Zg2 j3 bkg generation for VBF Higgs A

Z/g*+2 j(3) bkg generation for VBF Higgs A. Nikitenko in collaboration with ALPGEN team (F. Piccinini and M. Mangano)

Jet veto in VBF (WW->H) production first discussed in : Yu. Dokshitzer, V. Khoze and S. Troyan, Sov. J. Nucl. Phys. 46 (1987) 712 Yu. Dokshitzer, V. Khoze and T. Sjostrand, Phys. Lett. , B 274 (1992) 116 From D. Zeppenfeld talk on Te. V 4 LHC, 2004

Correct generation of 3 rd jet for jet veto • Generate z/g*+2 j and z/g*+3 j with ALPGEN and VBF soft pre-selections at parton level – |Dhj 1 j 2 |> 4. 0, Mj 1 j 2 > 600 Ge. V (program zjetusr. F) j 1, j 2 – two highest p. T partons – p. Tj > 20 Ge. V, |hj |< 5. 0, Drjj > 0. 5, Mll > 70 Ge. V – Ickkw 1 (needed for ME+PS) • ME+PS matching to avoid double counting with MLM prescription. PYTHIA code is under final tests by MLM. • Produce CMKIN ntuples after ME+PS, fetch into production

Parton p. T ALPGEN Z+2 j ALPGEN Z+3 j

Parton h ALPGEN Z+2 j ALPGEN Z+3 j

“Reco” jet h, PYTHIA jets (PYCELL, cone 0. 5) ALPGEN+PYTHIA Z+2 J ALPGEN+PYTHIA Z+3 J

“Zeppenfeld plot” (I) ho=hj 3 -0. 5(hj 1+hj 2) same p. T cut on tag jets and j 3 Tevatron W+2(3)J MC , Dhj 1 j 2 > 2. 0 shown by J. Huston in Les Houches LHC Z+2(3)j MC , Dhj 1 j 2 > 4. 0

“Zeppenfeld plot” (I) ho=hj 3 -0. 5(hj 1+hj 2) p. T cut on tag jets is higher that on j 3 Tevatron W+2(3)J MC , Dhj 1 j 2 > 2. 0 shown by J. Huston in Les Houches LHC Z+2(3)j MC , Dhj 1 j 2 > 4. 0

“Zeppenfeld plot” (I) ho=hj 3 -0. 5(hj 1+hj 2) increase p. T cut on both tag jets and j 3 Tevatron W+2(3)J MC , Dhj 1 j 2 > 2. 0 shown by J. Huston in Les Houches LHC Z+2(3)j MC , Dhj 1 j 2 > 4. 0

outline • Correct generation Z+2 j and Z+3 j with VBF soft preselections started with test version of ALPGEN for ME+PS • Intermediate plots, distributions look reasonable. Un-weighting efficiency is ~ 1 K events on 100 M • Next step ME+PS will be made with PYTHIA code under preparation by MLM.