Khodinov, Klein, Vogt, PRC61 (2000) 044904


Heavy quarks and dNch/dy vs centrality (2)

b (fm) 0-3.7 7.2-10.1 10.1-12.3 7.2-12.3 12.3-14.2

%Pb-Pb 0-5% 20-40% 40-60% 20-60% 60-80%

Nevents(107 min.bias)

5x105 2x106 2x106 4x106 2x106

<b> (fm) 2.4 8.4 11 9 13

<Npart> 372 143 56 121 16

<Ncoll> 1616 419 108 324 20

<dNch/dy> HIJING

~6000 ~1200 ~400 ~950 ~100

Ncc/ev 115 31 9 24 1.8

Nbb/ev 4.6 1.3 0.3 1.0 0.06b-dependence of shadowing from Emel’yanov, Khodinov, Klein, Vogt, PRC61 (2000) 044904

for RCP for v2


D0 K in 33-58% Pb-Pb (2.5x106 evts)

Used signal and background samples for Pb-Pb 0-5%

Rescaled signal by 0.11 (decrease of Ncc/event)assumed same shadowing as in central collisions…

Rescaled backgr. by [(dNch/dy)33-58%/(dNch/dy)0-5%]2 ~ 0.01

Assumed same tracking & PID efficiencies & resolutions as in central collisions

Issue: primary vertex reconstruction may be worsexy: same resolution as in central, given by beam size

z: worse resolution z(dNch/dy=600) = 15 m (from Catania’s vertex reconstruction results) [z(dNch/dy=6000) = 5 m]

not a problem: z used only for pointing angle, where resolution dominated by secondary vertex z-res. ~ 80 m

(roughly) Retuned cuts for new normalization


Rel. statistical error for 33-58%

33-58%

0-5%

Larger bins than for 0-5% have to be used


pT distribution for 33-58%

same systematic errors (band)as for 0-5% assumed

(0-5%)


RCP for 0-5%/33-58%

• only stat. errors (dominated by 33-58% errors, if RCP=1) • errors estimation for more likely RCP~0.4 in progress

• systematic error should mainly come from <Ncoll>

dydpNd

dydpNd

N

NpR

tP

tC

Ccoll

PcolltCP /

/)(

2

2


First look at v2 (quick&dirty)

))(2cos( ))](2cos(21[ 220 RPRP vvNd

dN

For pT < 5 GeV/c, candidate are signal + background

need to study bkg v2 (e.g. using sidebands or ev. mixing) and subtract it requires dedicated study

For pT > 5 GeV/c, background is negligible

just get v2 from all D0 candidates (only signal)

First trial, for pT > 5 GeV/c: assumed v2 ~ 0.10-0.20

0.201210-14

0.061205-14

0.12347-10

0.08745-7

v2 (statistical)SignalpT bin (GeV/c)

33-58%2.5x106 evts

0.123x1210-14

0.043x1205-14

0.073x347-10

0.053x745-7

v2 (statistical)SignalpT bin (GeV/c)

20-60% 4x106 evts

Need more “non-central” events?


Back to editorial matters…Contents of chapter 6.5

6.5.1 Physics motivations

6.5.2 Available measurements of heavy-flavour

hadroproduction

6.5.3 Charm and beauty production at LHC

6.5.4 Exclusive charm reconstruction with D0 K6.5.5 Perspectives for the study of charm quenching

6.5.6 Beauty detection in the semi-electronic decay

channels


New sections to be added

6.5.7 Beauty in the muon channelsSingle and di- muons in Pb-Pb (by R. Guernane)

Presented as work in progress: 3- and 4-muons in pp and pA (prel. study by A. Morsch) e- correlations (prel. study by P. Crochet)

6.5.8 pp-specific section: detection possibilities for nonlinear effects in gluon evolution via charm


6.5.1 Physics MotivationsHeavy quarks: produced in early stage, hard scale, calculable in pQCD

Added pp and pA specific motivations:test pQCD and factorization in pp/pA

look for break down of factorization: shadowing, gluon saturation, Color Glass Condensate

look for multiparton scattering in pA

Revised AA motivations. Heavy quarks can probe:density of medium, via energy loss and its dependences (mass, colour charge)

degree of thermalization, via v2


6.5.1 Physics MotivationsProbing high-density initial state with heavy quarks

nonlinear gluon evolutions in pp

shadowing in pA (AA)

CGC in pA (AA)

Multiple parton scattering in pA





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





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 is can be estimated from measured single inclusive b cross section

predicted rate: cccc/cc ~ 10% (Treleani et al.)


6.5.1 Physics MotivationsMedium effects in AA:

heavy-quark energy loss

azimuthal asymmetry / v2 / coalescence

)()()( )(/)( t

hAAt

BDAAthBD pRpRpR

RD/h enhancement probes color-charge dep. of E lossRB/h enhancement probes mass dep. of E loss

Armesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027.

gq EE mass effect


6.5.1 Physics MotivationsMedium effects in AA:

heavy-quark energy loss

azimuthal asymmetry / v2 / coalescence

Greco, Ko, Rapp, nucl-th/0312100

RHIC 200 GeVThe azimuthal asymmetry (v2) of D and Bmesons in non-central collisions tests:

• at low/moderate pT: coalescence scenario, v2 of c/b quarks, hence degree of thermalization of medium

• at higher pT: path-length dependence of E loss (almond-shaped medium => v2~5-10%)

= 0

= /2


6.5.2 Available measurements

Not only pA and AA, included also ppbar (Tevatron)

pA:Charm production in pA fixed target up to sqrt{s} ~ 40 GeV: understood and well described by binary scaling

AA:The NA50 di-muons enhancement puzzle

Single electrons from PHENIX (RAA and v2)

Additions: Charm and beauty in ppbar at 1.96 TeV (compared to FONLL calc.)Charm in d-Au at 200 GeV: STAR D meaurement compared to FONLL calc.


6.5.3 Production at LHCTotal cross sections at NLO in nucleon-nucleon collisions from MNR code with CTEQ5M and MRST2001

Extrapolation to p-Pb and Pb-Pb collisions

Spectral shapes and tuning of event generators (PYTHIA)

Hadronization and decays

Being added:

figures with theoretical uncertainty bands from MNR and, optionally, FONLL

theoretical uncertainty for extrapolation of pp measurement from 14 TeV to 5.5 TeV


6.5.3 Production at LHC

0.5 mt < F,R < 2 mt, 1.3 < mc < 1.7 GeV, 4.5 < mb < 5.0 GeV


6.5.3 Production at LHC

0.5 mt < F,R < 2 mt, 1.3 < mc < 1.7 GeV, 4.5 < mb < 5.0 GeV

Extrapolation of the pp data from 14 to 5.5 TeV

+10/-15% syst. error

charm 14/5.5 beauty 14/5.5

+5/-10% syst. error


6.5.4 D0 KD0 K- analysis in central Pb-Pb (0-5%)

done for B = 0.4 T and dNch/dy = 6000extrapolation to lower multiplicity (3000) extrapolation to lower field (0.2 T)

Same analysis in pp: focus on pp-specific problems, namely primary vertex uncertainty due to necessity to reduce luminosity at ALICE I.P. to ~1030 cm-2s-1

Being included: p-Pb study by R. Grosso Physics performance:

uncertainties in charm cross section measurement

energy loss studies: sensitivity to RAA and ratio D/hadrons


The Physics plots (1)D0 cross section measurement

mc

scalesPDFs

down to pt ~ 0 !


The Physics plots (2)Charm quenching: sensitivity to D-meson suppression

updated predictionsArmesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027


Study shadowing in p-Pb at 8.8 TeV?

R.Grosso, PhD thesis (2004)

(to be included)


6.5.6 B e+X in Pb-Pb

inner bars: stat. errorsouter bars: stat. pt-dep. syst. errorsnot shown: 11% normalization error

Note: quenching curves mainly for illustration.Pb-Pb vs. pp comparison needed to study E lossStudy of Be+X in pp is in progress in Padova

Using electrons in2 < pt < 20 GeV/c

obtain B meson2 < pt

min < 30 GeV/c

(complete study presented at ALICE Week in March)


6.5.7 Beauty with muons in Pb-Pb

(Guernane et al.)

(still to be included,but ~ copy-paste from ALICE note)


Summary

Ch 6.5 text in good shape: ~70 pages!Received comments by Jurgen, Yiota, Luciano (thanks!)

We plan to still include:D0 in p-Pb results

D0 performance in semi-peripheral Pb-Pb

D quenching studies

B possible non-linear effects in pp

a paragraph on future developments (other channels / physics observables)


EXTRAS


Results for 33-58%

Not divided by bin width

Larger bins than for 0-5% have to be used


S/B and Significance for 33-58%

33-58%

0-5%


6.5.2 Available measurements

CDF D-meson data at 1.96 TeV

FONLL predictions by Cacciari and Nason

hep-ex/0307080


6.5.2 Available measurementsCDF B J/ + X data at 1.96 TeV

FONLL and MC@NLO predictions by Cacciari, Frixione, Mangano, Nason and Ridolfi, hep-ph/0312132


6.5.2 Available measurementsSTAR D-meson data in d-Au at 200 GeV

nucl-ex/0407006nucl-ex/0404029 (high pt prelim.)

FONLL, hep-ph/0502203

Documents

Status of PPR Chapter 6.5 Charm and Beauty