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Z0/ γ *( l + l - )+jet Made in LANL

Dilepton Tagged Jets via Angular Correlations. Z0/ γ *( l + l - )+jet Made in LANL. Paul Constantin, Gerd Kunde, Camelia Mironov. Made in LANL (with P. Constantin & G.J. Kunde). Camelia Mironov. S ignal B ackground M iscellaneous NEXT. Introduction Signal Background

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Z0/ γ *( l + l - )+jet Made in LANL

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  1. Dilepton Tagged JetsviaAngular Correlations Z0/γ*(l+l-)+jetMade in LANL Paul Constantin, Gerd Kunde, Camelia Mironov Made in LANL (with P. Constantin & G.J. Kunde) Camelia Mironov • Signal • Background • Miscellaneous • NEXT • Introduction • Signal • Background • Conclusions, applause, flowers etc.

  2. Azimuthal Correlations: h+h TriggerParticle Back side C(ΔΦ) Sameside Associated Particles BKG = B(1+2v2(pTasso)v2(pTtrig)cos(2)) CARTOON flow+jet A+A flow jet p+p hPt hadorn tagged (triggered) jet • p+p : z=pTassociated/pTtrigger Fragmentation function: • A+A: distribution of particles associated with a trigger aftermedium modification  have to disentangle the ‘jet’ component from the global ‘flow’

  3. Azimuthal Correlations: Z0/γ*+jet The DILEPTON is the tag BKG = B(1+2v2(pTasso)v2(pTtrig)cos(2)) no flow for dilepton flat global background • pTjet ~ pTZ0/γ* jet energy determined • no ambiguities (π0->2γ, η etc) like in γ+jet

  4. Theory: γ+jet z = pT/pjet  Wang, Huang, Sarcevic PRL 77, 231 (1996)  Wang, Huang PRC 55, 3047 (1997) •  measure D(z) in pp and AA • λa (parton inelastic scattering mean free path)  dEa/dx (parton energy loss)  Arleo et al (hep-ph/0410088), Arleo(hep-ph/0601075): γ-π0 and γ-γ correlations  medium modified fragmentation functions Energy loss models (GLV, BDMS etc) connect partonic energy loss to fundamental properties of the medium – gluon density, system size etc

  5. PYTHIA Signal at LHC =5.5TeV PYTHIA v6.326 Mass_γ* >12GeV (default) |η| <3.0

  6. PYTHIA Signal at LHC =5.5TeV ~NUMBERS: Luminosity = 0.5 (mbs)-1 Run time = 106 (s) (2 weeks) Z(pT>50 GeV/c) ~790

  7. Cross-check for the PYTHIA number … Campbell and Maltoni: cross sections at NLO == MCFM (http://mcfm.fnal.gov) BR*Lumi*runTime*A^2 ~720 Z0 with pT>50GeV/c

  8. PYTHIA Z0 Signal ΔΦ vs pTdilepton z=pThadron/pTdilepton z vs pTdilepton

  9. Background | | | | | | | | | | | |__| | | |__ ____ | |_____ Heavy quarks and their semi-leptonic decay channels BR(B --> lxy) ≈ 10.2% BR(D --> lxy) ≈ 6.7%

  10. Signal & Background : Theory Gale, Srivastava,Awes nucle-th/0212081

  11. Understanding background: theory CERN yellow report on heavy flavor production: hep-ph/0311048 NLO (HVQMNR) (Mangano, Nason, Ridolfi hep-th/xxxxx) PYTHIA total

  12. My MNR: ΔΦ(ccbar) Distribution ccbar: independent trend in ΔΦ with increasing the momentum pT(ccbar)>20GeV/c Pt(ccbar)>150GeV/c

  13. My MNR: ΔΦ(bbbar) Distribution bbbar: change in ΔΦ when increasing the momentum cut pT(bbbar)>20GeV/c pT(bbbar)>150GeV/c

  14. Reduce Background plepton pmeson vtx (0,0,0) lepton = e±, μ± meson = D±, B± dca …understand background first!!  comon sense: DCA cut on displaced lepton track Profile histogram (value=mean, bars=rms) 3<plepton<5 GeV/c 5<plepton<7 GeV/c 7<plepton<10 GeV/c 10<plepton<13 GeV/c Dca(mm)

  15. Reduce background: DCA  If we assume a dca resolution in σrφ~20μm and σz~50μm Statistical error bars • can identify (reject) ~80% of the heavy background • pT dependent trend?

  16. Before the end … • Use a weakly interacting probe (Z0/γ*(l+l-)+jet) to tackle the properties of a strong interacting medium  weak is good (this time) • Advantages over ‘traditional’ h-h, γ-h analyses: no flow, no high pT limit etc. • ‘Smallish’ rates  you can’t have everything (rates, high pT reach and purity) in life La vita seems to be bella nevertheless …

  17. The End

  18. Z0/γ* - jet γ*/Z0 γ*/Z0 γ*/Z0 γ*/Z0 Initial state radiation · Σ(pT_incomingPartons)!=0  pTjet !=pTdilepton • Final state radiation • It will broden the jet distribution

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