Early physics with the LHCb detector

Transcription

1 XXVIII PHYSICS IN COLLISION - Perugia, Italy, June, 25-28, 2008 Early physics with the LHCb detector Dirk Wiedner CERN for the LHCb collaboration 27 June 2008 Dirk Wiedner at PIC2008 Perugia 1

2 Outline LHCb detector First days of data taking Beauty cross section Summary and Outlook 27 June 2008 Dirk Wiedner at PIC2008 Perugia 2

3 s = 14 TeV LHCb: L=2-5 x cm -2 s -1 bb = 500 b inel / bb = 160 => 1 year = 2 fb -1 LHC b b LHCb ATLAS b b CERN CMS ALICE A Large Hadron Collider Beauty Experiment for Precision Measurements of CP-Violation and Rare Decays 27 June 2008 Dirk Wiedner at PIC2008 Perugia 3

4 The LHCb Detector Beryllium beam pipe 27 June 2008 Dirk Wiedner at PIC2008 Perugia 4

5 The LHCb Detector Muon det Calo s RICH-2 Magnet OT RICH-1 VELO Beryllium beam pipe 27 June 2008 Dirk Wiedner at PIC2008 Perugia 5

6 The LHCb Detector Muon det Muon det Calo s RICH-2 OT Magnet Calo s RICH-2 OT+IT Magnet RICH-1 RICH-1 VELO VELO Beryllium beam pipe Installation of major structures is complete 27 June 2008 Dirk Wiedner at PIC2008 Perugia 6

7 A walk through the LHCb spectrometer 27 June 2008 Dirk Wiedner at PIC2008 Perugia 7

8 B-Vertex Measurement Vertex Locator (Velo) Silicon strip detector 8 mm from beam with ~ 5 m hit resolution 27 June 2008 Dirk Wiedner at PIC2008 Perugia 8 30 m IP resolution

9 B-Vertex Measurement Example: Bs Ds K Primary vertex 47 m B s 144 m D s d 1 cm K 440 m Decay time resolution = 40 fs K K ) ~40 fs Vertex Locator (Velo) Silicon strip detector 8 mm from beam with ~ 5 m hit resolution 27 June 2008 Dirk Wiedner at PIC2008 Perugia 9 30 m IP resolution Vertexing: Impact parameter trigger Decay distance (time) measurement

10 Momentum and Mass measurement Momentum meas.: Mass resolution for background suppression 27 June 2008 Dirk Wiedner at PIC2008 Perugia 10

11 Momentum and Mass measurement Momentum meas.: Mass resolution for background suppression 27 June 2008 Dirk Wiedner at PIC2008 Perugia 11

12 Momentum and Mass measurement Momentum meas.: Mass resolution for background suppression Mass resolution ~14 MeV Bs μμ Bs KK B mass resolution MeV/c 2 27 June 2008 Dirk Wiedner at PIC2008 Perugia 12 12

13 Particle Identification RICH: K/ identification using Cherenkov light emission angle Cherenkov rings RICH1 RICH1: 5 cm aerogel n= m 3 C 4 F 10 n= RICH2: 100 m 3 CF 4 n= June 2008 Dirk Wiedner at PIC2008 Perugia 13

14 Particle Identification RICH: K/ identification using Cherenkov light emission angle Cherenkov rings RICH1 RICH1: 5 cm aerogel n= m 3 C 4 F 10 n= RICH2: 100 m 3 CF 4 n= June 2008 Dirk Wiedner at PIC2008 Perugia 14

15 Particle Identification RICH: K/ identification; eg. distinguish D s and D s K events. Cerenkov light emission angle Bs Ds K B s D s,k K K K K : ± 0.06% K : 5.15 ± 0.02% Primary vertex b tag RICH1: 5 cm aerogel n= m 3 C 4 F 10 n= RICH2: 100 m 3 CF 4 n= June 2008 Dirk Wiedner at PIC2008 Perugia 15

16 LHCb calorimeters e h Calorimeter system : Detection of electrons, π 0, γ Primary vertex 27 June 2008 Dirk Wiedner at PIC2008 Perugia 16 Level 0 trigger: high E T electron and hadron, photon B s b tag D s K K K

17 LHCb calorimeters e h Calorimeter system : Detection of electrons, π 0, γ Primary vertex 27 June 2008 Dirk Wiedner at PIC2008 Perugia 17 Level 0 trigger: high E T electron and hadron, photon B s b tag D s K K K

18 LHCb muon detection Muon system: Level 0 trigger: High Pt muons Muon ID 27 June 2008 Dirk Wiedner at PIC2008 Perugia 18

19 LHCb muon detection Muon system: Level 0 trigger: High Pt muons Muon ID 27 June 2008 Dirk Wiedner at PIC2008 Perugia 19

20 LHCb trigger 40 MHz 1 MHz Detector L0: high p T (, e,, h) [hardware, 4 s] HLT: L0 confirmation with improved detector resolution, followed by full event reconstruction L0, HLT and L0 HLT efficiency 2 khz Storage (event size ~ 50 kb) HLT rate Event type 200 Hz Exclusive B candidates 600 Hz High mass dimuons Physics B (core program) J/, b J/ X (unbiased) 300 Hz D* candidates Charm (mixing & CPV) 900 Hz Inclusive b (e.g. b ) B (data mining) 27 June 2008 Dirk Wiedner at PIC2008 Perugia 20

21 Cosmic muon event The detector is ready! 27 June 2008 Dirk Wiedner at PIC2008 Perugia 21

22 Initial minimum bias run only 4 filled bunches at L = 1.1 x cm -2 s -1 2 khz minimum bias to disk 300 Hz non-empty minimum bias events to disk 10 8 events in approx. 100 hours of running Filling scheme for next step (2008) k b Parameters Rates in 8 beta* Luminosity Events/ N (m) (cm -2 s -1 ) crossing E E E E June 2008 Dirk Wiedner at PIC2008 Perugia 22

23 Physics reach vs integrated σε/σ mb luminosity 1.E+01 π ± production 1.E+00 1.E-01 π 0 production 10 8 minimum 2kHz 1.E-02 K 0 production Λ production 1.E-03 Λbar production 1.E-04 φ production D-meson production 1.E-05 J/Ψ production 1.E-06 J/Ψ from bb 1.E-07 1.E-08 B 1.E-09 d J/ΨK s production 1.E-10 N mb 1.E+00 1.E+02 1.E+04 1.E+06 1.E+08 1.E+10 1.E+12 1.E June 2008 Dirk Wiedner at PIC2008 Perugia 23

24 Beauty x-section Requirement: working MUON-system, Main Tracker and VeLo measure J/Ψ -production cross sections disentangle fractions of prompt and detached J/Ψs relate non promt J/Ψ yield to bb cross sections 27 June 2008 Dirk Wiedner at PIC2008 Perugia 24

25 Summary The LHCb detector is ready to take data in 2008: Good decay time resolution to resolve B s oscillations Good mass resolution to efficiently suppress background Excellent particle identification for K-π separation Efficient trigger for many B-decay topologies Inclusive low p T physics from day one Determination of the b-cross section in first months 27 June 2008 Dirk Wiedner at PIC2008 Perugia 25

26 Outlook Physics program in 2009: Very interesting results with first 0.5 fb -1 of data: B s J/ s measurement with 0.05 precision (S.M. exp ) B s BR limit down to SM value ( ) x10-9 B d K 0* 1800 events, overtaking B-Factories statistics Core physics 2fb -1 per year CP Violation - 1 year (2 fb -1 ) Rare Decays - 1 year (2 fb -1 ) from trees: 5 o - 10 o from penguins: 10 o B s mixing phase: s eff from penguins: 0.11 B d K 0 * s 0 : 0.5 GeV 2 B s φ A dir, A mix : 0.11 A : 0.22 B s BR.: 6 x 10-9 at 5 If N.P.! 27 June 2008 Dirk Wiedner at PIC2008 Perugia 26

27 The End 27 June 2008 Dirk Wiedner at PIC2008 Perugia 27

28 s = 7 TeV LHCb: L=2-5 x cm -2 s -1 bb = 500 b inel / bb = 160 => 1 year = 2 fb -1 ALICE CERN ATLAS CMS LHCb A Large Hadron Collider Beauty Experiment for Precision Measurements of CP-Violation and Rare Decays 27 June 2008 Dirk Wiedner at PIC2008 Perugia 28

29 LHCb detector Particle ID: RICH: PID K, separation Calorimeter: PID: e,, 0 Muon System Tracking: Vertex Locator: primary + secondary vertex impact parameter Trigger Tracker: pt for Trigger Tracking Stations: pt of charged particles 27 June 2008 Dirk Wiedner at PIC2008 Perugia 29

30 Luminosity (1/4) Massimiliano FERRO-LUZZI 27 June 2008 Dirk Wiedner at PIC2008 Perugia 30

31 Luminosity (2/4) Beam shape and position measurement Use beam-gas interaction vertices Vertex locator resolution 30 µm in x and y, depending on # of tracks 10-7 mbar Xenon or other noble gas 30 Hz beam-gas collision rate 27 June 2008 Dirk Wiedner at PIC2008 Perugia 31

32 Luminosity (3/4) Bunch profile mapping within minutes O(1%) Normalize beam-beam x- section on beam-gas x- section Absolute luminosity during physics run feasible but calibration run advisable or L0 trigger on activity for any z --- beam1-gas beam2-gas beam1-beam2 sum ALL from: Massimiliano FERRO-LUZZI [m] 27 June 2008 Dirk Wiedner at PIC2008 Perugia 32

33 Z μ + μ - events Tara Shears Efficiency = 91% Purity = 97±3% 180 events per pb -1 5 pb -1 3 % statistical error. Total L error 5% if data understood 27 June 2008 Dirk Wiedner at PIC2008 Perugia 33

34 LHCb Unique phase space covered by LHCb Z and W differential crosssection from Z µ + µ -, W µν 10pb -1 enough for improvement on PDF uncertainties, today up to 50% Z 0 µ + µ - 27 June 2008 Dirk Wiedner at PIC2008 Perugia 34