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Top physics at the

Top physics at the. LHeC workshop 20 th january 2014. Olaf Behnke (DESY). t. Single top production Top pair production. t. t. 1. Single T op production in charged currents. 5-flavour scheme. Determine V tb from cross section Check for anomalous production

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Top physics at the

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  1. Top physics at the LHeC workshop 20thjanuary 2014 Olaf Behnke (DESY) t • Single top production • Top pair production t t 1

  2. Single Top production in charged currents 5-flavour scheme • Determine Vtb from cross section • Check for anomalous production • Depending on (sensitive to) effective b-quark density in proton 2

  3. Single Top production in charged currents 5-flavour scheme • Determine Vtb from cross section • Check for anomalous production • Depending on (sensitive to) effective b-quark density in proton Can be determined in situ from F2bb measurements at LHeC ! 3

  4. Studies with Madgraph 5 generate e- p > ve t~ Madgraph parameters used throughout • Collider scenario: 7 TeV p on 60 GeV electrons • So far only on parton level • Standard madgraph cards (e.g. CTEQ6L1) • 5-flavour scheme 4

  5. Studies with Madgraph 5 generate e- p > ve t~ Obtained total LO Cross Section: 1.8 pb Check in the following slides the decay kinematics (is it within the LHeC detector?) 5

  6. Pt(b) Typical LHC cut (ATLAS, CMS) 6

  7. Pt(e) Typical LHC cut 7

  8. y(b) Typical LHC cut 8

  9. y(e) Typical LHC cut 9

  10. Conclusion from kinematic studies on charged current Single Top production • Majority of events is within the anticipated LHeC detector acceptance. 10

  11. CC Single Top at LHeC compared to LHC s-channel t-channel tW-channel tt prod. LHC 4.6 64.2 15.7 163 s @7TeV (pb) (NNLO Kidonakis) LHeC s (pb) (LO Madgraph) ~0.01 in DIS 1.8 0.0029 ~10000 2900 1.8M  Expected #events for 1000 fb-1 11

  12. CC Single Top at LHeC compared to LHC s-channel t-channel tW-channel tt prod. LHC 4.6 64.2 15.7 163 s @7TeV (pb) (NNLO Kidonakis) LHeC s (pb) (LO Madgraph) ~0.01 in DIS 1.8 0.0029 ~10000 2900 1.8M  Expected #events for 1000 fb-1 12 Available for precise Vtb determination

  13. CC Single Top: Status of Vtb at LHC GeorgioChiarelli, arXiv:1302.1773  Further detector level studies are needed to assess the LHeC potential for Vtb (Acceptance, Backgrounds from W production etc.) 13

  14. FCNC Anomalous Single Top production • Extremely suppressed in SM • Potential window to BSM Study by G. Brandt (LHeC 2008 workshop, Divonne) Using anotop MC with Kutg=0.01:  Expect for 7 TeV x 70 GeVLHeC with 1000 fb-1 7600 FCNC top events But large backgrounds from SM W and CC single top Better prospects at LHeC-based gp collider mode, see LHeC CDR, p.205 14

  15. FCNC single top – LHC results (2013) • Production studies: ATLAS 2.05 fb-1 CERN-PH-EP-2012-032 Kugt/L < 0.0069 TeV-1 Kcgt/L < 0.016 TeV-1 • Mostly decay studies: exploit BR(t qZ) ~ (KtqZ)2 KerimSuruliz Top 2013 workshop: Could LHeC with ~2M top quarks make sensitive decay studies? t  qZ not enough statistics, but perhaps t  qg (to be checked) 15

  16. Top pair production in DIS at LHeC • Sensitive to the proton gluon density at high x Madgraph LO Cross Section: 9.9 fb Expect more from photoproduction (not simulated yet) 16

  17. Top pair production in DIS at LHeC Kinematics Forward to very forward production 17

  18. Top pair production in DIS at LHeC Kinematics Corresponds to ~1500 fb-1 With L=1000 fb-1 expect some tens of events produced at high x >0.5 18

  19. Top pair production in DIS at LHeC Kinematics with final state cuts Corresponds to higher L t-> bln, t~-> bln pt(b)>10 GeV, pt(l)>10 GeV y(b)<3.0 y(l)<3.0 Total kinematic acceptance ~50%, high x somewhat suppressed 19

  20. Conclusions • Study top production for the first time at an ep collider  is a unique test of the SM • Single Top production in charged currents: Expect precision measurement of Vtb • Top Pair production in DIS and photoproduction: clean test of proton gluon density at high x(but suffers from rather low statistic) • In general: sensitive tests of new physics through anomalous production channels/cross sections and decays • Further studies at detector level needed (including background simulation) for detailed assessment of physics potential. 20

  21. Backup slides

  22. Top physics at the LHeC workshop 20thjanuary 2014 Olaf Behnke (DESY) • Single top production Wb t, gb  tW, FCNC gu t • Top pair production gg t t~ 1

  23. The Detector ‘that should do it’: Ring-Linac scenario Outer detectors (HAC tailcatcher/muon detectors not shown)also not shown: forward proton taggers, backward lumi monitors 20

  24. Missing ET X-sect=7.354E-01(pb) AVG=5.730E+01 RMS=2.992E+01 Tot#Evts= 21406Entries= 21402Undersc= 0Over 3

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