Search for Charged Higgs in the Decay of Top Quarks at D0
Motivation
• A lot of time will be devoted to Standard Model Higgs searches.
• Need to look beyond the SM MSSM• h, H, H±, A.
Previous Searches at D0
• A search was done in the channel H± τ±ν– Counted events with hadronically decaying W. – Presence of a H± would cause a drop in different
channels (see Yvonne’s talk)• Similarly, H± cs was also investigated– Counted events with leptonically decaying W.
My Project
• So far I have been working on a method to improve the search for H± cs.
My Project
• Charged Higgs has spin 0, W has spin 1.• Should give rise to differences in kinematics of
the event, manifesting in different distributions for certain variables.
• Feed these discriminating variables into a neural network.
• Additionally, the mass of the charged Higgs is unknown so we can use different masses, giving rise to further discriminants
Discriminating Variables
- Angle between hadronically decaying boson and jet with 2nd highest pt
Discriminating Variables
Discriminating Variables
Discriminating Variables
Discriminating Variables
• Invariant mass of non-b jets
• For 120 & 150 GeV Higgs:– pt of SM b jets is harder– ht2 & ht3, again SM is a little harder– Eta, possibly (need to look with more events)
Looking Ahead
• Short term– Need to find a variable that discriminates well for
a charged Higgs of mass 80 GeV– Continue to implement the most up-to-date
Monte Carlo simulations– Look at reco. events
• Long(er) term– Separate signal from background by combining
variables with a neural network
Thanks
Terry, Christian & Yvonne