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H -> ZZ* Process

Goal of the group

Group Contacts

Group Members

  • Experiment: Chiara Mariotti, Cristina Botta (Torino), Gurpreet Singh Chahal (Bari)
  • Theory: Everybody who wants to contribute

Plan of the Activity (both Higgs signals and SM backgrounds)

  • differential K-factor
  • overview of background determination methods (data-driven, non-data driven)
a) sidebands by extrapolating the bkg from a control region (measured with data) to a signal region by the MC prediction 
b) ABCD method:  definition A,B,C,D control region based on two observables (isolation, impact parameter, for example for Zbb evaluation).
Strategies for the evaluation of ZZ and Zbb already defined but the results need to be compared if using NLO monte carlo instead of LO. 

  • list of LO/NLO Monte Carlo's
CMS: is going to produce PYHIA6 and POWHEG+ PYTHIA6; as soon as samples are available we will compare the main kinematical distribution LO vs NLO. Evaluation of cross section with POWHEG
is on going.  I started to play by myself with POWGEG (with the help of pietro govoni) to evaluate the differential k factor.  Hope to provide results soon. 
ATLAS:  need to check asap with stathes
  • wish List for theorists

Common cuts definition between ATLAS and CMS

  • 4l final state:
* leptons with |eta|<2.5
* >=3 leptons with pT>5
* >= 2 leptons with pT>10
* (eventual criteria on identification and isolation of electrons could be used for keeping the rate of background controlled)
*At least two l+l- pairs of identified leptons with opposite charge and matching flavour. Electrons are required to satisfy pT>5 in |eta|<2.5 while 
muons are required to satisfy pT>5 in the barrel (|eta|<1.2        and pT>3 + p>9 in the endcap (1.2<|eta|<2.4). 
* at least two matching di-lepton pairs with m2l>12 GeV
* at least one 4-lepton combination with m4l>100 GeV

* >=4 leptons with PT>5GeV
*  >=2 leptons with PT>20GeV
* l=&#956;: |eta|<2.5 and 2.5<|eta|<2.7
* l=e: |eta|<2.47
* Delta R_ll>0.1
* Lepton Isolation criteria (theoretically complicated)
* l=&#956;: Sum ET(Delta R=0.3)/PT_l<0.33
* l=e: Sum ET(Delta R=0.3)/PT_l<0.44
* 70GeV<M_12<110GeV; leading two same flavor, opposite charge, lepton pair
* M_34>20GeV for M_H<200GeV and 70<M_34<110GeV for M_H>=200GeV
* |m_12-m_z|<cut_m12 (see the table below)
* For MH<200GeV: m_34>cut_m34 (see the table below)
* For MH>=200GeV, |m_34-m_z|<cut_m34 (see the table below)

  • 2l2nu:
  • 2l2b:

Available Tools





-- ReiTanaka - 02-Oct-2010

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Topic revision: r2 - 2010-10-11 - NicolaDeFilippis
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