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Burkhard Schmidt, CERN on behalf of the LHCb Collaboration

Burkhard Schmidt, CERN on behalf of the LHCb Collaboration. LHCb - Physics Summary. Hadron Collider Physics Symposium Kyoto, November 12-16, 2012. LHCb physics results.

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Burkhard Schmidt, CERN on behalf of the LHCb Collaboration

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  1. Burkhard Schmidt, CERN on behalf of the LHCb Collaboration LHCb - Physics Summary Hadron Collider Physics Symposium Kyoto, November 12-16, 2012

  2. LHCb physics results • Search for potential effects of physics beyond the Standard Model in CP violation and rare decays using charm and beauty hadrons • CP violation in B system (B+, B0, Bs) : • Measurement of γ in tree-level processes S. Ricciardi in HF session • Measurement of γ in loop-mediated processes (charmless B decays) • CP violation in Bsmixing, φsphase M. Versterinen in HF session • Charm studies • CP violation and mixing in charmA. Di Canto in HF session • Rare decays • B0d,s μ+μ- , K0s μ+μ- , D0 μ+μ-J. Albrecht in HF session • B0 K*0 μ+μ- , τ  μμμ, etc. and T . Blake in SUSY session • The physics programme includes also: • Quarkonium studies • Production and spectroscopy of heavy flavour • Soft QCD physics A. Contu in QCD session • Electroweak physicsK. Rinnert in EW session HCP 2012 - Kyoto, November 12-16, 2012

  3. Selection of LHCb Physics results LHCb obtained many more exciting results not covered in this talk – apologies. 78 papers submitted to journals and >100 conference contributions up to now http://cdsweb.cern.ch/collection/LHCb%20Papers?ln=en Unless otherwise stated, the results are based on 1/fb of data collected in 2011 at 7 TeV center of mass energy. • Outline of this talk: • CP violation in B system (B+, B0, Bs) : • Measurement of γ in tree-level processes Recent result • Charm studies • Observation of D0- Do mixing New result • Rare decays • B0d,s μ+μ- , New result, next talk • K0s μ+μ-, B0 K*0 μ+μ- • Electroweak physics • Z→ ττproductioncross section Recent result • Soft QCD physics • pA test run HCP 2012 - Kyoto, November 12-16, 2012

  4. CP violation in the B system and measurement of γ HCP 2012 - Kyoto, November 12-16, 2012

  5. CP violation phenomenology CP violation in decay (direct) Asymmetry in decay amplitudes for a process and its conjugate: | Af/ Af | ≠ 1 The only possibility for charged mesons CP violation in mixing (indirect) If transitions B0B0are allowed CP violation if | q / p | ≠ 1 Rate of B0B0differs from B0 B0 CP violation in interference between mixing and decay (indirect) Even if | Af/ Af | = 1 and | q / p | = 1 , CP is violated if Can be measured in the time dependent asymmetry: HCP 2012 - Kyoto, November 12-16, 2012

  6. CKM measurements: current status • Area of CKM triangle is proportional to the amount of CP violation in the model. • All CP violation phenomena in SM are the result of a single phase in the CKM matrix. • Precision of some measurements are much worse than the others. Notably, γ, is the least well-measured angle of the Unitarity Triangle. • γ can be measured in tree- and loop-level decays. Tree-level decay:  SM benchmark measurement of γ Loop-level decays:  Measurement of γ sensitive to NP LHCb can do all of them HCP 2012 - Kyoto, November 12-16, 2012

  7. CP violation in BDK: SM benchmark γ v • Measurement of partial width of B DK decays allows to determine γ • Sensitivity to γ from interference between the 2 diagrams • Only requirement: D0 and D0 decay to the same final states • Decay modes used: • D in CPeigenstates(D0K+K-, π+π-) [PLB 712 (2012) 203] Gronau-London- Wyler (GLW) [PLB 265, 172 (1991)] • Cabibbo allowed (D0 K- π+)and double Cabibbo suppressed states (D0 K+ π- and D0 K+ π-π+π- )New[LHCb-CONF-2012-030] Atwood-Dunietz-Soni (ADS) [PRL 78, 3257 (1997)] • D in 3-body decays (D0  Ksπ+π-) New[PLB 718 (2012) 43] Giri-Grossmann-Soffer-Zupan (GGSZ, Dalitz)[ PRD 68, 054018 (2003] HCP 2012 - Kyoto, November 12-16, 2012

  8. Measurable parameters s Measured ratios and asymmetries for GLW: For ADS modes additional amplitude rD and phase δD enter from D decay: GGSZ analysis: Fits distribution of events in the D K0hh Dalitz plot: K±i– flavour tagged yield in the ith bin, ci, si CLEO inputs  Each analysis measures different parameters containing complementary information about γ. HCP 2012 - Kyoto, November 12-16, 2012

  9. CP violation in B DK, Dhh’decays B+ D0K+ and B+ D0K+ followed by D K+K- decay Suppressed B+ D0K+ followed by allowed D0 K-π+ interferes with allowed B+ D0K+ followed by suppressed D0 K-π+ decay [PLB 712 (2012) , 203] 4.5σ 4.0σ HCP 2012 - Kyoto, November 12-16, 2012

  10. CP violation in B DK, D K3π decays [LHCb-CONF-2012-030] ± • Suppressed ADS B± D(π± Kπ+π-) / K± π± mode • First observation of suppressed ADS B± D(π± Kπ+π-) K± mode: 40 candidates (5.1 σ) • First observation of suppressed ADS B± D(π± Kπ+π-) π± mode: 155 candidates (> 10 σ) • Hints of asymmetries in both modes RKADS = (1.24 ± 0.27) % RπADS = (0.369 ± 0.036) % AKADS = (-42 ± 22) % Aπ ADS = (13 ± 10) % pl HCP 2012 - Kyoto, November 12-16, 2012

  11. GGSZ analysis: B DK, D K0hh s s v Model-independent Dalitz plot analysis of DK0h+h- from BDK Divide phase space into bins and work with the number of events in each bin Binning scheme chosen to maximise sensitivity to γ Strong phase variation from correlated D-D pairs measured at CLEO-c [PLB 718 (2012) 43] [PRD 82 (2012) 112006] Candidates after the selection: ~690 D K0sππ~110 D K0sKK HCP 2012 - Kyoto, November 12-16, 2012

  12. GGSZ analysis: B DK, D K0hh • Count number of events in binned plots (separately for B+ and B-) in D K0sπ πand D K0sKK plots. • Asymmetry in the number of events in bins manifests CP-violation Maximum likelihood fit to obtain x± and y± x_ = (0.0 ± 4.3 ± 1.5 ± 0.6) x 10-2 x+= (2.7 ± 5.2 ± 0.8 ± 2.3) x 10-2 y_= (-10.3 ± 4.5 ± 1.8 ± 1.4) x 10-2 y+= (-0.9 ± 3.7 ± 0.8 ± 3.0) x 10-2 x± = rBcos(±γ+δB) y± = rBsin(±γ+δB) HCP 2012 - Kyoto, November 12-16, 2012

  13. γ combination result [LHCb-CONF-2012-032] -15.7 Combination of BDK modes with 1/fb gives: γ = ( 71.1 +16.1 )o [43.9o – 98.8o ] @ 95% C.L. Comparable to individual results of Babar and Belle World average: γ = (66 ±12)o (CKMFitter 2012) Further 2/fb will be in hand by the end of 2012 Additional information will come from the determination of γ in time dependent analyses. HCP 2012 - Kyoto, November 12-16, 2012

  14. Charm studies: D0 – D0mixing HCP 2012 - Kyoto, November 12-16, 2012

  15. Measurement of D0 – D0mixing [arXiv 1211.1230] Subm to PRL ; x= Δm/Γ y=Δ Γ/2Γ • Very interesting because it probes NP which couples to up-quarks. • So far evidence for charm mixing in BaBar, Belle and CDF, but observation greater than 5σ only when results are combined. • This result: Observation of D0 – D0 oscillations with ‘wrong sign’ D*+ D0(K+π-) π+ decays • WS events through either direct DCS decays or mixing followed by CF • RS events dominated by CF • Assuming |x| , |y| << 1 , and negligible CPV: HCP 2012 - Kyoto, November 12-16, 2012

  16. D0 – D0mixing – D*yields ~36k WS ~8.4M RS Time integrated D0πs mass distributions for RS and WS candidates HCP 2012 - Kyoto, November 12-16, 2012

  17. D0 – D0mixing – Analysis details • Count WS and RS events in 13 decay time bins • Fit the ratio of yields as function of the decay time • Fit strategy: • Tight cut on D0 mass • Fit first clean RS sample to determine signal shape • Then fit WS sample with the signal shape fixed by RS sample • Calculate WS/RS ratio R • Systematics: • Relevant sources are those which could bias observed time-dependence on R: • Secondary D-mesons and bkg. from mis-ID charm decays peaking in M(D0πs) HCP 2012 - Kyoto, November 12-16, 2012

  18. D0 – D0mixing – Result First observation of D0 - D0mixing • Mixing parameters: RD = (0.352 ± 0.015)% y’ = (0.72 ± 0.24)% x’2 = -(0.009 ± 0.013)% • p-value = 5.67 x 10-20 • No mixing hypothesis excl. at 9.1σ • Comparison with other experiments: HCP 2012 - Kyoto, November 12-16, 2012

  19. Rare decays HCP 2012 - Kyoto, November 12-16, 2012

  20. Rare Decays – Introduction [arXiv 1208.0934 and arXiv:1204.1737] Flavour physics observables have sensitivity to new particles at high mass scales via their indirect effects in loop diagrams B0s μ+μ- SM: NP: FCNC, helicity suppressed Sensitive to NP contributions SM expectation: (3.54±0.30) x 10-9 MSSM: BR (B0s μ+μ-)~tan6/M4A B0 K*0 μ+μ- SM: NP: FCNC, BR (PDG) = (1.05±0.15)x 10-6 Angular observables sensitive to modification of the helicity structure HCP 2012 - Kyoto, November 12-16, 2012

  21. Update on search for B0(s) μ+μ- • New analysis using 1.1/fbof the 2012 data set plus 1/fb from 2011 • Same analysis strategy as in 2011 [PRL 108 (2012) 231801] with only minimal changes • Improvements: [Subm to arXiv and PRL today] • Refined estimate of the exclusive backgrounds • BDT output calibrated on exclusive B(s) h+h-(instead of inclusive) Analysis will be presented by J. Albrecht HCP 2012 - Kyoto, November 12-16, 2012

  22. Update on search for B0(s) μ+μ- New result First evidence of B0s μ+μ- • New analysis using 1.1/fbof the 2012 data set plus 1/fb from 2011 • Same analysis strategy as in 2011 [PRL 108 (2012) 231801] with only minimal changes • Improvements: [Subm to arXiv and PRL today] • Refined estimate of the exclusive backgrounds • BDT output calibrated on exclusive B(s) h+h-(instead of inclusive) Analysis will be presented by J. Albrecht HCP 2012 - Kyoto, November 12-16, 2012

  23. Search for K0 μ+μ- s [arxiv:1209.4029v2, Subm. JHEP] ππ hypothesis μμ hypothesis K0  π+π s s Yet unobserved FCNC decay with BR (SM) = (5.0±1.5) x 10-12 The current 90% CL experimental limit dates from 1973: BR < 3.2 x 10-7 Peaking background from K0  π+π-decays is shifted due to μ - π mass difference. Good mass resolution helps containing it. Discrimination through a BDT (geometrical and kinematic), trained on data and calibrated on K0  π+π-data HCP 2012 - Kyoto, November 12-16, 2012

  24. Search for K0 μ+μ- s s Normalisation to translate number of signal decays into a branching fraction: Use CLs method to determine an upper limit on the branching fraction BR (K0  μ+μ-) < 9(11) x 10-9 at 90 (95) % CL  35 times better than previous result Summary of all neutral flavoured mesons to μ+μ- decays: HCP 2012 - Kyoto, November 12-16, 2012

  25. Isospinasymmetry in B  K(*)μ+μ- [JHEP 07 (2012) 133] [JHEP 01 (2003) 074] The isospin asymmetry in BK(*)μ+μ- is defined as: It is predicted to be very small in the SM Integrated over q2 , over 4σ deviation from zero for B K μ+μ- 2012 data should allow errors to be halved. HCP 2012 - Kyoto, November 12-16, 2012

  26. Analysis of B+→K+μ+μ− • FCNC process, sensitive to modifications of the helicity structure [arxiv:1209.4284, Subm. JHEP] Decay rate can be expressed in terms of the angle θl between the μ- and the K+ in the dimuon rest frame: Event yield 1232 ± 40 of B+→K+μ+μin 1.0 fb-1 Differential branching fraction, using B+J/ψ K+as normalisation channel. Consistently below SM prediction at low q2. Integrating dB/dq2 gives BR(B+→K+μ+μ) = (4.36±0.18) x 10-7 HCP 2012 - Kyoto, November 12-16, 2012

  27. B+→K+μ+μ−angular analysis [arXiv:1209.4284, Subm. JHEP] • AFB expected to be zero in the SM, can be up to 0.15 in NP models • FH also close to zero in the SM, can be up to 0.5 in NP models • AFB and FH are determined from a simultaneous fit to mass and cos(θl) • The results are consistent with the SM HCP 2012 - Kyoto, November 12-16, 2012

  28. Other topics - Electroweak physics • Soft QCD physics • Upgrade potential HCP 2012 - Kyoto, November 12-16, 2012

  29. Z→ ττproductioncross-section • Z-production cross-section is an important verification of SM predictions • Inclusive W, Zμμproduction cross-sections published earlier this year • (from 37/pb data taken in 2010) [JHEP 06 (2012) 058] • New result: inclusive Z  ττcross section based on 2011 data set of 1/fb Signal topologies and channels [arXiv 1210.6289, Subm .JHEP] • Observed : 124 • Bkg : 42 • Signal : 82 σppZττ= 71.4 ± 3.5 (stat.) ± 2.8 (syst.) ± 2.5 (lumi.) pb HCP 2012 - Kyoto, November 12-16, 2012

  30. pA collisions in LHCb Test run with pA collisions on September 13 in all 4 LHC experiments Several hours of data taking with L ~ 5 x 1025cm2/s with stable conditions No problem of multiplicities in the detector, similar to pp collisions KS and Λ peaks reconstructed offline Good expectations for the January (pA, Ap) run HCP 2012 - Kyoto, November 12-16, 2012

  31. LHCb sensitivity to key flavour channels • Unique potential Bs / b baryon sector • Charged particle final states far in excess of other facilities [LHCb-PUB-2012-009] HCP 2012 - Kyoto, November 12-16, 2012

  32. Conclusions -15.7 A measurement of γ from a combination of B Dh± analyses has been presented. The obtained value of γ = (71.1 +16.6)oreaches the precision of the B-factories. Good prospects for precision measurement in the future. LHCb observed D0-D0 mixing. The no mixing hypothesis is excluded with a significance ff 9.1σ. The measurement agrees wit the one of other experiments, but has substantially better precision. LHCb observes an excess of Bs μμcandidates with respect t0 the background expectations. The upper limit on K0shas been improved by 35 times since the previous measurement,entering the region where constraint becomes interesting – though SM is still a long way to go. Measurements presented here use (mainly) the 2011 dataset of 1.0/fb. By the end of 2012, expect to triple the dataset, looking forward to new exciting results next spring. HCP 2012 - Kyoto, November 12-16, 2012

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