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Recent Open Heavy Flavor Results from ATLAS and CMS Experiment at LHC

This presentation discusses the study of open heavy flavor production at the LHC, focusing on leptons from heavy quarks, non-prompt J/ψ, and exclusive B meson decays. The requirements for these studies, such as flexible trigger systems, muon/electron detection, secondary vertex reconstruction, and jet reconstruction, are also addressed. The results of these studies in pp and pPb collisions are presented, along with the suppression of heavy flavor in PbPb collisions.

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Recent Open Heavy Flavor Results from ATLAS and CMS Experiment at LHC

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  1. Yen-Jie Lee (MIT) For the ATLAS and CMS collaboration RHIC & AGS Annual Users’ Meeting BNL, Upton, USA 18 June, 2014 Recent Open Heavy Flavor Results from ATLAS and CMS Experiment at LHC RHIC & AGS Annual Users' Meeting

  2. Study of open heavy flavor production at the LHC (1/4) RHIC & AGS Annual Users' Meeting Leptons from heavy quarks μ+ μ- K+ Secondary vertex b Primary vertex SampleO(10%) of b cross-section

  3. Study of open heavy flavor production at the LHC (2/4) RHIC & AGS Annual Users' Meeting Non-prompt J/ψ Leptons from heavy quarks μ+ J/ψ μ- K+ Secondary vertex b Primary vertex Dileptons channel sample O(0.1%) of b cross-section

  4. Study of open heavy flavor production at the LHC (3/4) RHIC & AGS Annual Users' Meeting Non-prompt J/ψ Leptons from heavy quarks μ+ J/ψ μ- K+ Secondary vertex b Exclusive B meson decays Primary vertex J/ψ+1(2) tracks decay channels sample O(0.01%) of b cross-section

  5. Study of open heavy flavor production at the LHC (4/4) RHIC & AGS Annual Users' Meeting Non-prompt J/ψ Leptons from heavy quarks μ+ J/ψ μ- K+ Secondary vertex b Exclusive B meson decays Primary vertex b-jet reconstruction b-tagged jet sample O(100%)of b cross-section and ~70-90% of the b quark energy

  6. Requirements RHIC & AGS Annual Users' Meeting Non-prompt J/ψ Leptons from heavy quarks μ+ J/ψ μ- K+ Secondary vertex b Exclusive B meson decays Primary vertex b-jet reconstruction Requirement: flexible trigger system, muon / electron detection, secondary vertex reconstruction, jet reconstruction

  7. ATLAS detector RHIC & AGS Annual Users' Meeting

  8. RHIC & AGS Annual Users' Meeting |η|< 2.4 Muon |η|< 5.2 HCAL ECAL |η|< 3.0 Tracker |η|< 2.5 CMS detector EMandHadroncalorimeters photons, isolation, jet reco Pb Inner tracker: charged particles vertex, isolation solenoid Pb

  9. RHIC & AGS Annual Users' Meeting Bottom Production At NLO Excitation of sea quarks  b(b) + light dijet, w/ b(b) at beam rapidity Gluon splitting into b and b which can also be reconstructed as a single jet Bottom production at the LHC Flavor Creation (FCR) Flavor Excitation (FEX) Gluon Splitting (GSP) • LO b-b production (FCR) not dominant at the LHC arXiv:0705.1937 pp @ 14 TeV

  10. RHIC & AGS Annual Users' Meeting Flavor Creation Candidate (pp @ 7 TeV) Flavor Creation Candidate (pp @ 7 TeV) b b Reconstructed secondaryvertices from b and cquarks

  11. RHIC & AGS Annual Users' Meeting Gluon Splitting Candidate (pp @ 7 TeV) Gluon Splitting Candidate (pp @ 7 TeV) b g b

  12. Study of open heavy flavor production at the LHC (1/4) RHIC & AGS Annual Users' Meeting 1. Leptons from heavy quarks μ+ μ- K+ Secondary vertex b Primary vertex

  13. Heavy flavor muon identification RHIC & AGS Annual Users' Meeting Signal • Separate signal muons(heavy flavor meson decay) from pion and kaon decays • Momentum balance • Scattering angle significance Muon Spectrometer pMS μ μ Inner Detector pID π Background Take the maximum: ATLAS-CONF-2012-050

  14. Heavy flavor muon signal extraction RHIC & AGS Annual Users' Meeting • Composite discriminant • r = 0.07 • Signal extracted from atwo component fit ATLAS-CONF-2012-050

  15. Suppression of heavy flavor muons in PbPb RHIC & AGS Annual Users' Meeting ATLAS-CONF-2012-050 Muon RCP vs Npart (60-80% as reference) Muon RCP vs muon pT • Suppression of heavy flavor muons in central PbPb collisions with respect to peripheral events is observed ( RCP ~ 0.4) • RCP ~ constant vs. muon pT

  16. Study of open heavy flavor production at the LHC (2/4) RHIC & AGS Annual Users' Meeting 2. Non-prompt J/ψ μ+ J/ψ μ- K+ Secondary vertex b Primary vertex

  17. Inclusive J/ψ production in PbPb RHIC & AGS Annual Users' Meeting Non-prompt J/ψ to dimuon channel prompt J/ψ direct J/ψ J/ψψ’,χC inclusive J/ψ J/ψ B CMS PAS HIN-12-014

  18. Non-prompt J/ψ suppression in PbPb RHIC & AGS Annual Users' Meeting Suppression of non-prompt J/ψ in central PbPb collisions with respect to pp reference is observed ( RAA ~ 0.4) CMS PAS HIN-12-014

  19. Study of open heavy flavor production at the LHC (3/4) RHIC & AGS Annual Users' Meeting μ+ J/ψ μ- K+ Secondary vertex b 3. Exclusive B meson decays Primary vertex

  20. RHIC & AGS Annual Users' Meeting B meson reconstruction • B-meson reconstructed by combination of • J/y (decay to dimuon) • tracks (assigned pion or kaon mass, w/o PID) B0 • B+→ J/ψK+→μ+μ- K+ • B0→ J/ ψK0* →μ+μ- K+π- • Bs→ J/ ψφ→μ+μ- K+K- B+ Bs 449 20

  21. Open heavy flavor production in pp collisions RHIC & AGS Annual Users' Meeting 5 GeV ATLAS and CMS have reported B meson (b baryon) cross-section measurements in pp collisions (pT = 5 GeV to 100 GeV) Good agreement between pp data and FONLL calculation

  22. B meson production in pPb collisions at 5.02 TeV RHIC & AGS Annual Users' Meeting CMS PAS HIN-14-004 Three component fit for signal extraction: • Signal • Combinatorial background from J/ψ-track(s) • Non-prompt component from other B-meson decays that form peaking structures (e.g. in B+ analysis, bkg from B0→ J/ψK0* ) First fully reconstructed B meson signal in heavy ion collisions! B0J/ψK*0 B+J/ψK+ BsJ/ψφ

  23. RHIC & AGS Annual Users' Meeting B meson production in pPb collisions Raw yields are corrected by acceptance and efficiency CMS PAS HIN-14-004 Acceptance Efficiency 23

  24. RHIC & AGS Annual Users' Meeting Differential cross-section pp reference : FONLL calculation is used (agreement with CDF, ATLAS and CMS data) http://www.lpthe.jussieu.fr/~cacciari/fonll/fonllform.html |yCM|<1.93 B0 B+ Bs0 B0J/ψK*0 B+J/ψK+ BsJ/ψφ 24

  25. RHIC & AGS Annual Users' Meeting Nuclear modification factor : RpAFONLL RpAFONLL is compatible with unity within given uncertainties for the three B-mesons |yCM|<1.93 CMS PAS HIN-14-004 25

  26. Study of open heavy flavor production at the LHC (4/4) RHIC & AGS Annual Users' Meeting μ+ J/ψ μ- K+ Secondary vertex b Primary vertex 4. b-jet reconstruction (Anti-kT r=0.3) UE background subtracted

  27. Tagging and counting b-quark jets RHIC & AGS Annual Users' Meeting Secondary vertex tagged using flight distance significance Tagging efficiency estimated in a data-driven way Purity from template fits to (tagged) secondary vtx mass distributions CMS HIN-12-003 ArXiv 1312.4198 CMS PAS HIN-14-007

  28. b-jet RpAPYTHIA in pPb collisions at 5.02 TeV RHIC & AGS Annual Users' Meeting CMS PAS HIN-14-007 b-jet RpAPYTHIA is compatible with unity within given uncertainties

  29. b-Jet RAA in PbPb collisions at 2.76 TeV RHIC & AGS Annual Users' Meeting Suppression of b-tagged jets in central PbPb collisions with respect to pp reference was observed ( RAA ~ 0.5) CMS HIN-12-003 ArXiv 1312.4198

  30. Summary of open heavy flavor production in ATLAS and CMS RHIC & AGS Annual Users' Meeting 2. Non-prompt J/ψ 1. Leptons from heavy quarks μ+ J/ψ μ- K+ Secondary vertex b 3. Exclusive B meson decays Primary vertex 4. b-jet reconstruction

  31. Summary: RAA (CP) vs Npart RHIC & AGS Annual Users' Meeting CMS Non-prompt J/ψ RAA ATLAS Heavy Flavor Muon RCP ( 60-80% as reference)

  32. Summary: Flavor Dependence of Jet Quenching RHIC & AGS Annual Users' Meeting Indication of RAA(B) > RAA(D) > RAA(π) at low pT (However, spectra slope are different) D bJ/ψ π

  33. Summary: Flavor Dependence of Jet Quenching RHIC & AGS Annual Users' Meeting Indication of RAA(B) > RAA(D) > RAA(π) at low pT (However, spectra slope are different) D bJ/ψ π Replace non-prompt J/ψ results by exclusive B meson to fix the x axis scale

  34. Summary: Flavor Dependence of Jet Quenching RHIC & AGS Annual Users' Meeting Indication of RAA(B) > RAA(D) > RAA(π) at low pT (However, spectra slope are different) Indication of RAA(b-jet) ~ RAA(all jets) at high jet pT b-jet D bJ/ψ π b quark jet ~ inclusive jet (mainly gluon jets), contribution from gluon splitting?

  35. Outlook: Statistical Reach in 2015 and beyond RHIC & AGS Annual Users' Meeting 2011 2.76 TeV PbPb data (0.15/nb) b-jet 2013 5.02 TeV pPb data (35/nb) B meson b-jet 2015-17 5.1 TeV PbPb data (1.5/nb) B meson b-jet HL-LHC (10/nb): (b)-jet quenching at O(TeV) ttbar production … Stay tuned!

  36. RHIC & AGS Annual Users' Meeting • Backup slides

  37. Open heavy flavor production in pp collisions RHIC & AGS Annual Users' Meeting B+J/ψK+ Good agreement between POWHEG+PYTHIA and data

  38. B+ production in pp collisions at 7 TeV RHIC & AGS Annual Users' Meeting

  39. RHIC & AGS Annual Users' Meeting Supporting material for pp reference Data agrees with the FONLL expectation at 1.96(p-pbar, CDF) and 7 TeV(p-p, ATLAS,CMS) Expect the same agreement at 5TeV collision also CDF ATLAS, CMS Phys. Rev. D 75, 012010 (2007) arXiv: 1307.0126v2 39

  40. RHIC & AGS Annual Users' Meeting Summary of optimal cuts 40

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