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

Back up

Link to B jets (old MC)