LHCb status and perspectives Yu Guz IHEP Protvino

LHCb: status and perspectives Yu. Guz, IHEP, Protvino on behalf of the LHCb collaboration 1. LHCb detector status 2. Key measurements 3. LHCb upgrade issues 4. Conclusions 1

LHCb: A Large CMS ATLAS ALICE Hadron Collider experiment for Precision Measurements of CP Violation and Rare Decays >700 physicists, 50 institutes, 15 countries 2

LHCb experiment - LHC: √s=14 Te. V, σinelastic~80 mb, σ(bb)~0. 5 mb The bb production is sharply peaked forwardbackward. b b b PT of B-hadron LHCb is a single arm detector 1. 9<|η|<4. 9 B hadron signature: particles with high PT (few Ge. V); displaced vertex (~1 cm from primary vertex) Reconstruction of B decays is based on: • good mass resolution • excellent particle id to reject background • good proper time resolution to resolve B 0 S oscillations b bb angular distribution 100μb 230μb Pythia η of B-hadron 3

The LHCb detector Main components: • silicon strip vertex detector • magnet • tracker stations (inner area: silicon; outer: straw tubes) • two RICH detectors • EM calorimeter with preshower • muon system 4

ready to take data ! The LHCb detector : is installation is complete Muon det Calo’s RICH-2 OT+IT Magnet RICH-1 VELO a beam-gas event 10/09/08 5

LHCb detector performance Detailed Geant 4 simulation • proper time resolution ~ 40 fs Bs Ds(KKπ)K • effective mass resolution ~ 20 Me. V • good K/π separation up to ~60 Ge. V proper time resolution ~ 40 fs ε(K K) : 97% ε(π K) : 5% Eff. mass resolution ~ 20 Me. V 6

LHCb operation at LHC Inelastic pp interactions σ ~ 80 mb Bunch crossing frequency: 40 MHz Design LHC luminosity 1034 cm-2 s-1 Nominal LHCb luminosity: 2∙ 1032 cm-2 s-1 (appropriate focusing of the beam) Expect ≥ 2 fb-1 / year 7

LHCb trigger L 0, HLT and L 0×HLT efficiency L 0 Trigger: hardware, 4 μsec latency High ET (h>3. 5 Ge. V; e, γ>2. 5 Ge. V; μ, μμ>1 Ge. V) Pileup VETO Output rate ~1 MHz High Level Trigger: software, two stages: HLT 1 and HLT 2 HLT 1: confirm L 0 objects, with T, VELO, optionally IP cuts … output ~ 30 k. Hz HLT 2: full reconstruction, exclusive and inclusive candidates Output 2 k. Hz storage, event size ~35 k. B HLT rate Event type Physics 200 Hz Exclusive B decay candidates B (core programme) 600 Hz High mass dimuons J/ , b J/ X (lifetime unbiased) 300 Hz D* candidates Charm (mixing & CPV) 900 Hz Inclusive b (e. g. b ) B (data mining) 8

Flavour tagging e- B 0 opposite PV Same side Bs 0 signal K+ D Qvertex , QJet K- K K – Fragmentation K± accompanying Bs – π± from B** → B(*) π± Effective tagging efficiency: �� εD 2= ε(1 -2ω)2 ε : tagging efficiency ω: wrong tag fraction Opposite side – High Pt leptons – K± from b → c → s – Vertex charge – Jet charge Tag Bd % Bs % Muon 1. 1 1. 5 Electron 0. 4 0. 7 Kaon opp. side 2. 1 2. 3 Jet/ Vertex Charge 1. 0 Same side p/ /K 0. 7 (p ) 3. 5(K) Combined (Neural Net) ~ 5. 1 ~9. 5

LHCb key measurements ► CP-violation ►charm physics ✔ φS ✔Mixing ✔ γ in trees ✔ CP violation ✔ γ in loops ► rare B decays ✔ BS μμ ✔ B K* μμ ►other ✔ τ 3μ (analysis is ongoing) ✔. . . ✔ photon polarization in radiative penguin decays 10

Physics program 2008 (beginning of 2009? ): Lumi ~1031 cm-2 s-1 10 Te. V ~108 sample of minimum bias; L 0+proto-HLT trigger, collect ~ 5 pb -1 Calibration, alignment, minimum bias physics, charmonium production 2009: Lumi 2 1032 cm-2 s-1 14 Te. V L 0 + HLT , collect ~ 0. 5. . 1 fb-1 B Physics: calibration CP (sin 2β, Δms ); key measurements (βs, Bs μμ, …) 2010 -2013: Luminosity 2 -5 1032 cm-2 s-1 collect total of ~10 fb-1 Full physics program Phase I 2013+: Upgrade proposed to run at 2 1033 cm-2 s-1. Collect ~ 100 fb-1 11

CP violation 12

φS measurement Key measurement for 2009 φS is small in SM: φS =-2βS =-2λ 2η ≈ -0. 036 sensitive probe for New Physics: φS = φSSM + φSNP Tevatron results: D 0 2 s= 0. 57 + 0. 24 -0. 30 with 2. 8 fb-1 CDF 2 s = [0. 32, 2. 82] @ 68%CL with 1. 35 fb-1 Measure from time dependent CP asymmetry in b ccs (BS J/ψ φ, BS J/ψ η(η’), BS ηCφ, BS DSDS, …) “golden mode” BS J/ψ φ : high BR (~130 k per 2 fb-1) 13

φS measurement J/ψ φ is not a pure CP eigenstate: angular analysis is necessary to separate CP-odd and CP-even Other b ccs processes (J/ψ η, ηCφ, DSDS) can be added: angular analysis not needed, but smaller statistics The BSM effect in φS can be discovered or excluded with 2008/2009 LHCb data 14

angle γ Measured values 90% CL Fit results 90% CL α 87. 5 +31. 1 -10. 2 90. 7 + 16. 8 - 5. 4 β 21. 5 +2. 0 -1. 9 21. 7 + 2. 0 - 1. 8 γ 76. 8 +52. 7 -50. 4 67. 6 + 5. 3 - 15. 9 Least constrained by direct measurements Key measurement of LHCb Comparison of γ measurement in trees with fitted values, as well as with measurement in loops, is a sensitive probe of New Physics 15

angle γ From tree amplitudes : BS DSK Time dependent CP asymmetry 1 2 From tree amplitudes: B± DK±, B 0 DK* comparison of counting rates: ADS - use doubly Cabibbo-suppressed D 0 decays, e. g. D 0 K+πGLW: Use CP eigenstates of D(*)0 decay, e. g. D 0 K+K- / π+π–, Ksπ0 • Dalitz: Use Dalitz plot analysis of 3 -body D 0 decays, e. g. Ks π+ π- 1 2 3 From penguins : B h h Sensitive to New Physics compare “effective” γ with tree measurements 3 16

γ from BS DSK • interference between tree level decays via mixing • insensitive to New Physics • Measures + 2 s ( s from Bs J/ ) • Bs Ds • 10 times higher branching ratio • suppressed using PID by RICH • used for determination of Δms, ΔΓs and mistag rate Channel Yield 2 fb-1 B/S (90% C. L. ) BS DSK 6. 2 k [0. 08 -0. 4] BS DSp 140 k [0. 08 -0. 3] Sensitivity at 2 fb-1: σ(γ+φs) = 9 o– 12 o Bs→ Ds- + Bs→ Ds-K+ 17

γ from B DK Measure rates of different B DK modes, where D decays into: KŦπ±; CP eigenstates h+h-(h=K, π) (combined ADS+GLW method) Colour favoured Double Cabbibo suppressed Colour suppressed Cabbibo favoured r. D=0. 0611 known to ~1% from elsewhere Nhh/NKπ measurable to ~3% 6 equations, 5 unknowns Decays into KŦ(3π)± can also be included: add 4 equations 2 unknowns 18

γ from B DK Channel Yield (2 fb-1) B/S B → D(hh) K 7. 8 k 1. 8 B → D(Kp) K favoured 56 k 0. 6 B → D(Kp) K suppressed 0. 71 k 2 B → D(K 3 p) K favoured 62 k 0. 7 B → D(K 3 p) K suppressed 0. 8 k 2 σ(γ) = 8 o– 10 o in 2 fb-1 (depending on strong phases) Other methods : B± → DK± with D → Ksππ B± → DK± with D → KKππ (Dalitz analysis) B 0 → DK*0 with D → KK, Kπ, ππ B± → D*K± with D* Dπ, γ; D → KK, Kπ, ππ All methods combined: σ(γ) ~ 5 o from B DK with 2 fb-1 of data 19

γ from B hh time-dependent CP asymmetries in B π+πand BS K+K- : Extract C and S : C(B ππ) = f 1(d, θ, γ) S(B ππ) = f 2(d, θ, γ, φd) C(BS KK) = f 3(d’, θ, γ) S(BS KK) = f 4(d’, θ, γ, φS) deiθ = ratio of penguin and tree amplitudes in B π+πd’eiθ’ = ratio of penguin and tree amplitudes in BS K+K- U-spin symmetry (d s) : d=d’ and θ=θ’ φd and φs known from Bd J/ψ Ks and BS J/ψ φ � 4 observables , 3 unknowns Expected sensitivity: σ(γ) ~ 10 o with 2 fb-1 Channel Yield (2 fb-1) B/S B pp 36 k 0. 5 Bs KK 36 k 0. 15 20

Rare B decays 21

BS μμ Strongly suppressed in SM by helicity: Br= (3. 35 ± 0. 32) x 10 -9 Sensitive to NP models with S or P coupling MSSM: Br ~ tan 6β/MA 4. • Current limits from Tevatron: • CDF BR < 4. 7 10 -8 90 % CL • D 0 BR < 7. 5 10 -8 90 % CL LHCb sensitivity (SM branching ratio) : • 0. 1 fb-1 BR < 10 -8 • 0. 5 fb-1 BR < SM expectation • 2 fb– 1: 3 evidence • 10 fb– 1: 5 observation 22

Bs φγ In SM photon from b sγ is left-handed, from b sγ right-handed φγ final states in B and B do not interfere CP asymmetry in mixing cannot occur Measuring time-dependent CP asymmetry is a probe for NP b (L) + (ms/mb) (R) In SM: Adir 0, Amix sin 2ψ sin 2β Channel Yield B/S AΔ sin 2ψ cos 2β (2 fb-1) tan ψ = |b→sγR| / | b→sγL| Bs→fg 11 k <0. 55 cos 2β 1 Statistical precision after 1 year (2 fb-1) (Adir ) = 0. 11 , (Amix ) = 0. 11 (requires tagging) (AD) = 0. 22 (no tagging required) 23

Afb(s) Bd K*μμ ● Zero crossing point of forward-backward asymmetry AFB in θl angle, as a function of mμμ precisely computed in SM: s 0 SM(C 7, C 9)=4. 39(+0. 38 -0. 35) Ge. V 2 ● sensitive to NP contribution 2 fb-1 s 0 (s 0) = 0. 5 Ge. V 2 s = (m )2 [Ge. V 2] (resonances excluded) Channel Yield (2 fb-1) BG (2 fb-1) Bs→K* + – 7200+-2200 (BR) 1770+-310 B factories total ~ 1000 events by now 24

Charm & tau 25

Dedicated D* trigger 2 charged tracks from a detached vertex with -700<(mππ-m. D 0)< 50 Me. V; + another charged track matching the hypothesis of D* D 0π decay (vertex, Δm) D 0 s are flavor tagged with π from D* decay Two sources of D 0 s in LHCb: q from B decays Ø favoured by LHCb triggers q prompt production in primary interaction Estimated annual yields (per 2 fb-1) from B decays: D 0 K-π+ (right sign) 12. 4 M D 0 K+π- (wrong sign) 46. 5 k D 0 K+K 1. 6 M D 0 π+π0. 5 M Similar amounts expected from prompt production 26

LHCb prospects for Charm physics studies D 0 mixing q Time-dependent D 0 mixing with wrongsign D 0 K+π- decays § Strong phase δ between DCS and CF amplitudes: (x, y) (x’, y’) q Lifetime ratio: mean lifetime (D K- π+) and CP even decay D K+K-(π+π-) The mixing has been recently observed (Belle, Ba. Bar, CDF) y. CP=y in absence of CP violation (φ=0) 0. 26 LHCb sensitivities with 10 fb-1: σstat(x’ 2) ~ 6. 4·10 -5, σstat(y’) ~ 8. 7·10 -4; σstat(y. CP)~ 4. 9·10 -4 x = 0. 89± 0. 27 % 0. 17 y = 0. 75± 0. 18 % 27

LHCb prospects for Charm physics studies q 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, Ba. Bar, CDF): ACP = -0. 16 ± 0. 23 LHCb sensitivity with 10 fb-1: σstat(ACP) ~ 4. 8·10 -4 28

τ 3μ (preliminary) Present upper limit: Br(τ 3μ) < 3. 2·10 -8 @90%CL (Belle) Br(τ 3μ) < 5. 3·10 -8 @90%CL (Ba. Bar) Preliminary analysis shows that at 2 fb-1 LHCb can obtain upper limit of ~6·10 -8 The result is not final: background estimate may change, event selection refined. background τ 3μ σ=8. 6 Me. V 29

Upgrade issues 30

10 fb-1 will be collected by 2013 Sensitivities for 100 fb-1 • φS measured to 0. 023 • γ to 2 - 5 o • BS μμ observed at 5σ level • many more excellent physics results next step – collect 100 fb-1 Probe/measure NP at % level • have to work at > 1033 cm-2 s-1 • upgrade is necessary Also studying Lepton Flavour Violation in 31

LHCb at higher luminosity • The L 0 hadron trigger saturates the bandwidth (1 MHz) at 2·1032 cm-2 s-1 • typical L 0 efficiency for purely hadronic final states ~ 50% will drop with luminosity • apart from the trigger, the LHCb performance does not deteriorate significantly up to 1033 cm-2 s-1 • A 40 MHz readout of all the detectors is the only way to achieve 1033. Introduce first level trigger on detached vertex on a CPU farm LHC schedule • Phase 1: IR upgrade. Install new triplets β*=0. 25 m in IP 1 and 5. Requires 8 month shutdown in 2012 -2013 • Phase 2: inner detectors of ATLAS and CMS need to be replaced. 18 month shutdown in ~2017 32

LHCb upgrade strategy the main effort is to upgrade by 2014 all Frontend Electronics to 40 MHz readout. • perform also necessary upgrade of subdetectors • replace readout chips in the vertex detector (VELO) • RICHs: the readout chips are encapsulated inside photodetectors replace all photodetectors ! • Tracking system: replace all Si sensors, as readout chips are bonded on hybrids • run from 2014 at 1033 cm-2 s-1 until the Phase 2 shutdown. Reach 20 fb-1. in 2017 upgrade the subdetectors for >2·1033 cm-2 s-1 • fully rebuild vertex detector (pixels or 3 D) • rebuild Outer Tracker, replace central part of EM calorimeter, … • run at highest possible luminosity for 5 years. 33

Conclusions • The LHCb detector at LHC is commissioned and ready to take data • key measurements with 2009 data: • φS: precision ~0. 023 • BS μμ : sensitivity ~ SM expectations • Full physics program in 2010 -2013 at 10 fb-1: • angle γ (precision of ~5 o with 2 fb-1 ) • search for New Physics in photon polarization in b sγ • precision measurement of AFB in B K*μμ • Charm physics: D 0 mixing, direct CP violation in D 0 KK(ππ) • and much more… • 2013+: upgrade of the detector, aiming to reach 100 fb -1 at operating luminosity of 1033 cm-2 s-1 (and >2·1033 cm-2 s-1 in 2017+) 34

Backup 35

τ 3μ (preliminary) τ 3μ Event selection cuts per track: ❚ PT > 0. 4 Ge. V ❚ IP( )/ IP > 3. 0 ❚ d. LL > -3 Main source of τ: DS decays cuts per 3 vertex: ❚ 2 < 9 ❚ |V 3 -Vprim|/ > 3 ❚ Z 3 -Zprim > 0 cm ❚ IP( )/ IP < 3 Background rejection: 4. 9·10 -9 2 fb-1: 5. 6·1010 τ produced Per 2 fb-1 ~2200 bg evts expected Signal selection efficiency: 2. 3% upper limit 78. 5 ev Corresponds to Br limit 6. 1 ·10 -8 36