LHCb expected physics performance with 10 fb –1

1. LHCb Upgrade Workshop Edinburgh, January 11–12, 2006 LHCb expected physics performance with 10 fb–1 Olivier Schneider Laboratoire de Physique des Hautes Energies (LPHE) Olivier.Schneider@epfl.ch

2. bb angular correlation in pp collisions at s = 14 TeV (Pythia) (unchanged since more than a decade) The whole idea • Given the fact that • LHC will be the facility producing the largest number of b hadrons (of all types), by far, and for a long time • the Tevatron experiments have demonstrated the feasibility of B physics at hadron machines  perform a dedicated B-physics experiment at the LHC,but with a new challenge: • exploit the huge bb production in the not-well-known forward region, despite the unfriendly hadronic environment (multiplicity, …) for B physics • ~ 230 b of bb production in one of the forward peaks (400 mrad),corresponding to nearly 105 b hadrons per secondat a low luminosity of 21032 cm–2s–1 LHCb Upgrade Workshop, Edinburgh

3. VELO: Vertex Locator (around interaction point) TT, T1, T2, T3: Tracking stations RICH1-2: Ring Imaging Cherenkov detectors ECAL, HCAL: Calorimeters M1–M5: Muon stations Dipole magnet VELO proton beam proton beam LHCb-1 spectrometer (after this upgrade workshop) LHCb spectrometer (before this upgrade workshop) 1.9 <  < 4.9 or 15 <  < 300 mrad LHCb Upgrade Workshop, Edinburgh

4. LHCb pit (in December 2006) LHCb Upgrade Workshop, Edinburgh

5. pp interactions/crossing n=0 LHCb n=1 Pileup and luminosity • LHC machine, pp collisions at s = 14 TeV: • design luminosity = L = 1034 cm–2s–1, bunch crossing rate = 40 MHz • average non-empty bunch crossing rate = f = 30 MHz (in LHCb) • Pileup: • n = number of inelastic pp interactions occurring in the same bunch crossing • Poisson distribution with mean <n> = Linel/f, with inel = 80 mb • <n> = 25 at 1034 cm–2s–1  not good for B physics • At LHCb: • L tuneable by adjusting final beam focusing • Choose to run at <L> ~ 21032 cm–2s–1(max. 51032 cm–2s–1) • Clean environment: <n> = 0.5 • Less radiation damage • Expected to be available from first physics run • 2 fb–1 of data in 107 s (= nominal year) LHCb Upgrade Workshop, Edinburgh

6. MC studies REMINDER of important requirements for B physics • Flexible and efficient trigger • final states with leptons • fully hadronic final states • Excellent tracking: • Track finding efficiency • Momentum and mass resolution • Vertexing, proper time resolution • Particle identification (p/K///e) • Technical proposal (1998): • Rough detector description • No trigger simulation • No pattern recognition in tracking • Parametrized PID performance • Re-opt. Technical Design Report (2003) • Final detector design • Simulation of L0 and L1 trigger only • First version of full pattern recognition • “DC04” MC datasets (2004–2005): • Detailed material description • First simulation of High-Level Trigger • “DC06” MC datasets (2006–2007): • “Final” geometry and material description • Redesigned High-Level Trigger • “Final” reconstruction algorithms Background estimates: – based on a sample of inclusive bb events equivalent to a few minutes of data taking ! – sometimes can only set limits Today’s numbers: mostly from DC04 MC, at <L> = 21032 cm–2s–1 LHCb Upgrade Workshop, Edinburgh

7. PYTHIA+GEANT full simulation RICH1 VELO TT Magnet RICH2 T1 T2 T3 Expected tracking performance • High multiplicity environment: • In a bb event, ~30 charged particles traverse the whole spectrometer • Track finding: • efficiency > 95% for long tracks from B decays(~ 4% ghosts for pT > 0.5 GeV/c) • KS+– reconstruction 75% efficient for decay in the VELO, lower otherwise • Average B-decay track resolutions: • Impact parameter: ~30 m • Momentum: ~0.4% • Typical B resolutions: • Proper time: ~40 fs (essential for Bs physics) • Mass: 8–18 MeV/c2 * * with J/ mass constraint LHCb Upgrade Workshop, Edinburgh

8.  invariant mass With PID With PID  invariant mass K invariant mass Particle ID performance No PID • Average efficiency: • K id = 88% •  mis-id = 3% • Good K/ separation in 2–100 GeV/c range • Low momentum • kaon tagging • High momentum • clean separation of the different Bd,shh modes • will be best performance ever achieved at a hadron collider LHCb Upgrade Workshop, Edinburgh

9. l- K– Qvtx D B0 Bs SV PV K+ Flavour tagging • Performance assessed on full MC, after trigger and reconstruction • Kaon tags are the most powerful, e.g. opposite K (from bcs) • All tags combined with neural network • Tagging performance depends on how event is triggered ! • will be measured in data using control channels LHCb Upgrade Workshop, Edinburgh

10. Trigger performance & rates • Algorithms and performance: • Level-0 trigger algorithms mature, 1 MHz output rate • High-Level Trigger (HLT) under development • Prototype available within time budget for a limited set of channels • L0*HLT efficiencies: • Determined using detailed MC simulation • Typically 30%–80% for offline-selected signal events, depending on channel • HLT output rates: • Indicative rates (split between streams still to be determined) • Large inclusive streams to be used to control calibration & systematics (trigger, tracking, PID, tagging) LHCb Upgrade Workshop, Edinburgh

11. L = 21032 L = 51032 same-side K opp-side K vertex electron muon combined Physics performance vs L • Rough and quick study: • small DC04 MC samples generated at <L> = 51032 cm–2s–1for a few representative signal channels • backgrounds not investigated yet (but will be possible with DC06 samples) • Preliminary overall conclusion (for L = 2–51032 cm–2s–1): • Significant gain for dimuon channels • yield  L • “Statu quo” for hadronic channels • yield ~ constant • Tagging performance seems ~constant (at least for Bs DsK) LHCb Upgrade Workshop, Edinburgh

12. Integrated luminosity scenario • 2007 (end): • Short pilot run at 450 GeV per beam with full detector installed • Establish running procedures, time and space alignment of the detectors • Integrated luminosity for physics ~ 0 fb–1 • 2008: • LHC reaches design energy • Complete commissioning of detector and trigger at s=14 TeV • Calibration of momentum, energy and particle ID • Start of first physics data taking, assume ~ 0.5 fb–1 • 2009–: • Stable running, assume ~ 2 fb–1/year • Availability of physics results: • with 0.5 fb–1 in ~2009 • with 2 fb–1 in ~2010 • with 10 fb–1 in ~2014 LHCb Upgrade Workshop, Edinburgh

13. Bs +– • Very rare loop decay, sensitive to new physics: • BR ~3.510–9 in SM, can be strongly enhanced in SUSY • Current 90% CL limit from CDF+D0 with 1 fb–1 is ~20 times SM • Main issue is background rejection • with limited MC statistics, indication that main background is b, b • assume background is dominated by b, b • LHCb expected performance: • with 0.5 fb–1: exclude BR values down to SM value • with 2 fb–1: 3 evidence of SM signal • with 10 fb–1: > 5 observation of SM signal LHCb Upgrade Workshop, Edinburgh

14. BR (x10–9) BR (x10–9) 5 observation Expected final CDF+D0 limit SM prediction Uncertainty in bkg prediction 3 evidence SM prediction Integrated luminosity (fb–1) Integrated luminosity (fb–1) Bs +– LHCb limit on BR at 90% CL (only bkg is observed) LHCb sensitivity (signal+bkg is observed) LHCb Upgrade Workshop, Edinburgh

15. sin(2) with B0J/KS • Expected to be one of the first CP measurements: • Demonstrate (already with 0.5 fb–1) that we can keep under control the main ingredients of a CP analysis • in particular tagging extraction from control channels • Sensitivity (from TDR, improved since): • ~ 216k signal events/2 fb–1, B/S ~ 0.8 stat(sin(2)) = 0.02 • With 10 fb–1: • Should be able to reach (sin(2)) ~ 0.010 • to be compared with 0.017 from final BaBar+Belle statistics • Can also push further the search for direct CP violating term  cos(mdt) ACP(t) background subtracted, 2 fb–1 (toy MC) LHCb Upgrade Workshop, Edinburgh

16. Full simulation 0.5 fb–1(signal only, ms = 20 ps – 1) Entries per 0.02 ps Reconstructed proper time [ps – 1] BsDs+ sample and Bsmixing • Measurement of ms: • CDF observed Bs oscillations in 2006: • ms =17.77 ± 0.10 ± 0.07 ps–1 [hep-ex/0609040]compatible with SM • LHCb expectation with 0.5 fb–1: • ~35k Bs Ds-p+ signal events with average t ~ 40 fs and Bbb/S < 0.05 at 90% CL stat(ms) = ± 0.012 ps1, i.e. 0.07% • will be completely dominated by systematics on proper time scale, but at most ((B0))/(B0) = 0.5% • Importance of BsDs+ sample: • Normalization channel for all Bs branching fraction measurements • First absolute measurement from Belle, BR(BsDs+) = (0.68 ±0.22 ±0.16)% [hep-ex/0610003], expect soon ~10% measurement • Control channel for all time-dependent analyses with Bs decays • Measurement of dilution on cos(mst) and sin(mst) terms • Important step towards measurement of other Bs mixing parameters • e.g. mixing phase or CP violation in mixing LHCb Upgrade Workshop, Edinburgh

17. Statistical sensitivities on s for 2 fb–1 Bs mixing phase s with bccs • fs is the strange counterpart of fd=2: • s very small in SM • sSM = –arg(Vts2) =–22 = –0.036 ± 0.003 (CKMfitter) • Could be much larger if New Physics runs in the box • Golden bccs mode is Bs J/: • Angular analysis needed to separate CP-even and CP-odd contributions • Expect ~130k BsJ/() signal events/2fb–1(before tagging), S/Bbb= 8 • Add also pure CP modes such as J/(’), c, DsDs • No angular analysis needed, but smaller statistics • Combined sensitivity after 10 fb–1: • dominated by BsJ/ • systematics (tagging, resolution) need to be tackled • hopefully >3 evidence of non-zero s, even if only SM stat(s) = 0.010 [LHCb-2006-047] LHCb Upgrade Workshop, Edinburgh

18. In April 2006, including CDF’s first measurement of ms After LHCb measurement of s with (s)= ±0.1 (~ 0.2 fb–1) >90% CL >32% CL >5% CL from hep-ph/0604112 After LHCb measurement of s with (s)= ±0.03 (~ 2 fb–1) After LHCb measurement of s with (s)= ±0.1 (~ 0.2 fb–1) Constraints on New Physics in Bs mixing from s measurement 2009 courtesy Z. Ligeti 2009 2010 from hep-ph/0604112 LHCb Upgrade Workshop, Edinburgh

19. bsss hadronic penguin decays • Time-dependent CP analysis of penguin decays to CP eigenstates • B0  KS: • 800 signal events per 2 fb–1, B/S < 2.4 at 90% CL • After 10 fb–1: stat(sin(2eff)) = 0.14 • Similar to a B factory experiment • Bs : • CP violation < 1% in SM (Vts enters both in mixing and decay amplitudes)  significant CP-violating phase NP would be due to New Physics • Angular analysis required • 4k signal events per 2 fb–1 (if BR=1.410–5), 0.4 < B/S < 2.1 at 90%CL • After 10 fb–1: stat(NP) = 0.042 LHCb Upgrade Workshop, Edinburgh

20. AFB(s), theory AFB(s), fast MC, 2 fb–1 s = (m)2 [GeV2] s = (m)2 [GeV2] B0 K*0m+m- • Suppressed loop decay, BR ~1.210–6 • Forward-backward asymmetry AFB(s) in the  rest-frame is sensitive probe of New Physics: • Predicted zero of AFB(s) depends on Wilson coefficients C7eff/C9eff • Other sensitive observables based on transversity angles are accessible (cf A. Golutvin) • Sensitivity (ignoring non-resonant K evts for the time being) • 7.7k signal events/2fb–1, Bbb/S = 0.4 ± 0.1 • After 10 fb–1: zero of AFB(s) located to ±0.28 GeV2 determine C7eff/C9eff with 7% stat error (SM) LHCb Upgrade Workshop, Edinburgh

21. Hiller & Krüger, hep-ph/0310219 Other rare decays • B+ K+l+l– decays • /ee ratio equal to 1 in SM: • New Physics can have O(10%) effect • After 10 fb–1: stat(RK) = 0.043 • Radiative decays: • K*: • ACP < 1% in SM, up to 40% in SUSY • Can measure at <% level • : • No mixing-induced CP asymmetry in SM,up to 50% in SUSY • : • Right-handed component of photon polarization O(10%) in SM • Can get 3 evidence down to 15% (10 fb–1) LHCb Upgrade Workshop, Edinburgh

22. g from Bs DsK • Two tree decays (bc and bu), which interfere via Bs mixing: • can determine s + , hence in a very clean way • similar to 2+ extraction with B0 D*, but with the advantage that the two decay amplitudes are similar (~3) and that their ratio can be extracted from data m = 14 MeV/c2 Bs Ds–+ background (with ~ 15  larger BR) suppressed using PID:  residual contamination only ~ 10% Expect 5400 signal events in 2 fb–1 Bbb/S < 1 at 90% CL (to be updated soon with DC04 MC) LHCb Upgrade Workshop, Edinburgh

23. Both DsK asymmetries 10 fb–1, ms = 20 ps–1) Ds–K+: info on  + ( + s) Ds+K–: info on  – ( + s) g from Bs DsK • Fit the 4 tagged time-dependent rates: • Extract s + , strong phase difference , amplitude ratio • Bs Ds also used in the fitto constrain other parameters (mistag rate, ms, s …) • s(g) ~ 13 with 2 fb–1 • expected to be statistically limited LHCb Upgrade Workshop, Edinburgh

24. Weak phase difference =  Magnitude ratio = rB ~ 0.08 colour-allowed colour-suppressed  from B±  DK± • “ADS+GLW” strategy: • Measure the relative rates of B–  DK–andB+  DK+ decays with neutral D’s observed in final states such as: K–+and K+–, K–+–+and K+–+–, K+K– • These depend on: • Relative magnitude, weak phase and strong phase between B–  D0K– and B–  D0K– • Relative magnitudes (known) and strong phases between D0  K–+ and D0  K–+,and between D0  K–+–+ and D0  K–+–+ • Can solve for all unknowns, including the weak phase : • Use of B±  D*K± under study () = 5–15 with 2 fb–1 LHCb Upgrade Workshop, Edinburgh

25. Weak phase difference =  Magnitude ratio = rB ~ 0.4 colour-suppressed colour-suppressed g from B0 D0K*0 • Treat with same ADS+GLW method • So far used only D decays to K–+, K+–, K+K–and +– final states () = 7–10 with 2 fb–1 LHCb Upgrade Workshop, Edinburgh

26. Sensitivities to  from BDK decays • All channels combined (educated guess): • () = 4.2º with 2 fb–1 • () = 2.4º with 10 fb–1 Signal only, no accept. effect LHCb Upgrade Workshop, Edinburgh

27. 00 +– 2 vs  –+ 70 expts superimposed (2fb–1) average gen Sensitivity to  • SU(2) analysis of B0 +–, ±0, 00: • Main LHCb contribution could be B0 00 • Time-dependent Dalitz plot analysis of B0   +–0 (Snyder & Quinn) • 14k signal events/2fb–1, B/S ~1 Distribution of fit error 15% (< 1%) fake solutions with 2 (10) fb–1 stat() < 10º in 90% of the cases (2 fb–1) LHCb Upgrade Workshop, Edinburgh

28. 10 fb–1 (2014) Impact of LHCb on UT LHCb + LQCD only • LHCb (2 fb–1, 10 fb–1): • LHCb: • (sin(2)) = 0.02, 0.01 • () = 4.2º, 2.4º • () = 10º,4.5º • Lattice QCD (2010, 2014): • 40, 1000 Tflop year • ()/ = 2.5%, 1.5% • Central values: • SM assumed (just for illustration) 2 fb–1 (2010) From V. Vagnoni, CKM workshop, Dec 2006 LHCb Upgrade Workshop, Edinburgh

29.    from B and BsKK 2 fb–1 If perfect U-spin symmetry assumed • Penguin decays, sensitive to New Physics • Measure CP asymmetry in each mode: • Adir and Amix depend on mixing phase, angle , and ratio of penguin to tree amplitudes = d ei • Exploit U-spin symmetry (Fleischer): • Assume d=dKK and =KK • 4 measurements and 3 unknowns(taking mixing phases from other modes) can solve for  • With 2 fb–1: • 36k B, B/S ~ 0.5436k BsKK, B/S < 0.14 • Sensitivity to Adir and Amix~ twice better than current world average stat() = 4 If only 0.8<dKK/d<1.2 assumed 2 fb–1 stat() = 7–10+ fake solution LHCb Upgrade Workshop, Edinburgh

30. Charm physics • Foresee dedicated D* trigger: • Huge sample of D0h+h– decays • Tag D0 or anti-D0 flavor with sign of pion from D*D0 • Performance studies not as detailed as for B physics • just started • Interesting (sensitive to NP) & promising searches/measurements: • Time-dependent D0 mixing with wrong-sign D0K+– decays • Direct CP violation in D0K+K– • ACP  10–3 in SM, up to 1% (~current limit) with New Physics • Expect stat(ACP) ~ O(10–3) with 2 fb–1 • D0+– • BR  10–12 in SM, up to 10–6 (~current limit) with New Physics • Expect to reach down to ~510–8 with 2 fb–1 LHCb Upgrade Workshop, Edinburgh

31.  s b b s   s b Summary • LHCb can chase New Physics in loop decays: • couple superb highly-sensitive bs observables • Bs, Bs mixing phase • expect interesting results with 0.5 fb–1 and 2 fb–1 already • can measure down to SM with 10 fb–1 (in case of no New Physics) • several other exciting windows of opportunity: • Exclusive b  sss Penguin decays (limited, even with 10 fb–1) • Exclusive bsll and bs • B hh Penguins • High statistics charm physics • LHCb can improve significantly on  from tree decays: • use together with other UT observables to test CKM even more But … • this is only MC, performance not demonstrated in real life yet  another 2 years to go ! • while thinking about upgrade, please make sure LHCb-1 will work LHCb Upgrade Workshop, Edinburgh

32. spares LHCb Upgrade Workshop, Edinburgh

33. g from BDK Dalitz analyses • B±  D(KS+–)K±: • D0 and anti-D0 contributions interfere in Dalitz plot • If good online KS reconstruction: 5k signal events in 2 fb–1, B/S < 1 • Assuming signal only and flat acceptance across Dalitz plot: () = 8 with 2 fb–1 • B0  D(KS+–)K*0: • Under study • B±  D(KK)K±: • Four-body “Dalitz” analysis • 1.7 k signal events in 2 fb–1 • Assuming signal only and flat acceptance across Dalitz plot: () = 15 with 2 fb–1 LHCb Upgrade Workshop, Edinburgh

34. Unitarity triangle in 2014 Without LHCb With LHCb at 10 fb–1 From V. Vagnoni, CKM workshop, Dec 2006 LHCb Upgrade Workshop, Edinburgh