Status of PPR Chapter 6.5 Charm and Beauty
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Transcript of 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
ALICE Physics Forum - Utrecht, June 14, 2005 Andrea Dainese 2
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
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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
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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
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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
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Rel. statistical error for 33-58%
33-58%
0-5%
Larger bins than for 0-5% have to be used
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pT distribution for 33-58%
same systematic errors (band)as for 0-5% assumed
(0-5%)
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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
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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?
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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
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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
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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
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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
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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
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
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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
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.)
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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
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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
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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.
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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
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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
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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
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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
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The Physics plots (1)D0 cross section measurement
mc
scalesPDFs
down to pt ~ 0 !
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The Physics plots (2)Charm quenching: sensitivity to D-meson suppression
updated predictionsArmesto, Dainese, Salgado, Wiedemann, PRD71 (2005) 054027
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Study shadowing in p-Pb at 8.8 TeV?
R.Grosso, PhD thesis (2004)
(to be included)
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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)
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6.5.7 Beauty with muons in Pb-Pb
(Guernane et al.)
(still to be included,but ~ copy-paste from ALICE note)
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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)
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EXTRAS
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Results for 33-58%
Not divided by bin width
Larger bins than for 0-5% have to be used
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S/B and Significance for 33-58%
33-58%
0-5%
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6.5.2 Available measurements
CDF D-meson data at 1.96 TeV
FONLL predictions by Cacciari and Nason
hep-ex/0307080
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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
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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