dubna03

On the possibility to observe with CMS a moderately heavy Higgs decaying via HZZllnn: 

On the possibility to observe with CMS a moderately heavy Higgs decaying via HZZllnn Leonid G. Levchuk Kharkov Institute of Physics andamp; Technology

Motivation: 

Motivation Search for physics suggesting importance of hadron calorimetry HZZllnn has ~6 times greater BR compared to HZZ4l Some light could be shed on physics of ZZ interaction

Previous studies: 

Previous studies N.Stepanov, CMS-TN/93-087 (1993); N.Stepanov and S.Abdullin, CMS-TN/94-178 (1994); I.Gaines, D.Green, S.Kunori, J.Marrafino, J.Womersley, and W.Wu, CMS-TN/95-84 (1995)  heavy (MHandgt;500 GeV) Higgs observability via HZZll was studied; irreducible background (IB) due to ZZ/ZW production thwarts H observation L.Levchuk, 6th annual RDMS CMS collaboration meeting (MSU, Moscow, 2001); L.Levchuk, D.Soroka, P.Sorokin, V.Trubnikov, and S.Zub, 7th annual RDMS CMS collaboration meeting (IHEP, Protvino, 2002) extension to MH=200250 GeV; ways to eliminate IB

Simulation tools: 

Simulation tools PYTHIA (Ver. 6.158) CMSJET (Ver. 4.703) Z+jets ZZ ZW Background contributions irreducible background

Slide5: 

1-st level ('tentative') cuts: ETmiss andgt; 60 GeV, 2 leptons such that : |l| andlt; 2.4, pTl andgt;20 GeV, PTll andgt; 40 GeV, |MZ-Mll| andlt; 5 GeV At threshold of HZZ decay, (MTZZ  2MZ)1/2  | |

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'Loose' cuts ('A') 1-st level ('tentative') cuts: ETmiss andgt; 60 GeV, 2 leptons such that : |l| andlt; 2.4, pTl andgt;20 GeV, PTll andgt; 40 GeV, |MZ-Mll| andlt; 5 GeV Elimination of the IB: No b-jets: Nb-jets=0

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'Hard' cuts ('C') 1-st level ('tentative') cuts with loosed cut on ETmiss : ETmiss andgt; 40 GeV, 2 leptons such that : |l| andlt; 2.4, pTl andgt;20 GeV, PTll andgt; 40 GeV, |MZ-Mll| andlt; 5 GeV Elimination of the IB: No b-jets: Nb-jets=0 Extra criteria (I): Extra criterion (II) – selection of single-jet events: Nj=1 , 1.0andlt;|j| andlt; 4.5, pTj andgt;40 GeV

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Current status and plans for nearest future: 

Current status and plans for nearest future Publication of the preliminary results L.G.Levchuk, P.V.Sorokin and S.Kunori, 'On the possibility to observe a heavy Higgs via HZZll decays at CMS', CMS Note (or CMS_IN?) – in preparation Search with 'fast' MC for kinematical criteria providing a better signal/background ratio In case of success, preparation for 'detailed' (OSCAR or CMSIM) simulation andamp; ORCA reconstruction Check for reliability and degree of the IB suppression Simulations with a generator other than PYTHIA (HERWIG, …?) Simulations of the non-resonant ZZ/ZW production accompanied by high-pT jets based on 23 hard processes (COMPHEP, …?) NLO calculations of the non-resonant ZZ/ZW production (MC@NLO_2.2 [http://www.hep.phy.cam.ac.uk/theory/webber/MCatNLO], …? ) Consideration of the 23 Higgs production A generator for a combined treatment for both WBF and QCD 23 mechanisms of Higgs production – under development