1. Overview of LHCb Poland Ukraine Brazil UK Switzerland France Spain
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QCD AND HIGH ENERGY HADRONIC INTERACTIONS
Spectroscopy
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Overview of LHCb
On behalf of the LHCb Experiment

2. Overview of LHCb Contents : - Physics Motivations - LHC environment
- LHCb expected performance
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Overview of LHCb

3. - NP could still be hidden in box and loop diagrams
Physics Motivations
CKM fit (ICHEP 2004)
- BABAR, BELLE, Tevatron and kaon experiments have tested and will test CKM picture of CP violation (no clear hint of NP for the moment) b s
B0s
New particles
- NP could still be hidden in box and loop diagrams
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Overview of LHCb

4. Physics Motivations LHCb will study all types of B mesons ! B0d system
B0s system
B0 -> rr,pp,rp (s(a)~5-100)
B0s -> J/yf,ff
B0 -> J/y Ks, J/yp0,fKs (s(b)~0.70)
B0 -> DK*, D* (s(g)~ )
B0s -> DsK, KK
(Expected sensitivities of B factories in 2007)
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Overview of LHCb

5. LHC environment PYTHIA LHC : pp collisions at s = 14 TeV (40 MHz)
bb pairs are mostly produced at small angles wrt beam pipe > forward spectrometer
L = cm-2s-1
to avoid high number of interaction / bunch crossings : L = cm-2s-1 for LHCb
--> simpler events and less radiation damage for the detectors
sinelastic  80 mb and sbb  0.5 mb
--> need an efficient trigger
but Nbb (1 year in 4p) = 1012
with B+ / B0d / B0s / b-baryon
(4 : : 1 : 1 )
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Overview of LHCb

6. Trigger multi-level trigger : - Level 0 (40 MHz --> 1 MHz):
reject complicated events
high pT e, g, p0,m, or hadrons
- Level 1 (1 MHz --> 40 KHz):
large IP and pT tracks
- HLT (40 KHz --> 200 Hz):
access to complete events
~ offline selection
+ 1.8 KHz to get systematics from data
high dimuon mass --> tracking
inclusive b (bm) --> trigger + data mining
D* > PID
HCAL trigger
dominates
MUON trigger
ECAL trigger
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Overview of LHCb

7. LHCb detector requirementsK-
few mm
B0s K+ p p
Primary vertex
Efficient particle identification :
- p/K separation (1-->100 GeV) --> RICH (for B0(s) --> hh, flavour tagging, …)
- electron and muon ID --> CALO + MUON (for B0(s) --> J/y X, flavour tagging, …)
Good decay time resolution (~ 40 fs):
- vertex detector (for B0s --> Dsp, B0s --> J/y f, ...)
The best mass resolution and efficient tracking :
- tracker and magnet
magnet
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Overview of LHCb

8. LHCb experiment Single arm forward spectrometer Acceptance side view
250/300 mrad
v / h
Acceptance
10 mrad
pp collision
side view
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Overview of LHCb

9. Vertex Locator PV position resolution : IP precision : Vacuum vessel
Vertex and tracking detector :
- silicon discs
- 8 mm from beam axis
- 21 stations (retractable)
Interaction region
stations
PV position resolution :
~ 8 mm (x,y) and ~ 44 mm (z)
IP precision :
~ 40 mm
Vacuum vessel
1 m
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Overview of LHCb

10. Bs oscillation frequency Dms
LEP + SLD -> ms> 14.4 ps-1
Important physics subject of CDF+D0
Needed for the observation of CP asymmetries with Bs decays
Use Bs Ds (~80k evts/year expected)
If ms= 20 ps1 (ms) = ps1
Can observe 5 oscillation signal if ms < 68 ps1 (well beyond SM prediction)
Propertime resolution :
Expected unmixed Bs Dssample in one year of LHCb data taking
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Overview of LHCb

11. RICH
B0s --> KK
B0s --> KK
2 RICHs and 3 Cherenkov radiators to cover the full momentum range
good p/K separation for 2<p<100 GeV
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Overview of LHCb

12. Calorimeter System SPD/PS (2X0) ECAL (25X0) : lead/scintillator
With Bremsstrahlung recovery
SPD/PS (2X0) ECAL (25X0) : lead/scintillator
HCAL (5.7l) : iron/scintillator
Readout every 25 ns (L0 trigger)
Identification : electrons, hadrons and p0
ECAL : sE/E ~ 10% / E  1%
HCAL : sE/E ~ 80% / E  10%
e e e ~ 94% ande p  e ~ 0.7% for tracks in ECAL acceptance
(~ 60 MeV/c²)
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Overview of LHCb

13. Muon System
( ~ 10 MeV/c²)
5 stations with 1380 MWPCs
Projective geometry
Each station subdivided into four regions
em m  ~ 93 % ep  m  ~ 1.0 % for tracks in Muon detector acceptance
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Overview of LHCb

14. I will give more details hereafter
Many Physics Topics at LHCb
- Measurement of a angle
B -> rp (12k evts/year) s(a) < 100 (1 year)
- Measurement of b angle
B -> J/yKs (240k evts/year) s(b) ~ 0.70 (1 year)
- Measurement of g angle
with Bs->DsK, B->pp and Bs->KK, B->DK* decay
- Measurement of Bs mixing angle c
with Bs->J/yf decay
- New physics in b -> s penguin process
B -> K*g , B -> fKs , Bs -> ff, fg
D physics
Mixing, CPV
- Rare decays
Bs -> mm, B -> K* mm
- Bc physics, b baryons
lifetimes, masses, branching ratios
I will give more details hereafter
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Overview of LHCb

15. B0s Mixing Phase (c)
- needed for some g measurements
- use Bs->J/yf (~120k evts/year expected)
Angular analysis to separate
CP even and CP odd
Propertime resolution
st = 38 fs
s(sin 2c)~0.06 and s(DGs/Gs)~ (with Dms = 20 ps-1)
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Overview of LHCb

16. Measurements of angle g : possible scenario
1. Bs->DsK
(s(g)14-150)
2. B->pp, Bs->KK
(s(g)4-60)
3. B->DK*
(s(g)7-80)
g affected by possible
new physics in
D-D mixing
g not affected by new physics in loop diagrams
g affected by possible
new physics in penguin
Determine the CKM parameters A, r, h independent of new physics
Extract the contribution of new physics to the oscillations and penguins
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Overview of LHCb

17. Conclusion LHC offers great opportunity for B physics
LHCb is dedicated to b Physics with
Efficient trigger for b physics
Excellent vertex and momentum resolution
Excellent particle identification
Access to all b-hadron species
Promising potential for studying New Physics
Construction of the experiment is on the way…
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Overview of LHCb

18. Hervé Terrier
Overview of LHCb

19. Back Up Slides
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Overview of LHCb

20. Adding  and  measurements
CKM fit (ICHEP 2004)
Adding  and  measurements
Adding  measurements
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Overview of LHCb

21. RICH PID performance
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22. Bs -> DsK diagrams B0s D-s K+ s b c W+ u B0s D-s K+ W- b s u c B0s
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Overview of LHCb

23. B0d(s) -> hh diagrams
p-(K-)
p+(K+)
d(s) b u W d
(s)
d(s) W b u c t g
B0d(s)
p-(K-)
p+(K+)
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Overview of LHCb

24. B0d-> DK* diagrams B0d W b c d s u K*0 D0 B0d W b u d s c K*0 D0
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Overview of LHCb