Early flavor physics at the LHC

Early flavor physics at the LHC Walter M. Bonivento sezione di Cagliari on behalf of the ATLAS, CMS and LHCb collaborations Thanks to: M.Smizanska (ATLAS), Urs Langenegger (CMS) and LHCb colleagues

The goal of heavy flavor physics is now shifting from Near future of B physics tree level no NP loops:can be affected by NP understanding of the CKM paradigm (SM) search for physics Beyond the Standard Model (BSM) appearing in loops. Future goals of (collider) b physics: 1) precise measurement of γ 2) study loop processes in b s transitions where NP can sneak in a) hadronic penguins b) FCNC decays b sll, b sγ c) mixing related observables: Φ S, Γ s, A CH,indirect CP in A s SL Bs ΦΦ B K*µµ, Bs Φγ Bs J/ψΦ Walter M. Bonivento - INFN Cagliari 2

LHC experiments Experiments being prepared now at LHC ALICE heavy ion and soft-pp experiment ATLAS general purpose pp and heavy ion experiment CMS general purpose pp and heavy ion experiment LHCb dedicated heavy flavour experiment LHCf forward π 0 and γ production MOEDAL magnetic monopole search TOTEM logs and diffraction physics ATLAS, CMS and LHCb are relevant for the flavor physics considered here, and I do not cover production and spectroscopy See JP Revol s talk Walter M. Bonivento - INFN Cagliari 3

LHCb 1.9 < η < 4.9 or 15 < θ < 300 mrad VELO: Vertex Locator (around interaction poin TT, T1, T2, T3: Tracking stations RICH1-2: Ring Imaging Cherenkov detectors ECAL, HCAL: Calorimeters M1 M5: Muon stations Dipole magnet VELO proto n beam Walter M. Bonivento - INFN Cagliari proto n beam 4

Tracking performance High multiplicity environment: In a bb event, ~30 charged particles traverse the whole spectrometer Track finding: VELO efficiency > 95% for long tracks from B decays (~ 4% ghosts for p T > 0.5 GeV/c) RICH1 TT K S π + π reconstruction 75% efficient for decay in the VELO, lower otherwise Average B-decay track resolutions: Impact parameter: ~30 µm Momentum: ~0.4% PYTHIA+GEANT full simulation Magnet RICH2 T1 T2 T3 Walter M. Bonivento - INFN Cagliari 5

Particle ID performance Average efficiency: K id = 88% π mis-id = 3% Good K/π separation in 2 100 GeV/c range Low momentum kaon tagging High momentum clean separation of the different B d,s hh modes will be the best performance ever achieved at a hadron collider 300 - B π + d π + B π - d K + - 250 B s K K - B π + s K - Λ p K 200 b - p π 150 100 Counts 1200 - B π + d π + - B d K π + - 1000 B s K K - B π + s K - Λ b p K 800 - p π 600 400 200 No PID 5100 0 5150 5200 5250 5300 5350 5400 5450 5500 2 MeV/c With PID Λ b ππ invariant mass Counts 250 200 150 100 Λ b With - B π + d π PID + B K π - d + - B s K K - B π + s K - Λ b p K - Λ b p π 50 50 0 5.1 5.15 5.2 5.25 5.3 5.35 5.4 5.45 5.5 2 GeV/c ππ invariant mass 0 5.2 5.25 5.3 5.35 5.4 5.45 5.5 5.55 5.6 2 GeV/c Kπ invariant mass Walter M. Bonivento - INFN Cagliari 6

Schedule (sliding ) April 2008(?): Old commissioning run very low luminosity 10 29 @ s = 900 GeV detector commissioning, alignment and calibration Middle of 2008: Start of run @ s = 14 TeV calibration and trigger commissioning, increasing luminosity toward 10 33 for ATLAS/CMS (?) and ~2 10 32 for LHCb for physics From 2009: Stable physics run @ s = 14 TeV ATLAS and CMS: clear interest to increase luminosities towards 10 34 as quick as possible. B physics will become increasingly difficult. LHCb: collecting data with <10 33 for some years Walter M. Bonivento - INFN Cagliari 7

Luminosity/energy steps considered in this talk Independently of the schedule changes I investigated which physics can be studied in these scenarios: a) s = 900 GeV b) s = 14 TeV i. one hundreth of the nominal one year intergrated luminosity ii. one fourth of the nominal one year integrated luminosity <L>=10 33 for ATLAS and CMS (optimistic?) <L>=2 10 32 for LHCb (should be possible ) Ldt = 2.5 fb -1 each for ATLAS and CMS (if <L> is lower, trigger could be adjusted to have a similar number of b s) Ldt = 0.5 fb -1 for LHCb then everybody can scale the numbers Walter M. Bonivento - INFN Cagliari 8

Cross sections bb cross section large at both s =900 GeV and 14 TeV, but at s = 900 GeV the bb fraction of total inelastic events is ~10 x smaller than at 14 TeV. Process σ @900GeV σ @14TeV Visible σ @14TeV ATLAS+CMS Visible σ @14TeV LHCb total bb cross section 0.025mb 0.5mb 0.1mb 0.23mb total inelastic cross section 40mb 70mb Walter M. Bonivento - INFN Cagliari 9

B triggers at LHC in one slide ATLAS and CMS limited bandwidth for b trigger (5-10% at low L) ATLAS: L1 ( 100kHz) µ pairs or single µ (p T >6GeV) with R.O.I. em+jets info HLT ( 100Hz) with r.o.i. or full scan inside inner detector: jets for hadronic channels, em for channels with e or γ, muons if a second muon is missed by L1; reconstruct intermediate resonances CMS: similar + partial track reco in r.o.i. and B inv mass LHCb: L1( 1MHz) is called L0(!) µ, e,γ and h in HCAL+ pile-up system HLT ( 2kHz) based on alleys with partial reco p T,E T G.V. + hadrons 3.8 electrons 2.8 muon 1.1 2muon 1.3 Event type Exclusive B candidates High mass di-muons Physics B (core program) J/ψ, b J/ψX (unbiased) D* candidates Charm Inclusive b (e.g. b µ) B (data mining) Walter M. Bonivento - INFN Cagliari 10

Triggers for the commissioning run ATLAS 40mb 4kHz interaction rate Data analysis with loose level-1 (LVL1) muon triggers or minimum bias (MB) triggers HLT pass through decay cross section rate ev/day bb µ5x 60nb 60 10-4 Hz 150 bb µ5µ3x 2nb 2 10-4 Hz 5.2 bb J/ψ(µ5µ3)X 0.1nb 0.1 10-4 Hz 0.3 pp J/ψ(µ5µ3)X 1nb 1 10-4 Hz 3 bb Υ(µ5µ3) 1.7nb 1.7 10-4 Hz 4.4 first tests of mass reconstruction possibly large background from muon decays in flight from PV hadrons due to low bb/mb ratio LHCb: only L0 with loose cuts; HLT pass through Walter M. Bonivento - INFN Cagliari 11

Physics with the first 14TeV data Assume 100pb -1 ATLAS+CMS (1/100 of the nominal 1 year luminosity) 20pb -1 LHCb Understanding of detector, trigger, calibration, alignment, material, field, reconstruction, particle ID Beauty production cross sections and bb correlations, production asymmetries covered in Revol s talk J/ψ production both prompt and from beauty: measurement of proper time distribution and reconstruction of exclusive channels Reconstruction of background or control channels for most important measurements Measurement of branching fractions Lifetimes Walter M. Bonivento - INFN Cagliari 12

J/ψ µµ reconstruction Mode LHCb # ev 20pb -1 ATLAS # ev 100pb -1 Total 10 7 10 6 after trigger cuts ATLAS LHCb Walter M. Bonivento - INFN Cagliari 13

Decay Yields of some channels (10-2 y) LHCb # ev ATLAS # ev LHCb B/S ATLAS B/S 20pb -1 100pb -1 B + J/ψK + 17000 0.4 17000 flavor tagging reference for rare dec lifetime B 0 J/ψK S 2280 0.9 1300 0.043 sin(2β), lifetime B 0 J/ψK 0 * 9320 0.155 8700 flavor tagging, lifetime B S J/ψφ `1320 0.12 900 0.15 Φ S Λ b J/ψΛ 260 Λ b lifetime B 0 µµ K 0 * B S D S π 72 1200 0.5 0.4 25 25 <5 new physics B 0 ππ 260 B 0 Kπ 1350 B S KK B S D s µν 370 10000 0.36 hadronic trigger in LHCb!! A SL, tagging Walter M. Bonivento - INFN Cagliari 14

Lifetime sensitivity (10-2 y) Decay σ(τ)/τ stat ATLAS σ(τ)/τ stat+syst W.A. today B + J/ψK + 1.5% 0.4% B 0 J/ψK 0 * 2.2% 0.5% B S J/ψφ 6% 2% Λ b J/ψΛ 8% 5% better with semileptonic Walter M. Bonivento - INFN Cagliari 15

CKM physics with 2008 data (¼y) Some of the very first measurements with 0.5fb -1 will be most probably the reproduction/refinement of the main results from the B factories and the Tevatron: B d mixing phase: β d from B d J/ψK s B s mixing frequency: m s from B s D s π Φ S and Γ S from untagged time-dependent measurements of B s J/ψφ decays (CMS study see afterwards) Γ S from lifetime measurement of decays to pure CP+ or CP- states such as B s K + K - (CP + measures Γ L ) and B s D s µν decay (flavor specific measures <Γ> ) sensitivity under study indirect CP in A s SL with B s D s µν sensitivity under study Bc physics: ex. B c J/ψπ Walter M. Bonivento - INFN Cagliari 16

CKM physics with 2008 data (ii) Other measurements will be a peculiarity of the LHC experiments due to the - high statistics - high energy - good particle ID - good vertexing A couple of golden measurements from Bs physics - Search for Bs µµ decays - Φ s measurement from tagged time-dependent measurements of B s J/ψΦ decays where large, >O(1), BSM contribution not yet excluded Tevatron will run till 2009: CDF and D0, well understood detectors LHC can get b statistics fast Walter M. Bonivento - INFN Cagliari 17

Search for the B s µ + µ - decay 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 µ, b µ assume background is dominated by b µ, b µ (in LHCb we have generated an LHC morning of events) Walter M. Bonivento - INFN Cagliari 18

Search for B s µ + µ - decay Final states with leptons: lepton trigger very effective for ATLAS, CMS and LHCb Flavor tag not necessary, tough background PID: B ππ, Kπ, etc. vertex resolution: b µ-x + b µ+x mass resolution: B µx, etc. + isolation, pt, etc. Bs mass resolutions Bs µ+µ- ATLAS CMS LHCb σ m (MeV/c 2 ) 77 36 18 Walter M. Bonivento - INFN Cagliari 19

Sensitivity ATLAS CMS N signal 2 2 N background 5 4 assuming the SM Br = ~3.5 10-9 upper limit<~5 10-8 (90%CL) BR (x10 9 ) 10 2 LHCb 10 Expected final CDF+D0 limit Uncertainty in bkg prediction SM prediction LHCb: BSM contribution down to the level of SM can be excluded 1 0 0.1 0.2 0.3 0.4 0.5 Integrated luminosity (fb 1 ) Walter M. Bonivento - INFN Cagliari 20

B s mixing phase φ s with b ccs φ s =2β s is the strange counterpart of φ d =2β: φ s very small in SM φ s SM = arg(v ts2 ) = 2λη 2 = 0.036 ± 0.003 (CKMfitter) Could be much larger if New Physics runs in the box Measured with the time-dependent tagged CP asymmetry (CP in the interference between mixing and decay) Golden b ccs mode is B s J/ψφ: Angular analysis needed to separate CP-even and CP-odd contributions Add also pure CP modes such as J/ψη ( ), η c φ, D s D s No angular analysis needed, but smaller statistics B s 0 sb unitarity triangle b t W s t s W b B s 0 Tevatron expect σ(φ S )=0.2 at the end of the run (6fb -1 ) B 0 s b s c c s s } J / ψ }φ Walter M. Bonivento - INFN Cagliari 21

Ingredient 1: Flavor tagging Number of selected signal events = N(sel) Number of useful tagged events for A CP measurement =N(sel)* ε tag Probability of wrong tag = w tag ; Probability of giving a correct tag is D= (1-2 w tag ) dilution A CP =A CP (true)*d l - D Q vtx K A figure of merit for A CP measurement is ε tag *D opposite side: lepton, jet-charge and kaon same side: slow kaon from the fragmentation B PV O.S. S.S. combined K + B s ε tag *D 2 [10-2 ] e µ K Q vtx ATLAS 0.25 0.7 X 3.63 =4.6 CMS Only untaggged analysis so far available LHCb 0.5 0.7 1.6 1.0 2.7 7.1 (NN) Walter M. Bonivento - INFN Cagliari 22

Flavor tagging (ii) - LHCb Mistag rate (w tag ) will be measured in data using several high-statistics control channels: σ(w OS )/w OS ~ 0.3% σ(w SS )/w SS ~ 2% Channel Yield in 0.5 fb 1 B bb /S B + D 0 π + 250k 0.1 B 0 D * - µ + ν 2.2 M 0.3 B + D 0 (*) µ + ν 0.6 M 0.7 Clean B + D 0 π + signal B s D s (*) µ + ν 0.5 M 0.4 B s D s + π - 30 k 0.4 B mass (GeV/c 2 ) Walter M. Bonivento - INFN Cagliari 23

Flavor tagging (iv) Validation channel for OS tagging: B d0 J/ψK S ATLAS LHCb # events 62k 59k B/S 0.043 0.9 σ stat (sin(2β)) 0.035 0.04 to be compared with σ stat (sin(2β))=0.017 from final BaBar+Belle statistics A CP A CP (t) B 0 d 0 0 ( B J / ψks ) N( B J / ψks ) 0 ( B J / ψk ) + N( B J / ψk ) N ( t) = 0 N S b d S c c d s = sin( m t)sin(2β ) d } J / ψ }K 2fb -1 Walter M. Bonivento - INFN Cagliari 24

Ingredient 2: Proper time B s -B s oscillation has to be well resolved: good σ τ needed -good that m s is not too big -resolution function must be well understood measuring lifetimes, oscillation plot with D s π etc. Proper time resolutions ATLAS CMS LHCb σ τ (fs) 83 77 36 N B: worse resolution = more dilution in the CP asymmetries Walter M. Bonivento - INFN Cagliari 25

Proper time issues (LHCb) Proper-time dependence of trigger+selection efficiency: Proper-time resolution dilutes cos( m s t) and sin( m s t) terms, like mistag does knowledge of resolution essential for B s time-dependent physics Obtain information from unbiased data (J/ψ trigger without biasing cuts): Prompt J/ψ µµ, B + J/ψK +, B 0 J/ψK *0 proper time error distributions Resolution modelling τ(fs) Walter M. Bonivento - INFN Cagliari 26

Calibration channel: B s D s- π + B s D s π + : important control channel for time-dependent B s analyses Flavour-specific decay: can use to measure dilution of B s oscillations once mistag known (from other channels) can isolate resolution effect Expect 35k events in 0.5 fb 1 (LHCb only) i with B bb /S < 0.05 at 90% CL Other uses of B s D s π + : Measurement of m s (with 0.5 fb 1 ) σ stat ( m s ) = ± 0.012 ps 1, i.e. 0.07% will be completely dominated by systematics on proper time scale, i.e. σ(τ(b s ))/τ(b s ) end of Tevatron run (6fb -1 ) σ( m s )~0.5%, i.e σ( m s )~0.08ps -1 Normalization channel for all B s branching fraction measurements Entries per 0.02 ps B s0 { Full simulation 0.5 fb 1 (signal only, m s = 20 ps 1 ) Reconstructed proper time [ps 1 ] ~10% absolute measurement of BR(B s D s π + ) expected from Belle s current data b s u d c s } π + }D s Walter M. Bonivento - INFN Cagliari 27

Ingredient 3: mass resolution Good mass and vertex resolutions to reduce background Bs mass resolutions and Background/Signal ratios ATLAS CMS LHCb σ m (MeV/c 2 ) 16.5(*) 14(*) 14(**) B/S 0.25 0.33 0.12 (*)with J/ψ mass constraint (**)without mass constraint Walter M. Bonivento - INFN Cagliari 28

Event yields Event yields from the 2008 run Numbers of reconstructed J/ψφ ATLAS CMS LHCb N sel 23k 27k 33k Full decay topology analysis is needed to determine J/ψφ(CP = +1) / J/ψφ (CP = -1) (L J/ψφ = 0, 2 vs L J/ψφ = 1) Walter M. Bonivento - INFN Cagliari 29

Sensitivity Bs-Bs oscillation phase and decay width difference with 2008 data ATLAS CMS LHCb σ(φ s ) 0.158? 0.044 σ( Γ s )/ Γ s 0.45(*) 0.30(**) 0.15 (*) if Γ s /Γ s ~ 10% (**) from untagged analysis Standard model expectation: φ s = -0.04 LHCb: BSM effect down to the level of SM can be excluded with the 2008 data LHCb: J/ψ η, η c φ, D s+ D s- can be added Walter M. Bonivento - INFN Cagliari 30

Bc physics Example: B c J/ψπ Can help undertsanding heavy quark dynamics Expected resolution (CMS): mass 22Mev/c2 (stat) 14.5Mev (syst) Yield CMS B/S CMS Yield LHCb B/S LHCb σ(τ)/τ stat+syst CMS 300 0.2 3500 0.8 6% Walter M. Bonivento - INFN Cagliari 31