Muon Collider Full Simulation Studies

~slomte/mucol on pages.hep.wisc.edu

[parent]
DESCRIPTION:

We look at single Higgs production at a muon collider focussing on bottom quark anti-quark decay of the Higgs particle.
Process: mu- mu+ ---> H v v with H ---> b b at center of mass energy of 1.5 TeV.
This event is overlaid with beam-induced background (BIB) originating from muon decay with 750 GeV beams.
We study the reconstruction performance of b-jets in the event without and with the presence of BIB. Plots below show kinematic features of single Higgs process with 10k simulated events.
The configuration files can be found here: link
The analysis script can be found here: link
Working directory is here: login.hep.wisc.edu:/nfs_scratch/slomte/MuColl/runjobs10bib/singleHiggs/bib100/analysis/

Algorithm for jet clustering: anti-KT with cone size of 0.5.
Some definitions:
'good' jet is jet with PT>10 GeV and 10 < \theta < 170 (accounting for nozzle structure), we abbreviate this as gj = good jet.
'matched' jet is reco jet with a gen jet in delta_R=0.5, if more than one is present, min delta_R is chosen. We abbreviate this as mj = matched jet.
mgj = matched good jet.

Jet Energy Correction Scheme:
For reasonable runtime with 100% BIB, we have Energy and Timing cuts on reco hits in Calorimeter. The reco jets lose energy due to these E and T cuts. To recover some of this energy, we use jet energy correction scheme.
Choose regions with |eta|:[0,0.5], [0.5,1], [1,2.5] and PT: [10,50], [50,100], [100+]
For gen jets in these regions, define scale factor = genjet.PT / recojet.PT where reco jets are without BIB presence. Find average and std dev for these scale factors in total of 10k events. Then apply this scale factor to reco jets in signal+BIB event. For gen jets in these regions, we find matched reco jet in minimum delta_R, and multiply its 4-vector by the scalar factor. We call these jets as corrected jets ( abbreviated as 'cmgrj' = corrected matched good reco jets).

Invariant mass (M_bb) is computed using the two leading jets (in PT) in event.

Key points:
- matching scheme reduces fake jets (by construction), but need to do better.
- acceptance selection reduces fake jets and cen be made tighter.

[June 6] Next steps:
- Use AK7 jets (instead of AK5) to reconstruct higher jet energy.
- Use BIB mitigation strategy to reduce M_bb close to 125GeV.