Higgs to ZZ(*) at Generator Level Study

Detailed Description

I want you to educate me on the kinematic properties of Higgs produced via gluon fusion at a 14TeV proton proton collider, i.e. the LHC, and decaying into ZZ*.

In particular, you should use Pythia, possibly straight from within root, i.e. as TPythia, to produce Higgs via this process at two masses (130GeV and 150GeV), and have it decay into ZZ*.

I suggest you start by learning how to generate a sample at generator level using Pythia is cmssw to generate Higs to ZZ*, and to decay the Z's generically. Then learn how to use root to look at the generator level quantities, and produce a branching fraction table like the one I produced in my talk below.

Next, I want you to plot the di-lepton invariant mass at generator level for ee, mumu, and emu, and explain the differences between the three.

Next, compare the ee invariant mass distribution for the 130GeV and 150GeV samples. Explain what you see.

Next, select a sample of Higgs decays for which the Z* decays into di-leptons, and plot a 2d scatter plot of the two lepton transverse momenta. Select the Z* only based on the di-lepton invariant mass, not the generator information. Use this plot to determine the trigger efficiencies for the lepton trigger lines as mentioned in my talk. Make up the trigger simply based on transverse momentum and eta cuts. Do so for both the 130GeV and 150GeV sample.

Finally, study (and plot) the kinematic quantities, and compare the 130GeV and 150GeV higgs mass cases. I'm particularly interested in:

• transverse momentum of the Higgs
• transverse momentum of the Z, and Z* (2D scatter plot).
• mass of the Z and Z* (2D scatter plot)

That's enough for a start. Once you are done with this, we'll look at Higgs to ZZ above the ZZ threshold, i.e. for the case where both Z are on-shell (real rather than one of them being virtual). We will in particular look at the 2 tau 2 mu final state.

-- FkW - 27 Jun 2006

• higgs-June-21-2006.ppt: This is the power point of the presentation I gave you at our meeting.