Ulrich Uwer University of Heidelberg On behalf of the LHCb collaboration Beauty 2003, Carnegie Mellon University, Pittsburgh, PA, USA Physics Performance

Physics Goals pure hadronic and multi-body final states. new decay channels in particular B s decays  Study rare and loop-suppressed decays  CPV measurements in many decay channels:  precise determination of CKM elements: measurement of b  u+W (tree) phase  overconstraining the Unitarity Triangles: disentangle the tree phases from phases of oscillations (loops) and penguins 22 B 0 →J/  (  )K 2  +  B 0 →D* _  +  B 0 →D 0 K* 0  and  B 0   +   B s  K + K     B s → D S K  B s → J/  (  )   =  B 0 →  +  ,  W New Physics W Search and filter-out effects of New Physics At 2x10 32 cm -2 s -1  bb pairs produced / yr

Example: New Physics in B mixing Φ d = 2  + Φ d NP Φ s = 2  + Φ s NP CPV inB 0  J/  K s sin(2  +Φ d NP ) B 0  D *  sin(2  +Φ d NP +  ) B s  J/  sin(2  + Φ s NP ) B s  D s Ksin(2  + Φ s NP +  ) Rate of B 0  D 0 K* 0, D 0 K* 0, D 0 CP K* 0  Redundant measurements necessary to disentangle CKM phases from New Physics W New Physics B (s) B (s) mixing phase: Observation of new phase:

Discovery Potential In 1 year: e.g.  (B   D  K *  ):  7 0 sin  d (B 0  J/  K s ):  “reference channel”   2007  BABAR+BELLE 

Monte Carlo Simulation Full Geant 3.2 simulation: PYTHIA 6.2 tuned on SPS(UA5) and Tevatron (CDF) data Multiple pp interactions and spill-over effects included Size of beam spot (  z =5cm) Complete description of material from TDRs Individual detector responses tuned on test beam results Trigger simulation and full reconstruction: Full simulation of L0 and L1 triggers: cuts tuned for max. efficiency at limited output rate (1 MHz L0, 40 KHz L1) Full reconstruction including pattern recognition Simulated samples: Signal samples Background samples: 10 M incl. bb events  4 min 30 M min. bias events  2 sec T1 T2 T3

Detector Performance BsBs KK KK  , K   DsDs D s  mass (GeV) B s  D s   + (K + ) B s vtx z resolution (mm) Proper time resolution (fs) D s vtx z resolution (mm)  core =5.1 MeV

B s  D s  / B s  D s K Separation B s  D s    is a physics background for B s  D s  K  –BR(B s  D s    ) / BR(B s  D s  K  ) ~ 12 –  (B s  D s    ) /  (B s  D s  K  ) = 1% after PID and mass cuts BsDsKBsDsKBsDsBsDs BsDsKBsDsK BsDsBsDs

Event Yield (untagged) Channel  Trig (L0+L1)  tot YieldB/S B0  B0   34 %0.69 % 26 k< 0.7 B 0  K    33 %0.94 %135 k0.16 B s  K -  + 37 %0.55 %5.3 k< 1.3 B s  K  K  31 %0.99 % 37 k0.3 Bs DsBs Ds 31 %0.34 % 80 k0.3 B s  D s -+ K %0.27 % 5.4 k< 1.0 B 0  J /      K S 61 %1.39 %216 k0.8 B 0  J /  e - e   K S 27 %0.16 %26 k1.0 B s  J /      64 %1.67 %100 k< 0.3 B s  J /  e - e   28 %0.32 % 20 k0.7 B 0  36 %0.03 %4.4 k< 7 B 0  K   38 %0.16 % 35 k< 0.7  s  34 %0.22 %9.3 k< year (10 7 s) at L = 2x10 32 cm -2 s -1  tot  det *  rec/det *  sel/rec *  Tri g = 0.12  0.92  0.18  0.34 norm. to 4   ( for B 0      

Flavour Tagging Tag  Tag (%) w (%)  eff (%) Muon Electron Kaon Vertex Charge Frag. kaon (B s ) Combined B 0 (decay dependent: Combined B s trigger + select.) ~4 ~6 l B0B0 B0B0 D   K-K- b b s u s u BsBs ++ Lepton Kaon other B Vertex charge Fragmentation kaon near B s Tagging tracks: large impact par. Kaon tag

Physics Sensitivity –Generate many fast MC samples Signal efficiencies (including tagging) as well as background levels and shapes taken from full simulation studies –extract physics parameter from each sample for CP asymmetries, fit together a second fast MC sample of flavour-specific decays to extract the mistag “from the data” Reference measurements:sin(2  ) from B 0  J/  K s  m s from B s  D s  CPV measurements:sin(2  ) and  s from B s  J/  B s  D s K  from B 0  and B s  KK B 0  D 0 K *0 Radiative decays:b  s  penguins CP reach evaluation: all numbers for 1 yr

sin  d in B  J/  K s sinΦ d = sin(2  ) A dir  0  New Physics beyond SM Annual B 0  J/  (  )K s yield: 216k Background: B/S 0.8 Tagging probability: 45 % Mistag probability w : 37 % MC simulation of many experiments:  (sin(  d )) = (“measurement” of mistag rate w through simulated B 0  J/  (  )K* evts)

 m s with B s  D s + (KK  )  - Expected unmixed B s  D s    sample in one year of data taking (fast MC) Annual event yield: 80k Background B/S: 0.32 Tagging probability: 55 % Mistag probability w : 33 % Proper time res. 33 fs (core)  m s (ps -1 ) (ms)(ms) Statistical precision / yr 5  observation of B s oscillation: 68 ps -1 / yr error  A of oscillation amplitude

and  Γ s with B s  J/  Φ Φ s and  Γ s with B s  J/  Φ The “gold plated decay” of B s : SU(3) analogue of B d  J/  K s A CP in SM  Φ s = -2  = -2 2  ~ Problem: PS  VV 3 contributing amplitudes 2 CP even, 1 CP odd  fit angular distribution of decay states (transversity angle  tr ) as function of proper time. event yield (  ) / yr: 100k background B/S: <0.3 tagging efficiency 50% Mis-tag rate: 33% proper time resolution 38 fs If  Γ/Γ is ~0.1, can do a 5  discovery in one year  (  ) ~ 2 O

 from B s  D s  + K +  Time dependent B s  B s asymmetries 5 yrs of data,  m s =20 ps -1 Interference between 2 tree diagrams due to B s mixing Measure    s from time- dependent rates: B s  D s  K  and B s  D s  K  (+ CP-conjugates) B s  J/  Use  s from B s  J/  After 1 year, if  s/  s = 0.1, 55 <  < 105 O  20 <  T1/T2 < 20 O msms (+Φs)(+Φs) event yield (  ) / yr: 5.4k background B/S: <1.0 tagging efficiency 54% Mistag rate w : 33% (extract from B s  D s  ) No theoretical uncertainty; insensitive to new physics in B mixing

 from B      and B s  K  K  Measurement of time-dependent CP asymmetry for both decays  A dir and A mix w/ strong phase contribution of unknown magnitude A dir (B 0   +  - ) = f 1 (d,,  ) A mix (B 0   +  - ) = f 2 (d,, ,  d ) A dir (B s  K + K  ) = f 3 (d’, ’,  ) A mix (B s  K + K  ) = f 4 (d’, ’, ,  s ) U-spin symmetry:d = d’ and = ’ In both decays large b  d(s) penguin contributions to b  u: Method proposed by R. Fleischer: use B      and B s  K  K  together exploit U-spin flavour symmetry for P/T ratio described by d and 4 measurements (CP asymmetries) and 3 unknown ( , d and )  can solve for  Φ s (B s  J/  ) Φ d (B 0  J/  K s ) d d

 from B      and B s  K  K  68% and 95% CL regions (for  input = 65 deg) “fake” solution d vs  A dir , A mix , A dir KK, A mix KK and w (mistag), A  K,,, A  K,,,  Γ,  m, Γ, m and  resolutions (17 par.) from fit to: B      (26k / yr) B s  K  K  (37k / yr) B   K +   (135k / yr) B s  K   + (5.3k / yr)  p.d.f. F(d,,  ) B   (95%CL) B s  K  K  (95%CL)  (  ) = 4  6 deg If  m s = 20 ps  1,  s /  s =0.1, d =0.3, = 160 deg, 55 <  < 105 deg: U-spin symmetry assumed; sensitive to new physics in penguins

 from B   D  K *  and B   D  K *  A 1 = A 1 √2 A 3 A2A2 A2A2 22  Variant of the Gronau-Wyler method proposed by I.Dunietz: A ( B   D CP K *  ) = A 3 = 1/  2 ( A(B   D 0 K *  ) + A(B   D 0 K *  ) ) 1/  2 ( A 1 + |A 2 | e i (  +  ) ) together with CC decays  two triangle relations for amplitudes Measure 6 decay rates: yield/yrB/S B   D 0 (K   + ) K *  (K +   ) 0.5k1.8 B   D 0 (K +   ) K *  (K +   ) 3.4k0.3 B   D CP (KK) K *  (K +   ) 0.6k <  < 105 deg  20 <  < 20 deg  (  ) = 7  8 deg sensitive to new phase in D CP + cc  =65 o,  =0

B 0  K *0  and B s   W b u,c,t s In SM:  loop-suppressed b  s  transitions  BR( B 0  K *0  ) = (4.3  0.4)  expected direct CP violation <1% for B 0  K *0   expected CP violation in mixing ~0 for B s   1 yrB/S B 0  K *0 (K +  - )  35k<0.7 B s  (K + K - )  9.3k<2.4  (A CP ) ~ 0.01 (1year)  ~64MeV  ~65MeV

B 0  K* 0  +  - SM: BR(B 0  K* 0  +  -) = (1.2  0.4) x  Measurement determines |V ts| Variables sensitive to New Physics:   +  - invariant mass distribution   +  - forward-backward asymmetry  FBA =  (  +, B direction in  +  - CMS) Annual yield (SM): 4.4k Efficiency:0.7% Background (B/S) <2  (BR) ~ 3%  (A CP ) ~ 3%

Conclusion LHCb can study many different B-meson decay modes with high precision  excellent particle identification capability  excellent mass and decay-time resolution LHCb can fully exploit the large B-meson yields at LHC from the start-up  flexible, robust and efficient trigger  design luminosity of 2x10 32 is lower than typical LHC luminosity LHCb detector will be ready for data taking in 2007 at LHC start-up  detector production is on schedule  installation of detectors will start end of next year LHCb will offer soon an excellent opportunity to  determine precisely the CKM parameters through phase meas.  spot New Physics by overconstraining the Unitarity Triangles