1. July 13-25, 2000, Hanoi, Vietnam Aurelio Bay Institut de Physique
des Hautes Energies

2. SM g b The Unitary Triangle t d b W (1-r)2+h2 Im ~ (1-r)2 + h2 r2+h2
from Dm:
(1-r)2+h2 Im
~ (1-r)2 + h2
r2+h2
from BÆXu+ln B0
~Vtd
J/Y Ks B0 t
~Vub W W t B0 b g Re
CP Asym ~ sin[2(b+fnew )]
The Unitary Triangle

3. + New FCNC + + b+fnew b+fnew (1-r)2+h2 + rnew d b ~ (1-r)2 + h2
from Dm:
(1-r)2+h2 + rnew + + d b
NEW
FCNC
~ (1-r)2 + h2
r2+h2 = cte
from BÆXu+ln
+ rnew
Unchanged B0 t W t
b+fnew
NEW
b+fnew

4. SM + New FCNC + g b+fnew The Unitary Triangle t d b W (1-r)2+h2 +rnew
from Dm:
(1-r)2+h2 +rnew + Im d b
NEW
FCNC
~ (1-r)2 + h2
r2+h2
from BÆXu+ln
+ rnew B0
J/Y Ks
Unchanged B0
~Vub t W W t B0 g
b+fnew
NEW Re
CP Asym ~ sin(2(b+fnew))
The Unitary Triangle

5. g from Bd Æ D*-np+, D*+np-, etc.
CP in BÆJ/Y Ks ~ 2(b + fnew)
Bd Æ D*+ np vs Bd Æ D*+ np
Bd Æ D*- np vs Bd Æ D*- np
From
2(b + fnew) + g g
Idem with Bs decays:
compare the two
g determinations
(then combine them)
2 ( dg + fsnew ) from CP in Bs Æ J/y f
2 ( dg + fsnew ) - g from CP in Bs Æ Ds-K+, Ds+ K- g
We want to measure g, we need to select hadronic decay channels,
we want to study the Bs system, have K/p separation, access to Br < 10-7….

6. Rate(bb) = 105 sec-1 : 0.5% total inelastic
LHCb overlook
BABAR, BELLE, CLEO-III, CDF, D0, HERA-B will test CKM at the O(l3) level.
LHCb is a second generation experiment for CP violation studies in the B and Bs meson systems. The goal is to obtain precise and overconstrained determination of CKM elements, including terms beyond O(l3). This will permit to detect deviations from the Standard Model description and thus to probe New Physics.
Second generation means:
High statistics is needed to study Bu,d,s decays with Br < 10-7
Excellent proper time resolution
Excellent particle identification
Efficient and flexible triggering scheme, including a selection on hadrons.
High statistics can be obtained by LHCb because
B production cross section at 14 TeV:
LHCb running luminosity: fi
sbb ≈ 500 mb
cm-2 s-1
Rate(bb) = 105 sec-1 : 0.5% total inelastic

7. LHCb non-bending plane view
Magnet
dipole
non-bending
plane view
LHC beams
collide here
Vertex Locator x z
20 m
10 m
Open geometry with (quite) easy access to (almost) all components
q Π[15, 300] mrad
h Π[4.9, 1.9]

8. LHCb bending plane

9. Vertex Locator (VELO) s impact parameter [mm] Z 100 10 0.1 1 10
-20
80 cm
toward
spectrometer
s impact parameter
100 10
[mm]
Pt [GeV] Z
retract by
3 cm during
beam setup cm
sz ≈ 40 mm resolution on
interaction point
• ≈ 200 mm Si single-side
• R and f measuring planes
• 220 kchannels, analogue R/O, S/N =15
Design work on front-end chip (DMILL and sub-micron technolgies) in progress
prototype of R measuring 1/2 plane

10. RICH K–p separation > 3 s 1<p< 100 GeV/c pixel HPD Aerogel
Gas CF4
Gas C4F10
Aerogel
RICH
K–p separation > 3 s
1<p< 100 GeV/c
large
aerogel
rings
small
C4F10
CF4 rings

11. RICH R&D Photodetectors options: HPDs and multianode PMTs
single photoelectron resolution
QE = 17% @ 400 nm
spatial resolution ~1 mm
large area ~2.9 m2, active: ~ 70%
Æ 325 kchan. binary readout
B stray field up to 100 gauss
radiation dose < 3kRad/year
pedestal
1 p.e.
2 p.e.
3 p.e.
4 p.e.
Pion beam:
large rings in aerogel
and small rings in C4F10
threshold
DEP prototype pixel HPD

12. Other Systems Magnet: Warm dipole 4 Tm - 4.2 MW - 1450t TDR ok Tracker
Inner: (40x60 cm2) triple GEM , Si 3 stations
Outer: straw-tube drift chambers
sp/p = 0.3 % [5 , 200] GeV/c
s(MB->pp) =15 MeV/c2
s(MD->KKp) = 4 MeV/c2
Calorimeter (design completed)
Pre-shower sandwich Pb - scintillators
ECAL Shashlik type, 25 X0
HCAL Fe + scintillating tiles, 5.6l
R/O by wave-length shifting fibers and PMTs
MUON
Resistive Plate Chambers (RPC) + Wire and Cathode Pad Chambers (WPC/CPC) for high rate regions

13. Joint Calorimeter Test
HCAL Fe+scintillating tiles
ECAL Shashlik
Joint Calorimeter Test
preshower
GeV
ECAL resolution % 30 20 10
HCAL resolution %
GeV

14. LHCb Trigger Efficiency
for reconstructed and
correctly tagged events
L0(%) L1(%) L2(%) Total(%)
 e h all
BdJ/(ee)KS + tag
BdJ/()KS + tag
BsDsK + tag
BdDK       
Bd + tag
where the lepton
trigger is important
where the hadron
trigger is important
Tags considered (so far):
muon or electron from other b-hadron b Æ lepton
charged kaon from other b-hadron b Æ c Æ s
Overall tag efficiency = 40% Overall mistag rate = 30%

15. Trigger System LHC: 40 MHz L0:1 MHz L1:40 KHz Output:200 Hz
High PT muons
Latency: 4 ms < 2 ms L0
decision
unit
L1 Trigger
3D reconstruction
of secondary vertices
L2+L3 Trigger
Full event
information
High PT electrons
High PT hadrons
Pileup Veto
B0 Æ p+ p-
Running luminosity
2 x 1032
Inelastic pp interactions
hadron trigger
threshold
~30 %
~10%

16. Mass, decay time resolutions and particle ID
Measurements of ms
with a significance >5:
up to psxs
Bs-Bs oscillations with BsDs
Dms = 30 ps-1 
DsK
Ds
GeV/c2
without RICH
with RICH
Bs  DsK
separation from
Bs  Ds
Mass(DsK)
sm = 11 MeV/c2
Ds
DsK
GeV/c2

17. LHCb CP Sensitivities in 1 year
Parameter Channels+c.c No of events (1 year)
 Bd k @P/T = 30°, |P/T|=0.200.02, =90° -5
Bd0  r  k @ =50° 
2+ Bd  D*(incl.) k @2+= 
 BdJ/Ks k <0.6
-2 Bs DsK (Dms=15ps-1)  (45ps-1)
 Bd  DK* 
 Bs  J/ k 
Bs oscillations
xs Bs  Ds k up to 75 (5s)
Rare Decays
Bs   s/b=3.5
Bd K0*  s/b=16
Bd  K*  k s/b=1
See yellow Book CERN !

18. LHCb schedule (and conclusion)
1998 Technical Proposal
1999 LHCb approved
Magnet
2000
RICH, Calorimeters
Outer Tracker
Technical
Design
Reports
Muon System
2001
Vertex Detector
Inner Tracker
2002
L0 & L1 Trigger, DAQ
Computing
2003
Magnet installation
Detector and DAQ installation
2004
2005
LHCb ready for LHC « day one »
and for many years of B physics
at “nominal LHCb luminosity”