The LHCb Experiment at the LHC Status and Physics plans

The LHCb Experiment at the LHC Status and Physics plans Elie Aslanides CPPM, Aix Marseille Université et CNRS/IN2P3, Marseille, France On behalf of the LHCb Collaboration

Introduction The LHCb detector New Physics strategy Priorities for 2010 Latest news highlights Conclusions 2

The experiments at LEP, SLC, the Tevatron and B factories confirm the SM predictions. Physics in the quark sector is well described by the CKM mechanism. Accuracy of the UT sides is limited by theory: V ub, Accuracy of angles is limited by the experiment: σ(α) ~ 5, σ(β) ~ 1, σ(γ) ~ 20 The phase of the mixing induced CPV, φ s, in the B s J/ψφ decay (-2β s in SM) is not yet measured, but a hint for a large value came from the Tevatron! 3

The ambition of the LHC experiments Search for the SM Higgs boson in the 115 GeV to 1 TeV mass region Search for New Physics (NP) beyond the Standard Model direct search for New particles up to the TeV scale ATLAS/CMS indirect effects, induced by NP at higher mass scales mostly LHCb? Assuming NP has flavour structure and specific couplings, CPV and Rare decays, mediated by loop (box and penguin) diagrams, are sensitive to the presence of new particles.? At the LHC direct and indirect approaches are complementary! 4

High precision study of CP Violation and rare B-decays Extension of the measurements at the B-factories and the Tevatron Search for NP in a complementary way to ATLAS and CMS 800 participants 54 institutes 15 countries 5

Introduction The LHCb detector New Physics strategy Priorities for 2010 Latest news highlights Conclusions 6

Beauty production at the LHC At LHC energies strongly correlated b-bbar production! ATLAS/CMS central detectors, η < 2.5 B physics using high-p T µ triggers, mostly with modes involving di-muons LHCb designed to maximize the B acceptance forward spectrometer 1.9 < η < 4.9 relies on lower p T triggers efficient also for purely hadronic B decays bb produc?on cross sec?on at s=14 TeV 100 µb 230 µb Pythia 7

The LHCb spectrometer VErtex LOcator 21 stations (r,φ) Si strips Dipole magnet Tracking system Calorimeters Muon system 250 mrad p p 10 mrad RICH detectors 8

LHCb working luminosity At s = 14 TeV σ bb ~ 500 µb but σ bb /σ tot ~ 5 10-3 interesting B decays have low b.r. ~10-5 Adopted luminosity L ~ 2 10 32 cm 2 s 1 pp interactions/bunch crossing (n = 0.5) Expected integrated luminosities L int ~ 2 fb 1 / year (10 7 s) ~ 10 12 bb pairs per year L int ~ 10 fb 1 in 5 years At the start up phase (2010) at s = 7 TeV? Expected L int : 0.2-0.3 fb 1 9

Experimental requirements for LHCb Efficient and flexible Trigger High quality Event Reconstruction particle identification hadrons,µ s and e s, as well as γ s, π 0 s excellent tracking and vertexing good p, mass, and τ resolutions Powerful Online processing and fast readout 10

The LHCb trigger 40 MHz Pileup system Calorimeters Muons Level 0 p T µ, e, h, γ Custom Electronics 4 µs latency 1 MHz Full detector information HLT (I) L0 confirmation; associates p T and IP (II)Reconstruction of relevant topologies Farm of O(2000) multi-core processors Flexible/adaptable to the Physics needs. storage 2 khz Event size ~35kB 11

Detector Performance: tracking Expected tracking performance Efficiency > 95% for tracks from B decays crossing entire detector δp/p: 0.3% - 0.5% (depending on momentum) Proper time resolution: ~ 40 fs B mass resolution: 15-20 MeV/c 2 Bs Ds(KKπ)K Proper time resolution ~ 40 fs Mass resolution ~ 20 MeV 12

Detector performance: particle ID RICH1 Aerogel (2-10 GeV), Fluorobutane C 4 F 10 (10-60 GeV) RICH2 CF 4 (15-100 GeV) Good π K separation in the range 2-100 GeV/c At low momentum Tagging Kaons At high momentum Separation of the hadronic decay modes B d,s hh π-k separation K identification 90% π mis-identification 3% no PID with PID ππ invariant mass with PID ππ invariant mass Kπ invariant mass 13

Introduction The LHCb detector New Physics strategy Priorities for 2010 Latest news highlights Conclusions 14

New Physics search strategy Phases of New Physics CPV processes are the only measurements sensitive to them measure β, φ s & γ Masses and magnitude of the couplings of new particles Look for the very rare loop (helicity suppressed) decay: B s µµ with large sensitivity to SUSY with extended H sector, e.g. CMSSM and large tan 2 β. Helicity structure of the couplings (testing the V-A structure of the W.I.) Exploit the correlation between γ polarization and b flavour to look for R-handed currents b γ (L) + (m s /m b ) γ(r)? B s and B s decays into φγ should not interfere; A CP =0 Significant A CP 0 would indicate the presence of R- handed current in the penguin loop! 15

The phase of the mixing induced CPV, φ s φ s is the B s meson counterpart of 2β (penguin contribution 10-3 ). B s J/ψφ The SM uncertainty is very small: -2β s = - 0.0368±0.0017 (CKM fitter 2007) B s φ s is not measured yet (although indication of large value from the Tevatron) CDF+D0 (2009) result (2.8 fb 1 each) φ s [ 1.18, 0.54] [ 2.60, 1.94] at 68% CL LHCb with 2 fb -1 will yield ~117k B s J/ψφ evts σ(φ s ) ~ 0.03 (of order 2β s ) LHCb with 10 fb -1 σ(φ s ) ~ 0.01 Will be able to measure φ SM s within 3σ or any higher φ s (due to NP) with greater accuracy! φ s sensitivity LHCb 10 TeV If the central value of the Tevatron hint is true, then LHCb will observe New Physics in 2010, with 200 pb -1 and σ(φ s ) ~ 0.12.

CP Violation measurements: UT angles UT geometry implies that the main constraint on NP comes from the comparison of the angles and their opposite sides: angle β vs V ub / V cb largely limited by theory (~10% precision in V ub ) angle γ vs Δm d /Δm s limited by the experiment (γ is poorly measured ± 20 ) Direct Indirect measurement Indirectly, γ is determined to be γ = (68 ± 5)º from box processes. LHCb will measure γ directly in tree decays using the global fit to the rates of B D 0 K,D 0 K* decays and time-dependent measurements with B s D s K and B 0 Dπ decays. Expected σ(γ trees ) 4 with 2 fb -1

CPV measurements: penguins trees δ2β(np) = 2β(B d φk s ) - 2β(B d J/ψK s ) δφ s (NP) φ s (B s φφ) - φ s (B s J/ψφ) Thanks to B-factories measurements δ2β(np) ~ - 0.23 ± 0.18 rad σ(δφ s (NP)) not yet measured LHCb sensitivity with 2 fb -1 ~ 0.11 rad (stat. limited)

A very rare decay in SM with well predicted branching ratio BR (B s µµ) = (3.6±0.4) 10-9 Buras Oct. 09 +NP? sensitive to NP, in particular, strongly enhanced in SUSY with scalar Higgs exchange : BR tan 6 β / M 4 A +NP? Current best limit from CDF: < 36 10-9 (90% CL) Expected CDF +D0 (8 fb -1 each): < 20 10-9 (90% CL) ~5 times higher than the SM prediction! Main issues for LHCb: the background rejection. MSSM background is dominated by B µ + X, B µ - X decays various control channels used to minimize dependence on MC B + J/ψ (µ + µ - ) K +, B J/ψ (µ + µ - ) K * (K + π - ), B (s) h + h - 19

BR(B s 0 μ + μ ) (x10 9 ) 90% C.L. exclusion limits at 8 TeV CM LHCb expected performance for the branching ratio of B s µ + µ In 2010 physics start up with ~ 0.2 fb -1 Should improve and take over the expected Tevatron final sensitivity. BR(B s 0 μ + μ ) (x10 9 ) 3σ observa?on evidence * 5σ observa?on Observa?on poten?al at 14 TeV CM From 2011 and on ~3 fb -1 for 3σ evidence ~10 fb -1 for 5σ observation of the SM value 20

The suppressed loop decay B K*µµ Forward-backward asymmetry A FB (s) of the θ l distribu)on in the µµ rest-frame is a sensitive probe of New Physics its zero crossing of A FB has small theoretical uncertainty depends on the ratio of the Wilson coeffs C eff 7 /C eff 9 Theory (illustration) A FB (s) s = (m µµ ) 2 [GeV 2 ] 21

LHCb sensitivity to A FB LHCb expects 6.4k signal events /2fb 1, with B/S ~ 0.25 (at B factories ~ 0.35k/1 ab 1 ) At 14 TeV, with 2 fb -1 The zero crossing of A FB can be measured with σ(s0) ~ 0.5 GeV 2. With higher luminosities A full analysis of the 3 angular distributions θ l, φ, θ K becomes possible. N.B. Angular acceptance and backgrounds need to be understood, using control channels e.g. B 0 J/ψK* 0. With ~200 pb -1 in 2010, LHCB will accumulate several 100k, the world s largest sample, of K*µµ events. Already in 2010 LHCb could give a hint on the tendency of the A FB! A FB (s) LHCb, 2 fb 1 (assuming SM) BABAR 2008 (PRD 79, 031102) Belle 2009, PRL 103, 171801 s = m µµ 2 (GeV 2 ) s 0 SM = (4.4 ± 0.3) GeV 2 22

Measurement of the photon polarization in B s φγ ( ) &e '" s t ( cosh ((" s t /2) ' A ( sinh ((" s t /2) + Ccos ((m s t) 'Ssin((m s t) ) ( ) &e '" s t ( cosh ((" s t /2) ' A ( sinh ((" s t /2) ' Ccos ((m s t) + Ssin ((m s t) ) " B s 0 (t) # $% " B s 0 (t) # $% The decay final state φγ is not a CP eigenstate because the photon is polarized! In the SM [Atwood et al, PRL 79 (1997) 185, PRD 71 (2005) 076003] C < 1% (no direct CPV), S = sin(2ψ)sinφ, A Δ = sin(2ψ)cosφ φ ~ 0 (cancellation of mixing and decay phases) tanψ is the fraction of wrong polarization tan" = A(B 0 s # $% right ) A(B 0 s # $% left ) An untagged time-dependent analysis in B s φγ can yield tanψ. Due to the V-A coupling of the W, photons in b sγ are left handed. The wrong polarization fraction is small tanψ = A R /A L ~ 0.04, mainly due to m s /m b, but can be enhanced up to 0.4 in NP models! 23

Measurement of the photon polarization (II) BaBar & BELLE used CPV analysis in B K*(K 0 π 0 )γ decay σ ( A (B f CP γ R ) / A (B f CP γ L )) ~ 0.16 (HFAG 2009) In LHCb using the B s φγ decay measurements time-dependent analysis of 11k signal events for 2 fb -1, (B/S < 0.9; m resolution ~ 100 MeV/c 2 ; τ resolution ~ 90 fs; ε vs τ to be controlled?) σ stat (A R / A L ) ~ 0.11 In LHCb we will also study the B d K * e + e - decay The virtual photons contribution is dominating at low q 2 < (1 GeV) 2. Expected with 2 fb -1 : ~ 200 250 events with B/S ~ 1 sensitivity: σ stat (A R /A L ) 0.1 24

The LHCb key measurements At 14 TeV with a luminosity of <L> 2 10 32 cm -2 s -1 and 2 fb -1 /y, (10 7 s/year) LHCb should reach, in 5 y, unprecedented precisions in both B d and B s and attempt the search for CPV in the charm sector! σ( 2 fb -1 ) φ s ~0.03 γ (trees) ~4.5 γ (loops) ~7 Br(B s µ + µ - ) 3σ measurement (SM) B d K *0 µ + µ - σ(s 0 )=0.5 GeV 2 γ polarization σ stat (A R /A L ) = 0.1 (in B S φγ) in radiative σ stat (A R /A L ) = 0.1 (in B d Κ*e + e - ) Penguin decays 25

Introduction The LHCb detector New Physics strategy Priorities for 2010 Latest news highlights Conclusions 26

The first measurements in 2010 Calibration and minimum bias physics: 10 8 events K s ππ and Λ pπ (95% purities achievable using kinematical & vertex cuts). PID studies and momentum calibration (600k ev/pb -1 ) J/ψ trigger on single µ with p t cut. J/ψ physics and production cross-sections (~ 1-5 pb -1 ) differential cross-section for prompt J/ψ; and bb production cross-section (secondary J/ψ). Commissioning the analysis in the hadronic modes Study in detail the channels D hh. Accumulate samples of B D(Kπ)π. Charm physics: 20 pb -1 and upwards (Exciting possibilities even with low L) Use flavour tagged D 0 KK events to measure the lifetime asymmetry for CP ±1 eigenstates y CP = τ(d 0 Kπ) / τ(d 0 KK) 1 with a sensitivity of σ 1 x 10 3 LHCb could overtake the present BELLE (0.11M evts) statistics with only a few pb -1! 27

New Physics discovery potential in 2010 B s µµ With a data sample of ~200 pb -1 LHCb should be able to improve the Tevatron sensitivity for the BR (B s µµ) and the phase ϕ s. LHCb 90% C.L. exclusion limits at 8 TeV φ s sensitivity φ s LHCb 10 TeV Present central value from Tevatron would be confirmed at the 5σ level. 28

Introduction The LHCb detector New Physics strategy Priorities for 2010 Latest news highlights Conclusions 29

The LHCb detector was ready to take data since summer 2008. 30

On September 10, 2008 Beam 1 was circulated during few hours (in the correct direction for LHCb) Two types of events were observed: beam-gas events and splash events hitting the collimator. LHCb made a very successful start! Beam gas OT Calo Muon Beam splash 31

Monday November 23, 17:45 LHCb observed its first p-p collisions at 450 + 450 GeV 32

LHCb 23 Nov 2009 Olivier Callot 26 Nov 2009 33

Events have nice vertices (extrapolating OT tracks) LHCb 23 Nov 2009 Olivier Callot 26 Nov 2009 34

Zoom on the VErtex LOcator area VELO detector was OFF. Only the RF foil envelope is drawn. 50 cm LHCb 23 Nov 2009 Olivier Callot 26 Nov 2009 35

Vertices are clustered as measured with OT tracks, 7 to 9 m downstream. Beam gas only LHCb PRELIMINARY Beam gas AND collisions Mean: 8 ± 17 mm σ : 101 ± 17 mm LHCb 23 Nov 2009 Olivier Callot 26 Nov 2009 36

Collisions at the injection energy have been again observed in LHCb on Sunday, December 6 from 02:01 on The full detector including the VELO in around 23:40. 37

Muon tracks with B field ON LHCb 6 Dec 2009 Burkhard Scnmidt 8 Dec 2009 38

Event with the VELO fully powered up and partially closed! LHCb 6 Dec 2009 Burkhard Schmidt 8 Dec 2009 39

Latest highlights from LHCb December 14, 2009 Andrey Golutvin 40

Proton-proton interaction vertices as seen by the VELO (VELO was 15 mm away from its nominal position, 8 mm from the beam) A-side X, mm X, mm C-side Y, mm Y, mm Z, mm Z, mm December 14, 2009 Andrey Golutvin 41

VELO + Outer Tracker + Silicon Tracker see K S and Λ Full tracking with VELO! Tracking without VELO Ks Ks Λ Λ December 14, 2009 Andrey Golutvin 42

Ring Imaging CHerenkov s identified Kaons LHCb data (preliminary) RICH 1 Kaon ring Orange points : photon hits Continuous circles : expected distribution for each particle hypothesis (proton below threshold) LHCb data (preliminary) RICH 2 Kaon ring December 14, 2009 Andrey Golutvin 43

Electromagnetic CALorimeter reconstructs the π 0 signal (first data, 23 November 2009, No B-field) LHCb data (preliminary) Now π 0 peak can be routinely monitored on-line! LHCb data (preliminary) M γγ (MeV/c 2 ) <m> = (133 ± 3) MeV/c 2 σ = (11 ± 4) MeV/c 2 M γγ (MeV/c 2 ) December 14, 2009 Andrey Golutvin 44

During the last week end the LHC was running almost routinely long periods of stable beams at 450 GeV good beam lifetimes beam intensities of up to 7 x 10^10 protons per beam All experiments recorded around 1M events at 450+450 GeV. The machine operators performed more tests at the higher energy of 1.18 TeV per beam the experiments saw about 50 000 collisions each at 2.36 TeV LHCb registered its first collisions at 2.36 TeV on Monday, December 14 at 04:00! 45

Introduction The LHCb detector New Physics strategy Priorities for 2010 Latest news highlights Conclusions 46

Conclusions LHCb is fully operational and taking data! collected a large sample (> 1 million) of Minimum Bias events. First data are used to understand the detector calibration and trigger optimization as well as to look for first exploration of low p T physics at LHC energies some high class measurements in the charm sector. In 2010 (with 200 pb -1 ) LHCb will reach sensitivity to New Physics overtake the Tevatron in some golden channels in the beauty sector. With ~ 10 fb -1 LHCb has an excellent discovery potential of New Physics and will complement the ATLAS/CMS physics programme. 47

Extras backups 48

180 160 140 120 100 Charm physics: the measurement of y CP Use flavour tagged D 0 KK events to measure the lifetime asymmetry for CP ±1 eigenstates KK M 0 D Lifetime ratio t / t 2 / ndf Kpi KK, 30 bins D 0 KK y CP = τ(d 0 Kπ) / τ(d 0 KK) 1. LHCb expects 42000 reconstructed D 0 KK evts/pb -1 passing L0 and HLT1! Could overtake the present BELLE (0.11 M evts) statistics with only 2.6 pb -1 and collect up to 8.4 10 6 tagged D 0 KK events in 2010 (200 pb -1 ). Expected precision on y CP in 2010 is σ stat (y CP ) 1. 10 3 reconstructed in 10 9 min. bias (.02 pb -1 ) 11.4 11.2 11 10.8 10.6 N(D 0 Kπ) /N(D 0 KK) χ 24.65 / 28 Constant 9.931 ± 0.016 Slop 0.01559 ± 0.00271 Toy MC 80 10.4 60 40 20 0 1780 1800 1820 1840 1860 1880 1900 1920 1940 1960 Mass / MeV -0.5 0 0.5 1 1.5 2 2.5 ps 49 10.2 10 9.8 9.6

LHCb Trigger Level -0 40 MHz L0 e, γ L0 had L0 µ Trigger is crucial as σ bb /σ inel < 1% B decays of interest typically have b.r. < 10-5 hardware Level-0 trigger 1 MHz search for high- p T µ, e, γ and hadron candidates High-Level Trigger HLT1 30 khz HLT2 2 khz ECAL Alley Hadr. Alley Global reconstruction Inclusive selections µ, µ+track, µµ, topological, charm, ϕ Muon Alley & Exclusive selections Storage: Event size ~35kB software High Level Trigger (HLT) Farm of O(2000) multi-core processors HLT1: confirms L0 candidates with more information associates IP and p T HLT2: B reconstruction + selections for storage Electromagnetic 70 % Hadronic 50 % Muon 90 % ε(l0) ε(hlt1) ε(hlt2) > ~80 % > ~90 % 50

Trigger used for the first beams and collisions Level 0 : Minimum bias Hadron: (E T > 500 MeV in the HCAL) AND (MULT(SPD)> 2 hits) OR Muon: muons p T > 500MeV/c HLT Pass all events... Offline reconstruction To start automatically on the grid when a file was received. Very small files LHCb 23 Nov 2009 Olivier Callot 26 Nov 2009 51

Commissioning of the LHCb detector First time synchronization and space alignment was performed using cosmics and LHC Beam 2 dumped on the injection line beam stopper (TED); The use of cosmics in LHCb (a forward spectrometer) is a real challenge, limited to the commissioning of the large sub-detectors (OT, Calos, Muon stations) and Trigger. Using the few Hz Trigger on horizontal cosmic tracks Muon & CALO were synchronized to a few ns. OT was aligned to ~ 1 mm. The L0 trigger commissioned. 52

Tested with TED events ~300 m TI8 SPS Large multiplicity, ~2/cm 2 useful for small precise detectors Several periods in 2008 and 2009 Very useful to get a first time and position alignment LHCb 23 Nov 2009 Olivier Callot 26 Nov 2009 53

VErtex LOcator alignment TED tracks perfectly suited for VELO alignment : they cross detector almost parallel to z-axis 21 stations of Si wafer pairs with r and φ strip readout VErtex LOcator tracks, August 22, 2008 φ strips resolution in µ R strips December 15 20, 2009 Resolution estimated from VELO hit residuals agrees well with expectations Elie Aslanides, Miami 2009 54

LHCb Physics programme Mainly on the search for effects induced by New Physics in CPV and Rare decays through FCNC processes mediated by loop (box and penguin) diagrams.?? Ф Ф s Ф s SM Effects sensitive to the phases, the masses, couplings and spins of New Particles 55

Advantages of indirect approaches Can in principle access higher scales and see effect earlier: 3rd quark family inferred by Kobayashi and Maskawa (1973) to explain small CPV measured in Kaon mixing (1964), but directly observed in 1977 (b) and 1995 (t) Neutral currents (ν+n ν+n) discovered in 1973, but real Z discovered in 1983 Can in principle 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 it is important to measure this structure, including new phases.?? B s φφ decay: Penguin diagram Standard Model New Physics Δm s φ s Δm s SM V ts2, φ s SM = arg(v ts2 ) = 2β s???? B s B s oscillations: Box diagram 56