First results & Prospects for Charm Physics @ LHCb

1. First results & Prospects for Charm Physics @ LHCb Vanya BELYAEV (Nikhef, Amsterdam) on behalf of LHCb Collaboration

2. Outline For LHCb results on J/y see talk by Giovanni Passaleva, Prompt J/yand b →J/yXproduction in pp-collision at √s=7TeV, track#5, 22 July 9:30 • Why (open) Charm? • The first results Open Charm peaks Open Charm cross-section • Perspectives • Mixing & CP violation • yCP, ACP • Rare decays Vanya Belyaev (Nikhef)

3. Why charm? • Charm production in forward region 2<y<5 at LHC energy is an unique & unexplored domain • Rare decays (D0→m+m-), mixing and CP-violation are well suitable for NP search • Deep understanding of charm is nessessery for many crucial measurement with beauty D0→Ksppdecay model for GGSZ-measurement of angle-g of Unitarity Triangle through B→DK • Collecting experience, testing tools & skills, warming up for analyses of beauty Vanya Belyaev (Nikhef)

4. LHCb: forward spectrometer • Selection of good tracks: c2(track)/DoF • Use RICH to separate kaons from pions: DLL(K-p) for kaons, DLL(p-K)for pions • Pointing criteria for final state particles: • large c2 for impact parameter c2(IP) • Pointing criteria for mother particle • small c2 for impart parameter c2(IP) • small angleq between momentum and vector from origin to decay vertex • Large lifetime of charm particle • “large” c2of vertex separation: c2(flight) • “large” lifetime ct O(2nb-1) : minimum bias trigger O(14nb-1): “low-luminosity” Vanya Belyaev (Nikhef)

5. D0→ K-p+ and D*+→ (D0→K-p+ )p+ K,p : c2(track)/DoF < 10 K,pD : c2(IP) > 9 K : DLL(K-p) > 0 p : DLL(p-K) > 0 D0 : c2(vertex) <9 ct > 90 mm c2(IP) < 9 D*+ : c2(vertex)< 9 K,p : c2(track)/DoF < 9 c2(IP) > 9 pT > 700 MeV/c K : DLL(K-p) > p : DLL(K-p) D0 : c2(vertex) <9 c2(flight) > 16 c2(IP) < 9 q < 12 mrad Vanya Belyaev (Nikhef)

6. D+→K-p+p+ and Ds→ (f→K-K+)p+ K,p : Prob(c2(track)) > 10-4 pT > 200 MeV/c p > 3.2 GeV/c c2(IP) > 3.0 2 daugthters: pT > 400 MeV/c c2(IP) > 10 1 daughter: c2(IP) > 50 K : DLL(K-p) > 3.3 p : DLL(p-K) > -10 D+ : c2(vertex) <8 q < 14 mrad • c2(flight) > 90 • t < 0.01 ns K,p:c2(track)/DoF<4 K : c2(IP) > 2 p : c2(IP) > 10 K : DLL(K-p) > 9 p : DLL(p-K) > -2 f : |DM|<20MeV/c2 Ds : c2(vertex)/DoF<5 Ds : c2(flight)> 67 Vanya Belyaev (Nikhef)

7. From plots to cross-sections Eric van Herviinen LHCb Trigger System, track #1, 22 July, 10:15 Silvia BorghiPerformance of Tracking System of LHCb Experiment, track #1, 22 July, 11:36 Andrew Powell ParticleID @ LHCb, track #1, 22 July, 14:00 Measure the cross-section in bins of pT and rapidity • Luminosity: 1.81±0.18nb-1 • Efficiency: • Trigger: ‘no-trigger’ • Reconstruction Efficiency • Tracking efficiency from data • Particle Identification Efficiency • Determined on data using the clean Ks, L0 and f peaks • Selection efficiency: rely on Monte Carlo with the detailed cross-checks on data Vanya Belyaev (Nikhef)

8. Cascade charm b→c The similar technique has been used for measurement of beauty cross-section , see talk by Sheldon Stone, First physics results from LHCb, track #1, 23 July, 10:00 log(IP) • There is cascade production of open charm in decays of b→(D,D*,Ds) • The pointing criteria of D-mesons: log(IP) Vanya Belyaev (Nikhef)

9. Systematics Absolute luminosity: overall 10% Trigger efficiency/ “no-trigger” negligible Tracking efficiency: extract from data, conservatively: 3%/track Selection efficiency: variation of cuts, compare data and Monte Carlo: 0.5-4% Charm from beauty: ~5% Signal extraction, fits, binning effects: ~3% Particle ID efficiency: from data, cross-checked with no-PID selections: ~3% Vanya Belyaev (Nikhef)

10. D0 cross-section “shape” Theory: Cacciary M., Frixione, S., Mangano, M.,Nason, P. Ridolfi, G. Vanya Belyaev (Nikhef)

11. D*+cross-section Vanya Belyaev (Nikhef)

12. D+cross-section Vanya Belyaev (Nikhef)

13. Dscross-section Vanya Belyaev (Nikhef)

14. Other Charm peaks D*+→ ( D0→Ksp+p+)p+ D0→p+p- D+→Ksp+ D0→pp D*+→ ( D0→K-p+p+p-)p+ D0→K-p+p0 Vanya Belyaev (Nikhef)

15. Prospects with Charm O(50nb-1) D0→K+K- • Huge yields are expected for O(100pb-1) Vanya Belyaev (Nikhef)

16. Probe New Physics in charm Proper lifetime D0→Kp D0→ KK yCP from lifetime difference between D0→KK and D0→Kp Vanya Belyaev (Nikhef)

17. Probe New Physics in charm • Mixing parameters x’2 and y[LHCb-2007-049] N (D0→Kp, wrong sign) = 2.5×103 / 100 pb-1with B/S~2.5 • Search for direct CP-violation in D+ →K-K+p+ • Search for rare D0→m+m- expected UL 4×10-8 @ 90CL for 100 pb-1 Vanya Belyaev (Nikhef)

18. Summary • LHCb is a great detector for charm physics • High Rate • Good momentum and spatial resolution • Particle identification • LHCb has started successfully its charm physics program with the observation of charm peaks and measurement of open charm cross section • Year 2k+10 and 2k+11 • High statistics measurements in charm sector Stay tuned Vanya Belyaev (Nikhef)

19. The basic principles of event selection • Selection of good tracks: c2(track)/DoF • Use particle identification to separate kaons from pions • “large” DLL(K-p) for kaons, • “large” DLL(p-K)for pions • Pointing criteria for final state particles: • “large” c2 for impact parameter c2(IP) • Pointing criteria for mother particle • “small” c2 for impart parameter c2(IP) • small angle q between momentum and vector from origin to decay vertex • Large lifetime of charm particles • “large” c2of vertex separation: c2(flight) • “large” lifetime ct Vanya Belyaev (Nikhef)