1 / 35

b Production Cross Section and Fragmentation Fractions at LHCb

b Production Cross Section and Fragmentation Fractions at LHCb. Motivation LHCb b-cross section Semi- leptonic B 0/+ →D 0 X μν J/ ψ b →J/ ψ X Fragmentation fractions f s / f d Semi- leptonic B (s) 0/+ →D (s) +/0 X μν Hadronic B 0 s →D s - π + and B 0 →D - π + /K +.

carina
Download Presentation

b Production Cross Section and Fragmentation Fractions at LHCb

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. b Production Cross Section and Fragmentation Fractions at LHCb • Motivation • LHCb • b-cross section • Semi-leptonic B0/+→D0Xμν • J/ψ b →J/ψX • Fragmentation fractions fs/fd • Semi-leptonicB(s)0/+→D(s)+/0Xμν • Hadronic B0s→Ds-π+andB0→D-π+/K+ Niels Tuning on behalf of the LHCb collaboration Amsterdam, 5 April 2011

  2. Motivation b cross section: • Comparison to QCD predictions • Knowledge of b-yield to ascertain sensitivities in B-physics analyses Fragmentation fractions, fs/fd: • Input to e.g. inclusive b cross section measurement • Needed for allBs0 branching ratios • In particular BR(B0s→ μ+μ-) Number of measured Bs0decay modes is limited: + LHCb: Γi : Bs0→K*0K*0 Γi : Bs0→D0K*0 Γi : Bs0→Ds2 (2573)μν Γi : Bs0→ J/ψf0 (980) b cross section and fs/fd at LHCb

  3. The LHCb Detector 23 sep 2010 19:49:24 Run 79646 Event 143858637 b cross section and fs/fd at LHCb

  4. The LHCb Detector B0(s)→D(s)Xμν PID B(s)0→D(s)-K/π Lifetime, B0(s) RICH1 T MAGNET TT VELO MUON CALO RICH2 Interaction Point Suppress background, σ(MB) B(s)0 →D(s)-K/π Trigger & PID: B(s)0→ D(s)-K/π See also Neville Harnew. Monday 10:10, LHCb detector performance b cross section and fs/fd at LHCb

  5. LHC and LHCb performance • LHC and LHCb show excellent performance • Recorded 38 pb-1 • 1010bb-pairs produced effLHCb = 90.3% fs/fd (35 pb-1) hadronic b cross section J/ (5 pb-1) fs/fd (3 pb-1) semi-leptonic b cross section semi-lep (15 nb-1) b cross section and fs/fd at LHCb

  6. b cross section: semi-leptonic LHCb Collaboration, R.Aaij et al., Phys.Lett.B694:209-216,2010, arXiv:1009.2731 • Measure pp→bbXthrough • b→D0Xμ-ν D0→K-π+ • Distinguish b from prompt using impact parameter: Prompt D0: D0 from b: For more semi-leptonics, see : Rob Lambert. Thursday 9:25, Semileptonic decays (beauty/charm) & plans at LHCb b cross section and fs/fd at LHCb

  7. b cross section: semi-leptonic LHCb Collaboration, R.Aaij et al., Phys.Lett.B694:209-216,2010, arXiv:1009.2731 • Measure pp→bbXthrough • b→D0Xμ-ν D0→K-π+ • 2D unbinned likelihood fit to m(Kπ) and ln(IP) D0 mass D0 impact parameter Large impact parameter: from b For more semi-leptonics, see : Rob Lambert. Thursday 9:25, Semileptonic decays (beauty/charm) & plans at LHCb b cross section and fs/fd at LHCb

  8. b cross section: semi-leptonic • Measure pp→bbXthrough • b→D0Xμ-ν D0→K-π+ D0 impact parameter: (D0μ)-pairs Background: K and μ withopposite charge D0 impact parameter b cross section and fs/fd at LHCb

  9. b cross section: semi-leptonic • Measure pp→bbXthrough • b→D0Xμ-ν D0→K-π+ • Result (2<η<6): σ(pp→bbX) = 75.3±5.4±13.0 μb (assuming LEP fragmentation fractions) σ(pp→bbX) = 89.6±6.4±15.5 μb (assuming Tevatron fragmentation fractions) • Extrapolate to full rapidity range: HFAG, D. Asner et al., arXiv:1010.1589  CDF, Phys.Rev.D77:072003,2008., arXiv:0801.4375 x 2.9 nb-1microbias 12.2 nb-1triggered (MCFM v5.8, Campbell, Ellis) - combined Cacciari, Nason, Frixione, Mangano, Ridolfi e.g. hep-ph/9803400 Theoretical error (e.g. mb and μR,F) • NB: translation to b→D0Xμ-ν • depends on BR and fs/fd: • B0→D*-Xμ+ν → D0Yμ+ν • B+ → D0Xμ+ν • B0s→Ds*-Xμ+ν → D0Yμ+ν LHCb, 15.1 nb-1 LHCb Collaboration, R.Aaij et al., PLB694:209-216,2010, arXiv:1009.2731 b cross section and fs/fd at LHCb

  10. b cross section: J/ψ’s • Measure pp→bbXthrough • b→J/ψ(μ-μ+)X LHCb Collaboration, R.Aaij et al., Submitted to EPJ C, arXiv:1103.0423 LHCb Collaboration, R.Aaij et al., Submitted to EPJ C, arXiv:1103.0423 Large tz bkgd: from semi-lep b See also: Jibo He, Wednesday 10:00, J/ψ cross section (incl. B→J/ψX) and J/ψ polarization at LHCb b cross section and fs/fd at LHCb

  11. b cross section: J/ψ’s • Measure pp→bbXthrough • b→J/ψ(μ-μ+)X • Double differential cross section: LHCb Collaboration, R.Aaij et al., Submitted to EPJ C, arXiv:1103.0423 See also: Jibo He, Wednesday 10:00, J/ψ cross section (incl. B→J/ψX) and J/ψ polarization at LHCb b cross section and fs/fd at LHCb

  12. b cross section at LHCb • Measure pp→bbXthrough • b→D0Xμν • b→J/ψX • Good agreement among both measurements LHCb Collaboration, R.Aaij et al., Phys.Lett.B694:209-216,2010, arXiv:1009.2731 J/ from b √s=7 TeV LHCb 5.1 pb-1 (MCFM v5.8, Campbell, Ellis) LHCb Collaboration, R.Aaij et al., Submitted to EPJ C, arXiv:1103.0423 Cacciari, Nason, Frixione, Mangano, Ridolfi Theoretical error (e.g. mb and μR,F) BR(b→J/ X) =1.16% Assuming frag. fractions from LEP LHCb 15.1 nb-1 yJ/ b • NB: both measurements have many correlated errors, e.g. luminosity (10%), tracking eff.(8%), etc. b cross section and fs/fd at LHCb

  13. b cross section at LHCb • Measure pp→bbXthrough • b→D0Xμν • b→J/ψX • Good agreement among both measurements • Good agreement with QCD predictions LHCb Collaboration, R.Aaij et al., Phys.Lett.B694:209-216,2010, arXiv:1009.2731 (MCFM v5.8, Campbell, Ellis) Cacciari, Nason, Frixione, Mangano, Ridolfi e.g. hep-ph/9803400 Cacciari, Nason, Frixione, Mangano, Ridolfi Theoretical error (e.g. mb and μR,F) LHCb 15.1 nb-1 LHCb Collaboration, R.Aaij et al., Submitted to EPJ C, arXiv:1103.0423 b b cross section and fs/fd at LHCb

  14. Motivation b cross section: • Comparison to QCD predictions • Knowledge of b-yield to ascertain sensitivities in B-physics analyses Fragmentation fractions, fs/fd: • Input to e.g. inclusive b cross section measurement • Needed for allBs0 branching ratios • In particular BR(B0s→ μ+μ-) Two methods: • Semi-leptonic: B0/+(s)→ D(s)+/0 X μν • Hadronic: B0(s) → D(s)- π+/K b cross section and fs/fd at LHCb

  15. Motivation: BR(B0s→μμ) • Branching Ratio very sensitive to NP models • BR strongly enhanced in MSSM at large tanβ: tan6/mA4 A.Buras, G.Isidori, P.Paradisi Phys.Lett.B694:402-409,2011 E.g. G.Isidori & P.Paradisi , Phys.Lett.B639:499-507,2006. • BR(B0s→μμ) determined by normalizing wrt. known decay: fd/fs: Largest uncertainty in BR determination fd/fs: in principle environment dependent LHCb needs to measure it See also: Matteo Palutan, Thuesday 9:00 Bs→μμ, B →K*μ and B →sγ at LHCb b cross section and fs/fd at LHCb

  16. Ratio of fragmentation fractions fs/fdSemi-leptonic • Strategy: • Uncertainties: • Branching ratio BR(Ds) • Bs detection eff • BR(Bs→D0KXμν) • Tracking, PID, Trigger efficiency N(D0) from b: 28474±190 D0 N(D+) from b: 9406±105 D+ N(Ds+) from b: 2208±61 Ds+ LHCb, 3 pb-1 • Updated results expected soon b cross section and fs/fd at LHCb

  17. Extra: BR(Bs0→Ds2*-Xμ+ν) first observation LHCb Collaboration, R.Aaij et al., Phys.Lett.B698:14-20,2011, arXiv:1102.0348 Ds2*+(2573) m(Ds2*+)=2569.4±1.6 MeV b cross section and fs/fd at LHCb

  18. Ratio of fragmentation fractions fs/fd Novel Method • Find decay that is • Theoretically well understood • Experimentally clean Bs→Ds-π+andB0→D-K+ • U-spin related decays • Pure tree diagrams, factorization expected to work well • Factorization OK to ~10% (branching ratio level, estimated from data) • Non-factorizable U-spin breaking effects <2% (estimated from data) • Ratio of form factors can be improved • U-spin breaking effects: ~16-32% effect (branching ratio level) • Need to know to relative 20% ( lattice QCD? ) to match experiment R. Fleischer, N. Serra, N.T, Phys.Rev.D82:034038,2010 Blasi, et al Phys.Rev. D49 (1994) 238-246 b cross section and fs/fd at LHCb

  19. Ratio of fragmentation fractions fs/fd Novel Method • Find decay that is • Theoretically well understood • Experimentally clean Bs→Ds-π+andB0→D-K+ R. Fleischer, N. Serra, N.T, Phys.Rev.D82:034038,2010 • Na =1.00±0.02Non-factorizable U-spin breaking effects <2% (estimated from data) • NF=1.24±0.08 Need to know to relative 20% to match experiment ( lattice QCD?) Blasi, Colangelo, Nardulli, Paver Phys.Rev. D49 (1994) 238-246, hep-ph/9307290 b cross section and fs/fd at LHCb

  20. Ratio of fragmentation fractions fs/fd Novel Method (2) d • Find decay that is • Theoretically well understood • Experimentally clean Bs→Ds-π+andB0→D-π+ π R. Fleischer, N. Serra, N.T, Phys.Rev.D83:014017,2011 π π π • Na =1.00±0.02Non-factorizable U-spin breaking effects <2% (estimated from data) • NF=1.24±0.08 Need to know to relative 20% to match experiment • NE=0.966±0.075 Extra correction due to exchange diagram: R. Fleischer, N. Serra, N.T, Phys.Rev.D83:014017,2011 b cross section and fs/fd at LHCb

  21. Measurement of N(B0→D-K+) and N(Bs0→Ds-π+) • Data set: 35 pb-1 from 2010 • Multivariate selection • Likelihood fit to m(KKππ) • Special care for misidentified B0→D-(π→K+) background: B0→D-(π+→K) N(B0→D-K+)=253±21 Bd→Dπ b cross section and fs/fd at LHCb

  22. Measurement of N(B0→D-K+) and N(Bs0→Ds-π+) • Data set: 35 pb-1 from 2010 • Multivariate selection • Likelihood fit to m(KKππ) • Special care for misidentified B0→D-(π→K+) background N(Bs0→Ds-π+)=670±34 N(B0→D-K+)=253±21 b cross section and fs/fd at LHCb

  23. Measurement of N(B0→D-π+) and N(Bs0→Ds-π+) • Data set: 35 pb-1 from 2010 • Multivariate selection • Likelihood fit to m(Kπππ) N(Bs0→Ds-π+)=670±34 N(B0→D-π+)=4109±75 b cross section and fs/fd at LHCb

  24. Measurement of N(B0→D-π+) and N(Bs0→Ds-π+) • Data set: 35 pb-1 from 2010 • Multivariate selection • Likelihood fit to m(Kπππ) N(Bs0→Ds-π+)=670±34 N(B0→D-π+)=4109±75 • Extra: ratio BR(B0→D-K+)/BR(B0→D-π+)  world best BR(B0→D-K+) See also: Steve Blusk, Thursday 12:15 Bs →DsK and DK states at LHCb b cross section and fs/fd at LHCb

  25. Ratio of fragmentation fractions fs/fd • Uncertainties from • Fit • PID calibration • Reconstruction eff. difference K, π • Branching ratio BR(Ds) b cross section and fs/fd at LHCb

  26. Ratio of fragmentation fractions fs/fd B0→D-K+ B0→D-π+ N(B0→D-π+)=4109±75 N(B0→D-K+)=253±21 N(Bs0→Ds-π+)=670±34 b cross section and fs/fd at LHCb

  27. Ratio of fragmentation fractions fs/fd B0→D-K+ B0→D-π+ Combined: ( LHCb preliminary ) N(B0→D-π+)=4109±75 N(B0→D-K+)=253±21 N(Bs0→Ds-π+)=670±34 b cross section and fs/fd at LHCb

  28. fs/fd compilation Disclaimer: private compilation LHCb B0→DK: fs/fd = 0.242 ± 0.034 LHCb B0→Dπ: fs/fd = 0.249 ± 0.035 LHCb hadronic: fs/fd = 0.245 ± 0.031 . LHCb semi-leptonic: fs/fd = 0.260 ± 0.027 CDF (La Thuile 2011): fs/fd = 0.269 ± 0.033 (updated semi-lep [PRD77] with BR(Ds→φπ)) HFAG (CDF): fs/fd = 0.327 ± 0.039 (updated Mar 2011, semi-lep + avg.mix.χ) (NB: avg.mix.χ to be updated) HFAG (LEP): fs/fd = 0.256 ± 0.026 HFAG (ALL): fs/fd = 0.270 ± 0.034 LHCb 2010 Preliminary (NB: old avg.mix χ) See : Robert Harr, Monday 12:15 CDF Measurement of Time-Integrated Mixing: χold = 0.147 ± 0.011 χnew = 0.126 ± 0.008 χLEP = 0.1259± 0.0042 b cross section and fs/fd at LHCb

  29. fs/fd compilation Disclaimer: private compilation LHCb B0→DK: fs/fd = 0.242 ± 0.034 LHCb B0→Dπ: fs/fd = 0.249 ± 0.035 LHCb hadronic: fs/fd = 0.245 ± 0.031 . LHCb semi-leptonic: fs/fd = 0.260 ± 0.027 CDF (La Thuile 2011): fs/fd = 0.269 ± 0.033 (updated semi-lep [PRD77] with BR(Ds→φπ)) HFAG (CDF): fs/fd = 0.327 ± 0.039 (updated Mar 2011, semi-lep + avg.mix.χ) (NB: avg.mix.χ to be updated) HFAG (LEP): fs/fd = 0.256 ± 0.026 HFAG (ALL): fs/fd = 0.270 ± 0.034 LHCb 2010 Preliminary (NB: old avg.mix χ) →σ(fs/fd)~13% Outlook: 5σNP discovery potential of BR(B0s→μμ) (with σ(fs/fd)~7% ) down to 2x BRSM →σ(fs/fd)~7% R. Fleischer, N. Serra, N.T, Phys.Rev.D82:034038,2010 See also: Matteo Palutan, Thuesday 9:00 Bs→μμ, B →K*μ and B →sγ at LHCb b cross section and fs/fd at LHCb

  30. Summary Wealth of results from LHCb 2010 running: • b cross section: • σ(pp→bbX) = 284±20±49 μb • σ(pp→bbX) = 288± 4±48 μb • extra's: • First observation BR(Bs0→Ds2*-Xμ+ν) • World best BR(B0→D-K+) • fragmentation fractions, fs/fd: • fs/fd = 0.242 ± 0.024 ± 0.018 ± 0.016 • fs/fd = 0.249 ± 0.013 ± 0.020 ± 0.025 • fs/fd = 0.245 ± 0.017 ± 0.018 ± 0.018 • fs/fd = 0.260 ± 0.008 ± 0.026 (stat) (sys) (theo) b→D0Xμ+ ν b→J/X Bs0→Ds2*-Xμ+ν B0→D-K+ B0→D-K+ B0→D-π+ B0→D-h+ B0→D-Xμ+ ν b cross section and fs/fd at LHCb

  31. Backups b cross section and fs/fd at LHCb

  32. LHCb Papers LHCb Collaboration, R.Aaij et al., Phys.Lett.B698:14-20,2011, arXiv:1102.0348 LHCb Collaboration, R.Aaij et al., Submitted to EPJ C, arXiv:1103.0423 LHCb Collaboration, R.Aaij et al., Phys.Lett.B694:209-216,2010, arXiv:1009.2731 b cross section and fs/fd at LHCb

  33. fs/fd compilation Disclaimer: private compilation LHCb B0→DK: fs/fd = 0.242 ± 0.034 LHCb B0→Dπ: fs/fd = 0.249 ± 0.035 LHCb hadronic: fs/fd = 0.245 ± 0.031 . LHCb semi-leptonic: fs/fd = 0.260 ± 0.027 CDF (La Thuile 2011): fs/fd = 0.269 ± 0.033 (updated semi-lep [PRD77] with BR(Ds→φπ)) HFAG (CDF): fs/fd = 0.327 ± 0.039 (updated Mar 2011, semi-lep + avg.mix.χ) (NB: avg.mix.χ to be updated) HFAG (LEP): fs/fd = 0.256 ± 0.026 HFAG (ALL): fs/fd = 0.270 ± 0.034 LHCb 2010 Preliminary (NB: old avg.mix χ) HFAG March 2011: b cross section and fs/fd at LHCb

  34. Factorization R. Fleischer, N. Serra, N.T, Phys.Rev.D83:014017,2011 • Factorization works to better then 5% • Deviation from semileptonic rate is small • Na under control b cross section and fs/fd at LHCb

  35. fd/fs from CDF Factorization and SU(3) symmetry OK Deviation from semi-leptonic rate is small d↔s symmetry OK (compare B→DK and B→Dπ) Can even use B0→D+π-instead of B0→D+K- CDF (PDG) CDF, Phys. Rev. Lett. 98 (2007) 061802 CDF (FST) R. Fleischer, N. Serra, N.T, Phys.Rev.D83:014017,2011 b cross section and fs/fd at LHCb

More Related