M. Adinolfi - University of Bristol1/19 Valencia, 15 December 2008 High precision probes for new physics through CP-violating measurements at LHCb M. Adinolfi University of Bristol On behalf of the LHCb collaboration

M. Adinolfi - University of Bristol2/19 Valencia, 15 December 2008 Introduction LHCb is a 2 nd generation precision experiment following Tevatron and the B-factories b -> c transitions: extensively studied and in good agreement with SM b -> s transitions: limited knowledge, room for NP effects Precision measurements available for CKM parameters, allowing strong constraints on SM, but  still poorly measured. Collection of large sample of b (c) hadrons at LHC allows extensive study in a wide set of channels. Rare decays - see Hugo Ruiz presentation Early LHCb results - see Abraham Gallas presentation B s mixing  with trees  with loops Mixing and CPV in charm

M. Adinolfi - University of Bristol3/19 Valencia, 15 December 2008 LHCb in a nutshell Real beam gas event High statistics:  L ~ 2 x cm -2 s-1  bb ~ 500  b at 14 TeV ~ bb year (2 fb -1 ) B ±, B 0, B s, B c,  b … Tracking: Mass resolution:  B(D) ~ 15(7) MeV B vertex resolution:  z ~ 200  m Proper time resolution:   ~ 40 fs Particle identification:  /K separation over 2 GeV < p < 100 GeV Trigger: First level (L0) High p T hadron trigger

M. Adinolfi - University of Bristol4/19 Valencia, 15 December 2008 B s phase  s B s -> J/Ψ  dominated by tree NP can enter through mixing B s ->  dominated by a penguin NP can enter through mixing and/or penguin In presence of NP the mixing phase Is modified and can probe NP in the mixing (  M NP ) and/or the penguin (  D NP ). Tevatron results: D0  s =  with 2.8 fb -1 CDF  s = 68%CL with 1.35 fb -1 The observable is  s =  SM +  NP In SM  S (B s -> J/Ψ  ) = -2  s = ±   s (B s ->  ) = 0

M. Adinolfi - University of Bristol5/19 Valencia, 15 December 2008 B s phase  s (2)  s can be extracted from CP time-dependent asymmetry in decay rates : with n f = ±1 CP eigenstate Would like to use pure CP eigenstates such as B s  J/Ψ η, B s  J/Ψ η’, B s  η c Φ, B d  D s + D s - But low yield and high background B s -> J/Ψ  has a nice signature and large yield small background but is a mixture of CP = +1 and CP = -1 states requires an angular analysis to disentangle the two states Combined D0 and CDF 2.2  from SM (ICHEP08)

M. Adinolfi - University of Bristol6/19 Valencia, 15 December 2008 B s phase  s (3) Similar analysis yields 3.4k events (2 fb -1 ) with an expected sensitivity on  s B s ->   (  s ) ~ k 0.03

M. Adinolfi - University of Bristol7/19 Valencia, 15 December 2008 Angle   plays a unique role in flavour physics Can be measured through tree diagrams and those involving loops Trees Benchmark for SM Time integrated (GLW, ADS, Dalitz/GGSZ) and/or time dependent strategies Loops Sensitive to NP Measured at B factories A full test of SM and unitarity requires:   ~ a few degrees measurement in B ±, B 0 and B s  = 77° + 30° - 32°

M. Adinolfi - University of Bristol8/19 Valencia, 15 December 2008 GLW method: f D is a CP eigenstate common to D 0 and D 0 : f D = K + K -,  +  -,… Measure: B → D 0 K, B → D 0 K, B → D 1 K Large event rate; small interference Measurement r B difficult  from trees: B -> DK B–B– D0K–D0K– D0K–D0K– fDK–fDK– b  c favoured b  u suppressed Decay time independent analysis Cabibbo supp. Cabibbo allowed. Interfere decays b  c with b  u to final states common to D 0 and D 0 color suppression ADS method: Use common flavour state f D =(K +  – ) Note: decay D 0 → K +  – is double Cabibbo suppressed Lower event rate; large interference 8

M. Adinolfi - University of Bristol9/19 Valencia, 15 December 2008  from trees: B ± -> D(hh) K ± ChannelYield (2 fb -1 )B/S B + → D(K  ) K + Favoured 28 k0.6 B + → D(K  ) K + Suppressed B + → D(KK) K + Favoured3k1.2 B + → D(  ) K + Suppressed 1k3.6 ADS and GLW 6 rates, 5 unknown parameters Assuming:  = 60° r B = 0.10  B = 130° (PDG) r D = (PDG)  D centered at 158° (ADS requires -180 shift w.r.t. published  D from CLEO-c)   = 10.8° – 12.7° depending on  D

M. Adinolfi - University of Bristol10/19 Valencia, 15 December 2008  from trees: Combining all ADS - GLW   = 7° – 9.5°

M. Adinolfi - University of Bristol11/19 Valencia, 15 December 2008  from trees: B ± -> D(K s  +  - ) K ± K s  +  - Dalitz plot contain a CP-violating contribution from the decay path sensitive to  Two different method of analysis Unbinned fit based on amplitude model Model independent binned fit using ψ(3770) results on D decays. Background suppressed with RICH and momentum cut Yield ~ 5k per year Statistical uncertainty   = 9.8° Amplitude model   = 12.8° Binned fit Amplitude model also affected by uncertainty due to the model. Latest BaBar analysis estimate 7° Binned fit affected by finite statistics in Ψ sample, estimated 2°.

M. Adinolfi - University of Bristol12/19 Valencia, 15 December 2008  from trees: B s -> D s K Interference between tree decays via mixing Insensitive to NP Measures  +  s (  s measured from B s ->J/Ψ  ) Include B s ->D s  to determine  m s and tagging dilution Simultaneous fit to both decays Assuming  = 60° and  m s = 17.5 ps -1 B s → D s - K + ChannelYield (2 fb -1 )B/S B s → D s K6.2 k0.7 B s → D s  140 k0.2    = 10.3°

M. Adinolfi - University of Bristol13/19 Valencia, 15 December 2008  from loops: B -> hh B d/s  /K B d/s Interference between tree and penguin diagrams Measure time-dependent CP asymmetries for B 0     and B s      Assume U-spin flavour symmetry (d  s) d = d’ and  =  ’ Take  d from B d  J/  K s and  s from B S  J/  solve for  4 observables, 3 unknowns

M. Adinolfi - University of Bristol14/19 Valencia, 15 December 2008  from loops: B -> hh (2) Bs  K+K- BG     2 fb -1  ms=20 Time  14 ChannelYield (2 fb -1 )B/S B s → KK36 k< 0.06 B 0 →  36 k0.5 WITH RICH PID NO PID

M. Adinolfi - University of Bristol15/19 Valencia, 15 December 2008 Different ways to measure  B modeD modeMethodParameter Bs→DsKBs→DsK KK  tagged, A CP (t) -s-s B + → D K + K ,KK/  counting, ADS+GLW  B + → D K + K s  Dalitz, GGSZ  B + → D K + KK  4 body Dalitz  B 0 → D K *0 K ,KK,  counting, ADS+GLW  B → ,KK -tagged, A CP (t)  /  d /  s   2fb -1 9°-12° 11º-13º 10º-13º 18º 5º-12° 4º  B ° (°) Combined B + /B 0 (ADS+GLW) 4.6°7.6°6.3°7.1°4.6° + model independent Dalitz4.1°5.1°4.8°5.1°3.9°   2fb -1 Combining with time dependent measurements a global sensitivity with tree decays only in 2 fb -1   ~ 4°

M. Adinolfi - University of Bristol16/19 Valencia, 15 December 2008 Charm physics – Trigger and yields Dedicated D* -> D 0 (hh)  trigger stream Loose cuts on hadrons pt, IP, D0 mass, D* - D0 mass difference RICH information not used in the trigger Present selection favours D* coming from B decays Estimated yields for secondary D 0 for 2 fb -1 D 0 -> K -  + (right sign) 12.4 M D 0 -> K +  - (wrong sign) 46.5 K D 0 -> K + K M D 0 ->  +  M Similar amounts expected for prompt production.

M. Adinolfi - University of Bristol17/19 Valencia, 15 December 2008 Charm physics - D 0 mixing Sensitive to NP in the box diagram loop Recently observed at BaBar Belle and CDF x = 0.89± % y = 0.75± % Time-dependent D0 mixing with wrong-sign D 0  K +  – decays  stat (x’ 2 ) ~0.14 x10 –3,  stat (y’) ~2 x10 –3 with 2 fb –1 D unambiguously tagged at production by the sign of the slow  in the D* decay

M. Adinolfi - University of Bristol18/19 Valencia, 15 December 2008 Charm physics – Direct CP violation Direct CP violation can be measured in D 0  KK lifetime asymmetry ACP<10 -3 in SM, up to 1% with New Physics current HFAG (average Belle, BaBar, CDF): ACP = ± 0.23 Expect  stat (ACP) ~ with 2 fb –1

M. Adinolfi - University of Bristol19/19 Valencia, 15 December 2008 Conclusions LHCb is a heavy flavour precision experiment searching for New Physics in CP Violation and rare decays CP Violation: 2 fb -1 (1 year)  from trees: 4 o  from loops:  10 o  B s mixing phase: 0.023