1. Spares
Giuseppe E. Bruno

2. low-x (a field of its own!)
large cross-sections
low-x (a field of its own!)
 accessible x1, x2 regions in the ALICE experiment
muon
arm
muon
arm
central
detector
central
detector
Giuseppe E. Bruno

3. Collisions… Proton + detector collision 11.09. run 58338 ev 27
Giuseppe E. Bruno

4. Perspectives for D± elliptic flow
GOAL: Evaluate the statistical error bars for measurements of v2 for D± mesons reconstructed from their Kpp decay in Pb-Pb collisions
v2 vs. centrality (b=collision impact parameter)
v2 vs. pT in different centrality bins
HOW: fast simulation to generate:
ND+ (DpT,Db) with an angular distribution
dND/dj = v2D,in cos [2(j-YRP)]
For each D+: an event made of Ntracks is superimposed
dN/dj = v2ev,in cos [2(j-YRP)]
Inputs of the simulation: ND+ (DpT,Db) , v2D,in, Ntracks ,v2ev,in
Outputs: v2D measured.
Giuseppe E. Bruno

5. v2 vs. pT How to increase the statistics? Sum D0→Kp and D±→Kpp
Semi-peripheral trigger
Sum D0→Kp and D±→Kpp
Sufficient for v2 vs. centrality
v2 vs. pT that would be obtained from 2·107 semi-peripheral events (e.g. 6<b<9 fm)
How to increase the statistics?
Large stat. errors on v2 of D± → Kpp in 2·107 MB events
6<b<9 fm
MB trigger
Giuseppe E. Bruno

6. Experience at colliders: CDF √sNN=1960 GeV
Since the B hadrons with as little as zero momenta produce J/y with momenta as large as 2 GeV/c, the measured cross section for pt(J/y)>1.25 GeV/c is sensitive to the complete pt(B) spectrum
Ref: D. Acosta et al Phys. Rev. D 71, (2005)
Giuseppe E. Bruno

7. Performance plot w.r.t. CDF
tot
tot J/y
J/y from B
bkg
ALICE
CDF
2<pT<3 Gev
pT>5 Gev
3<pT<5 Gev
pT>0
1 mb event
Giuseppe E. Bruno 7

8. Statistical Significance
Partial TRD installed (4 out of 18 super mod.)
Full TRD
All pairs
One track in
Both in
tot
J/y
bkg
S=34±6
S=14±3
S=15±5
S=5±2
Giuseppe E. Bruno

9. Beauty in the barrel: displaced J/ye-e+ tot J/y bkg
pT>5 Gev
102 10 1
Entries/100mm
-2000
-1000
1000
2000
3000
x [mm]
tot J/y
J/y from B
bkg
sum
prompt J/y x
2<pT<3 Gev
102 10 1
Entries/100mm
-2000
-1000
1000
2000
3000
x [mm]
tot J/y
J/y from B
bkg
sum
prompt J/y x
109 pp events
Analysis based on a simultaneous fit of
the invariant mass spectrum
an “impact parameter” to separate prompt from detached J/y, e.g. pseudo- proper decay time (CDF)
D.Acosta et al Phys. Rev. D 71 (2005)
This measurements can allow a determination of the dsbb/dpt cross-section down to pt≈0
Events/10 MeV
109 pp events
350
300
250
200
150
100 50
2.8
2.9
3.0
3.1
3.2
m(e+,e-) [GeV]
tot
J/y
bkg
Giuseppe E. Bruno

10. ALICE performance: Vertexing
3D reconstruction from tracks of primary (interaction) and secondary (decay) vertices position with full error-matrix treatment
Resolution on vertex position important for
Impact parameter resolution (in pp low multiplicity events)
Separation of secondary vertices from the primary
Determination of the pointing angle
Primary vertex in pp
Decay vertex D+  K-p+p+
Giuseppe E. Bruno

11. Physics at LHC - Philippe Pillot
Quarkonia in dimuon
pp, √s=14 TeV
1 month central Pb-Pb (0 < b < 3 fm)
Luminosity of 51026 cm-2s-1
Shadowing + PTμ > 1 GeV/c
Statistics in the interval M ± 2 σ
State
S[103]
B[103]
S/B
S/(S+B)1/2
J/Y
130
680
0.20
150 Y’
3.7
300
0.01
6.7
(1S)
1.3
0.8
1.7 29
(2S)
0.35
0.54
0.65 12
(3S)
0.42
0.48
8.1
J/Ψ mass resolution ~ 70 MeV/c2
Υ mass resolution ~ 100 MeV/c2
No clear signal for Ψ’ and Υ(3S)
(J. Phys. G 32 (2006) 1295)
03/10/08
Physics at LHC - Philippe Pillot
Giuseppe E. Bruno 11

12. PbPb cent, 0 fm<b<3 fm
Quarkonia to dimuons
1 month Pb-Pb
PbPb cent, 0 fm<b<3 fm
State
S[103]
B[103]
S/B
S/(S+B)1/2
J/Y
130
680
0.20
150 Y’
3.7
300
0.01
6.7
(1S)
1.3
0.8
1.7 29
(2S)
0.35
0.54
0.65 12
(3S)
0.42
0.48
8.1
Expected yields
J/y high statistics: 0-20 GeV/c
y’ poor significance
(1S) & (2S) : GeV/c
(3S) ok, but 2-3 runs needed
Giuseppe E. Bruno

13. Physics at LHC - Philippe Pillot
Quarkonia to dielectrons
1 month central Pb-Pb (10%)
Luminosity of 51026 cm-2s-1
Shadowing + pTe > 1 GeV
Statistics in the interval M ± 1.5 σ
State
S[103]
B[103]
S/B
S/(S+B)1/2
J/Ψ
120
100
1.2
245
(1S)
0.9
0.8
1.1 21
(2S)
0.25
0.7
0.35 8
J/Ψ mass resolution ~ 30 MeV/c2
Υ mass resolution ~ 90 MeV/c2
Ψ’ and Υ(3S) quite difficult
03/10/08
Physics at LHC - Philippe Pillot
Giuseppe E. Bruno 13

14. HF to single muon in p-p Signal:  from b/c decays Background:
 from /K decays
Can be extracted from data
 from the absorber
Subtraction: tracks do not point to the vertex, no FMD hits
Good preliminary results: high statistics needed
Slices in pT. Correct for diamond shape
Giuseppe E. Bruno

15. B signal from dimuons w/o vertexing
unlike-sign total
unlike-sign from bottom
unlike-sign from charm
like-sign from bottom
unfold mass continuum
large statistics is expected
systematics to be estimated
central PbPb (5%), one month
Mass (GeV/c2)
0-5
5-20
N from bb
41461793
6983130
(J. Phys. G 32 (2006) 1295 | Ph. ALICE workshop Sibiu 2008)
03/10/08
03/10/08
Physics at LHC - Philippe Pillot
Physics at LHC - Philippe Pillot 15

16. HF to muons BDsame B µ+ + D + X µ- + X BBdiff B µ- + X X + µ+
Single muons from beauty are dominant at high pT  fit on distribution tail
Muons from charms are dominant at low pT  difficult measurement due to large background
Muon pairs from B:
BDsame B
µ+ + D + X
µ- + X
BBdiff
BDsame
BBdiff B
µ- + X
X + µ+
Giuseppe E. Bruno

17. Physics at LHC - Philippe Pillot
Quarkonia acceptance
Dielectron channel
Dimuon channel
J/
J/
Dielectron trigger: pTe > 3 GeV/c  
Dimuon trigger: pTμ > 1 (2) GeV/c for J/ ()
03/10/08
Physics at LHC - Philippe Pillot
Giuseppe E. Bruno 17

18. Large suppression at RHIC!
n.p. electrons ~ as suppressed as expected for c only (no b)
yet, region above 3-4 GeV expected to be dominated by beauty...
non phot. el.
scaled to
M. Cacciari et al.,
hep-ph/
[Xin
disentangling c/b is a must!
e.g. full reconstruction of D vertices
Giuseppe E. Bruno