H->bbbar Final State Subgroup (LHC HXS WG)

Contribute to Sharepoint discussions here: VH production, ttH production, bb final state.

Group Contacts and Contributors

• ATLAC/CMS/LHCb Contacts: Chris Potter (Oregon)/Jim Olsen (Princeton)/Clara Matteuzzi (Milano-Bicocca)
• Experiment: Chris Potter, Jim Olsen, Clara Matteuzzi, Chris Neu, Chris Collins-Tooth, Giacinto Piaquadio, Douglas Wright, Michiel Sanders, Ben Smart, Andrea Messina
• Theory: Laura Reina, Michael Spira

All contributors are welcome!

Meeting Agendae

• February 2011
• March 2011
• May 2011

Plan of Activity

• VH->Vbb differential K-factor (LO to NLO) in signal and background after common cuts with MC@NLO and POWHEG
• ttH->ttbb differential K-factor (LO to NLO) in signal with aMC@NLO
• evaluation of VH->Vbb and ttH->ttbb cross section uncertainties at NLO after common cuts

Common cuts definition between CMS/ATLAS/LHCb

VH->Vbb for LHCb

Boosted VH->Vbb (PRELIMINARY!)

• pt(H)>200 GeV
• pt(V)>200 GeV
• No additional C/A jets with pt > 20 GeV (|eta|<2.4)

Non-boosted VH->Vbb (PRELIMINARY proposal from ATLAS, to be discussed with CMS and LHCb)

• pT(e/mu) > 20-25GeV
• |eta(e/mu)| < 2.5
• 2 jets with pT>25GeV
• MET > 25GeV (????)

ttH->ttbb (PRELIMINARY!)

• exactly one isolated lepton with pt>25 GeV (20 GeV) e(mu).
• >=6 jets with pt>20 GeV
• >=4 b-tagged jets with pt>20 GeV

Baseline Common Parameters

arXiv:1101.0538

CERN-2011-002

Parameter	arXiv:1101.0538 Choice
alpha_s	0.118, 0.1207, 0.119 resp.
delta alpha_s	0.002 90% C.L.
NLO PDF	CTEQ6.6, MSTW2008, NNPDF2.0

Parameter	CERN-2011-002 Choice
electron mass	0.510998910(13) MeV
muon mass	105.658367(4) MeV
tau mass	1776.84(17) MeV
u quark mass	190 MeV
d quark mass	190 MeV
s quark mass	190 MeV
c quark mass	1.40 GeV
b quark mass	4.75 GeV
t quark mass	172.5 ± 2.5 GeV
MS scheme c mass	1.28 GeV
MS scheme b mass	4.16 GeV
c pole mass 1-loop	1.41 GeV
c pole mass 2-loop	1.55 GeV
b pole mass 1-loop	4.49 GeV
b pole mass 2-loop	4.69 GeV
W mass	80.398 ± 0.025 GeV
W width	2.141 ± 0.041 GeV
NLO W width	2.08872 GeV
Z mass	91.1876 ± 0.0021 GeV
Z width	2.4952 ± 0.0023 GeV
NLO Z width	2.49595 GeV
GF	1.16637(1) × 10−5 GeV−2

Available Tools

• MC@NLO
• POWHEG Box
  • The Wbb Process in POWHEG (NLO)
• aMC@NLO
  • ttH in aMC@NLO (contact the authors at amcatnlo@cernNOSPAMPLEASE.ch).

Results

References

• ATLAS Sensitivity to the Standard Model Higgs in the HW and HZ Channels at High Transverse Momenta ATL-PHYS-PUB-2009-088
• Search for ttH->ttbb CERN-OPEN-2008-020 (pp. 1333-1363)
• Search for H->bb in Association with a ttbar Pair at CMS CMS-NOTE-2006-119
• PDF4LHC Working Group Interim Recommendations arXiv:1101.0538
• Handbook of LHC Higgs Cross Sections: 1. Inclusive Observables CERN-2011-002

-- ReiTanaka - 02-Oct-2010