Physics Analysis Planning for LHCb

NIKHEF Jamboree, December Summary of current CKM results… (2005) CKM is a coherent picture of CP violation within the SM New Physics will (most likely) appear as corrections on the CKM framework. or appear in places we haven’t looked (yet) ;-) Mission Statement: CKM metrology: determine magnitude and phase of coupling constants of the charged weak interactions possibly in the presence of NP Identify (or put limits on) the effects of NP on flavour physics observables

NIKHEF Jamboree, December CKM metrology in presence of NP Drop all observables which depend on loop diagrams, as there could be (hopefully!) competing New Physics amplitudes… i.e. those which includes V td (or V ts ) Only these two are left: phase and magnitude of V ub /V cb |V ub /V cb | seems mission impossible for LHCb If anyone has suggestion on how LHCb could compete here, please let me know!

NIKHEF Jamboree, December Arg(A BB )=2  +2  Bd Testing for NP in B d mixing SM NP Disfavored by A sl  d =0  NP phase = SM phase (Minimal Flavour Violation Scenarios) φ Bd = -4.7 ± 2.3; [-9.9,1.0] at 95 % C.L. C Bd = 1.27 ± 0.44; [0.56,2.51] at 95 % C.L. Tree processes : NP free  NP should still satisfy these constraints!

NIKHEF Jamboree, December Tree processes : NP free Testing for NP in B s mixing SM ? I want you to measure A cp (B s  J/  ) I want you to measure  m s

Remember B 0 d oscillations:  Predicted heavy particle…  m top >50 GeV Needed to break GIM cancellations B s –B s oscillations: “Box” diagram –  m s SM  |V ts | 4 Size of the Box: B s mixing ( Δ m s ) Phys.Lett.B192:245,1987 New particles can augment the SM Box:  m s  |V ts 2 +A NP | 2 ? b s s b

B s Mixing Phase : B s  J/ ψφ Δm s is sensitive to | A ( B s   B s )| We can also probe the phase of A ( B s   B s )  Interference of amplitudes sin φ SM = - Aηλ 4 / Aλ 2 = -ηλ 2   Any larger asymmetry means new physics… Ball et al, Phys.Rev.D69(115011),2004 hep-ph/ Dunietz et al, Phys.Rev.D63(114015),2001 hep-ph/ b s s b +

Example NP model: SUSY SO(10) Chang, Masiero, Murayama Phys.Rev.D67 (075013), 2003, hep-ph/ Y U contains the large top coupling Y U can be symmetric. In Y u diagonal basis we have: Superpotential: (16 are fermions, 10 Higgses) Break to SU(5) Break to MSSM (+rh ν ): Without neutrino mass, U MNS could be rotated away Neutrino mixing angle bRbR ~ Just as in the SM, we rotate the d-quarks

Consequences of SO(10) GUT and (d r R,d b R,d g R, ν L,L ) multiplets :  No effect in s R ↔ b R (i.e. CKM), because there is no right handed coupling  Observable effects in mixing between s̃ ↔ b̃ The Box Diagram (Δ B=2 ): –B s mixing: B s  D s - π + –CP phase: B s  J/ ψφ Penguins & Rare decay (Δ B=1 ) : –Rare decays: B  K * μ + μ - –B (s)  μ + μ - SUSY SO(10): neutrino mixing  squark smixing

Not just SUSY can cause effects…

Rare decays: B (s)  μ + μ - & B  K * μ + μ - s̃ ↔ b̃ also appears in Penguin Diagram  Affects rare decay B 0  K * μ + μ - Blazek,Dermisek,Raby Phys.Rev.D65(115004),2002 hep-ph/ Dedes,Dreiner,Nierste Phys.Rev.Lett.87(251804),2001 hep-ph/ The “smoking gun” of SO(10) Yukawa unification... s s μ-μ- μ-μ- μ+μ+ μ+μ+ μ+μ+ μ-μ- s̃ Tevatron: BR < SM: BR=  Similarly, B s  μ + μ - is very promising SO(10) unifies fermion masses, and predicts:  tan β = m t (M Z )/m b (M Z )~ Ali et al Phys.Rev.D61(074024),2000, hep-ph/ Babu,Kolda Phys.Rev.Lett.84(228),2000 hep-ph/ b s

NIKHEF Jamboree, December Context: Some History

NIKHEF Jamboree, December Additional physics within LHCb: Time-Dependent CP in B 0 ‘b  c(cs)’ (reference beta) Time-Dependent CP in B 0 ‘b  s(ss)’ (beta with penguins) Time-Dependent CP in B 0 ‘b  u’ (alpha) Two body Quasi Two body Three body … Direct CP in Two-Body ‘b  u’ decays, both B 0 and B s Sensitive to gamma (if s↔d symmetry holds) B 0  D(*)K(*), B +  D(*)K(*) (ADS,GLW, Dalitz, … ) Current world’s best  constraint… But maybe it is based on an upward fluctation of r… Radiative B-decays (b  s , b  d  ) Could determine |V ts /V td | without measuring  m s Mixing and CP in D-decays Any non-zero observation would be NP… …

NIKHEF Jamboree, December A Theoreticians (G. Isidori) Shopping List

Four Lines of Attack on “b  s” 1)A mix (B s  D s  )  A cp (B s  D s K) 2)A cp (B s  J/  ) 3)Br(B (s)   ) 4)A fb (B 0  K ( * )  ), A fb (b  s  ) This list does NOT include intermediate ‘stepping stones’ or (sometimes very interesting) spin-off These subjects exploit LHCb advantages over other experiments: a.B s mesons (1-3) b.large production rate (4) c.all charged final states d.dedicated triggers e.propertime resolution f.momentum resolution g.PID, tagging And are well matched to our construction and reconstruction activities: i.OT construction ii.VELO construction iii.Track reconstruction b s b s s b

Organisation 1)A mix (B s  D s  )  A cp (B s  D s K) 1—2 staf, 1 PostDoc, ~3 OIO 2)A cp (B s  J/  ) 1—2 staf, 1 PostDoc, ~3 OIO 3)Br(B s   ) 1—2 staf, 1 PostDoc, ~2 OIO 4)A fb (B 0  K ( * )  ), A fb (b  s  ) 1—2 staf, 1 PostDoc, ~2 OIO

1) Open Charm and 2) Charmonium B +  J/  K + and  2S)K +,  2S)   +  and J/  + , J/    +  - B +  D 0  + and D 0 a 1 + and D 0  + D 0  K +  - a 1 +   +  -  + B 0  J/  K* 0 and  2S)K* 0 K* 0  K +  - B 0  D *+  + and D *+ a 1 + and D *+  + D *+  D 0  + B s  J/  and  2S)    K + K - B s  D s  +,and D s a 1 + and D s  +, D s   +,and K* 0 K - and K + K -  + and  B c  B s (J/  )  and D s J/  and J/ 

Timeline 1 & A cp (J/  ) 9 PID A 0,A //,A ┴ triple product  msms 7 Tagging Time Lifetime ratios,  1)Select exclusive B  J/  X 2)Select exclusive B  D (s) (*) , D (s) (*)  3)Determine propertime resolution with exclusive J/  X 4)Determine propertime resolution & trigger efficiency vs. propertime for/with D (s) (*)  D (s) (*)  5)Angular analysis B 0  J/  K* and B s  J/  6)Measure lifetime ratios with exclusive J/  X 7)Determine tagging performance, measure/limit  m s 8)B s  J/  tagged time- dependent transversity & CP 9) B s  D s (K/  ) tagged time- dependent CP

3) B  K*  and 4) B (s)   J/  K* and  (2S)K* are both background & calibration sample for K*  J/    gives normalization for Br(B (s)   ) Both channels need excellent vertex (VELO) and momentum resolution (OT) to select signal and reject background (due to lack of intermediate resonances) )Select inclusive J/  2)Select exclusive B  J/  X 3)Determine propertime resolution with exclusive J/  X 4)Angular analysis B 0  J/  K* and B s  J/  5)Selection of K*  6)Selection of B (s)   7)Determination Afb(K*  ) 7 6 1

We have defined a physics analysis roadmap Focus on b  s transition in a way which profits from LHCb strong points And which covers both ‘CKM metrology’ and ‘Physics Beyond SM’ discovery Roadmap matches our (re)construction efforts Large part of our plan is well established within the LHCb collaboration –See eg. Reoptimization TDR And is embedded within LHCb collaboration –GR convener ‘propertime & mixing’ physics group & member ‘Physics Planning Group’ Summary & Conclusions routemap Routemap

BACKUP

Strengths of indirect approach Can in principle access higher scales and therefore see effect earlier: –Third quark family inferred by Kobayashi and Maskawa (1973) to explain small CP violation measured in kaon mixing (1964), but only directly observed in 1977 (b) and1995 (t) –Neutral currents ( +N  +N) discovered in 1973, but real Z discovered in 1983 Can in principle also access the phases of the new couplings: –NP at TeV scale needs to have a “flavour structure” to provide the suppression mechanism for already observed FCNC processes  once NP is discovered, it is important to measure this structure, including new phases Complementarity with the “direct” approach: –If NP found in direct searches at LHC, B (as well as D, K) physics measurements will help understanding its nature and flavour structure  this workshop to explore such complementarity

VELO TT T1 T2 T3 RICH2 RICH1 Magnet PYTHIA+GEANT full simulation Expected LHCb tracking performance 10 mm MC truth 100  m oHigh multiplicity environment: —In a bb event, ~30 charged particles traverse the whole spectrometer MC truth Reconstructed oFull pattern recognition implemented: —Track finding efficiency > 95% for long tracks from B decays (only 4% ghosts for p T > 0.5 GeV/c) —K S  +  – reconstruction 75% efficient for decay in the VELO, lower otherwise

Expected tracking performance Proper time resolution: ATLAS:  t ~ 100 fs (was 70 fs) CMS:  t ~ 100 fs LHCb:  t ~ 40 fs B s  D s  proper time resolution  t ~ 40 fs Mass resolutions in MeV/c 2 ATLAS CMS LHCb B s   Bs Ds Bs Ds  46–14 B s  J/   B s  J/   Good proper time resolution essential for time- dependent B s measurements ! without J/  mass constraint with J/  mass constraint

—S/B ~ 3 (derived from 10 7 fully simulated inclusive bb events) B s oscillations oMeasurement of  m s is one of the first LHCb physics goals —Expect 80k B s  D s   + events per year (2 fb –1 ), average  t ~ 40 fs Distribution of unmixed sample after 1 year (2 fb –1 ) assuming  m s = 20 ps -1  5  observation of B s oscillations for  m s < 68 ps – 1 with 2 fb –1 LHCb

B s oscillations oCurrent SM expectation of  m s (UTFit collab.): oLHC reach for 5  observation: ATLAS/CMS30 fb –1 3 years LHCb0.25 fb –1 1/8 year

 s and  s from B s  J/ , … B s  J/  is the B s counterpart of B 0  J/  K S : –B s mixing phase  s is very small in SM:  s = –arg(V ts 2 )=–2  2 ~ –0.04  sensitive probe for new physics –J/  final state contains two vectors: Angular analysis needed to separate CP-even and CP-odd Fit for sin  s,  s and CP-odd fraction (needs external  m s ) Sensitivity (at  m s = 20 ps –1 ): –LHCb: 125k B s  J/  signal events/year (before tagging), S/B bb > 3   stat (sin  s ) ~ 0.031,  stat (  s /  s ) ~ (1 year, 2 fb –1 ) can also add pure CP modes such as J/ , J/  ’,  c  (small improvement)   stat (sin  s ) ~ (first 5 years)  will eventually cover down to ~SM –ATLAS: similar signal rate as LHCb, but  stat (sin  s ) ~ 0.14 (1 year, 10 fb –1 ) –CMS: > 50k events/year, sensitivity study in progress

Exclusive b  s     s = (m  ) 2 [GeV 2 ] A FB (s) for B 0  K *0  s = (m  /m  b ) 2 ^ A FB (s) for  b  +  – ^ MSSM C 7 eff >0 ATLAS expectation for 30 fb –1 SM oLHCb: —4400 B 0  K * 0     events/2fb –1, S/B > 0.4 —After 5 years: zero of A FB (s) located to ±0.53 GeV 2  determine C 7 eff /C 9 eff with 13% error (SM) oATLAS: —1000 B 0  K * 0     events/10fb –1, S/B > 1 oOther exclusive b  s  feasible (B s,  b ) oSuppressed decays, SM BR ~ 10 –6 oForward-backward asymmetry A FB (s) in the  rest-frame is sensitive probe of New Physics: —Zero can be predicted at LO with no hadronic uncertainties, depends on Wilson coefficients

Bs  +–Bs  +– oVery rare decay, sensitive to new physics: —BR ~ 3.5  10 –9 in SM, can be strongly enhanced in SUSY —Current limit from Tevatron (CDF+D0): 1.5  10 –7 at 95% CL oLHC should have prospect for significant measurement, but difficult to get reliable estimate of expected background: —LHCb: Full simulation: 10M inclusive bb events + 10M b , b  events (all rejected) —ATLAS: 80k bb  events with generator cuts, efficiency assuming cut factorization —CMS: 10k b , b  events with generator cuts, trigger simulated at generator level, efficiency assuming cut factorization —New assessment of ATLAS/CMS reach at cm –2 s –1 in progress 1 year B s   +  – signal (SM) b , b  background Inclusive bb background All backgrounds LHCb2 fb –1 17< 100< 7500 ATLAS10 fb –1 7< 20 CMS (1999)10 fb –1 7< 1