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

SM ~V ub     from B  X u + from  m:      B0B0 B0B0 B0B0 J  K s WW t t CP Asym ~ sin[2(  new )] t d b t W W b d ~     ~V td  The Unitary Triangle Im Re

+ New FCNC     = cte from B  X u + from  m:     + r new   new B0B0 W t t ~     d b b d NEW FCNC Unchanged  r new NEWNEW   new  +

SM + New FCNC ~V ub     from B  X u + from  m:     +r new   new B0B0 B0B0 B0B0 J  K s WW t t CP Asym ~ sin(2(  new )) t d b t W W b d ~     d b b d NEW FCNC Unchanged   r new NEWNEW  The Unitary Triangle Im Re

 from B d  D* - n  +, D* + n  -, etc. Idem with B s decays:    s new  from CP in B s  J     s new   from CP in B s  D s  K , D s  K  compare the two  determinations (then combine them) B d  D*  n  vs B d  D*  n  B d  D*  n  vs B d  D*  n  From 2(  new ) +    CP in B  J/  K s ~ 2(  +  new ) We want to measure , we need to select hadronic decay channels, we want to study the B s system, have K/  separation, access to Br < 10  ….

BABAR, BELLE, CLEO-III, CDF, D0, HERA-B will test CKM at the O( 3 ) 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( 3 ). 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 B u,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 LHCb overlook Rate(bb) = 10 5 sec  1 : 0.5% total inelastic  bb ≈ 500  b   cm  s 

LHCb LHC beams collide here Magnet dipole Vertex Locator  Œ  [15, 300]  mrad  Œ  4.9  1.9  x z 20 m 10 m Open geometry with (quite) easy access to (almost) all components non-bending plane view

LHCb bending plane

Vertex Locator (VELO) Design work on front-end chip (DMILL and sub-micron technolgies) in progress prototype of R measuring 1/2 plane cm 0 toward spectrometer retract by 3 cm during beam setup cm ≈ 200  m Si single-side R and  measuring planes 220 kchannels, analogue R/O, S/N =15  z ≈ 40  m resolution on interaction point Z  impact parameter [  m] Pt [GeV]

RICH K–  separation > 3  1<p< 100 GeV/c large aerogel rings small C 4 F 10 CF 4 rings pixel HPD Gas CF 4 Gas C 4 F 10 Aerogel 

pedestal 1 p.e. 2 p.e. 3 p.e. 4 p.e. RICH R&D DEP prototype pixel HPD Photodetectors options: HPDs and multianode PMTs single photoelectron resolution QE = 400 nm spatial resolution ~1 mm large area ~2.9 m 2, active: ~ 70%  325 kchan. binary readout B stray field up to 100 gauss radiation dose < 3kRad/year Pion beam: large rings in aerogel and small rings in C 4 F 10 threshold

Other Systems oMagnet: Warm dipole 4 Tm MW t TDR ok oTracker Inner: (40x60 cm 2 ) triple GEM, Si 3 stations Outer: straw-tube drift chambers  p/p = 0.3 % [5, 200] GeV/c  (M B  ) =15 MeV/c 2  (M D  ) = 4 MeV/c 2 oCalorimeter (design completed) Pre-shower sandwich Pb - scintillators ECAL Shashlik type, 25 X 0 HCAL Fe + scintillating tiles, 5.6 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

HCAL Fe+scintillating tiles ECAL Shashlik Joint Calorimeter Test GeV HCAL resolution % GeV preshower ECAL resolution %

LHCb Trigger Efficiency L0(%)L1(%)L2(%)Total(%)  ehall B d  J/  (ee)K S + tag B d  J/  (  )K S + tag B s  D s K + tag B d  DK      B d     + tag for reconstructed and correctly tagged events where the hadron trigger is important where the lepton trigger is important Tags considered (so far): –muon or electron from other b-hadron b  lepton –charged kaon from other b-hadron b  c  s Overall tag efficiency = 40% Overall mistag rate = 30% Tags considered (so far): –muon or electron from other b-hadron b  lepton –charged kaon from other b-hadron b  c  s Overall tag efficiency = 40% Overall mistag rate = 30%

Trigger System ~30 % ~10% Running luminosity 2 x Running luminosity 2 x LHC: 40 MHz L0:1 MHz L1:40 KHz Output:200 Hz High P T electrons High P T hadrons High P T muons Pileup Veto L0 decision unit L1 Trigger 3D reconstruction of secondary vertices L2+L3 Trigger Full event information Latency: 4  s < 2 ms B 0      Inelastic pp interactions hadron trigger threshold

DsKDsK DsDs GeV/c 2 Mass, decay time resolutions and particle ID  Measurements of  m s with a significance >5: up to  ps   x s  B s -B s oscillations with B s  D s   m s  30 ps  B s  D s K separation from B s  D s  B s  D s K separation from B s  D s  DsKDsK DsDs GeV/c 2  m = 11 MeV/c 2 Mass(D s K) with RICHwithout RICH

LHCb CP Sensitivities in 1 year Parameter Channels+c.c. No of events  (1 year)  B d   P/T = 30°, |P/T|=0.20  0.02,  =90° 2  -5  B d 0     =50° 5  2  +  B d  D*(incl.)   +  =0 12   B d  J/  K s 100k <0.6   -2  B s  D s K  (  m s =15ps -1 ) - 12  (45ps -1 )  B d  DK*   B s  J/  50k 0.6  B s oscillations x s B s  D s  35k up to 75 (5  ) Rare Decays B s   11 s/b=3.5 B d  K 0*  4500 s/b=16 B d  K *  26k s/b=1 See yellow Book CERN !

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