1. Michael Carrigan Advisors: Kevin Black & Lidia Dell’Asta
T-Prime Study Update
Michael Carrigan
Advisors: Kevin Black
&
Lidia Dell’Asta

2. Reminder
I am using Monte Carlo simulated data to look for the signal of the T-Prime vector like quark (VLQ)
Background is generated with center of mass energy 33TeV
Signal is generated from 33TeV as well with a mass of 500 GeV and no pile up
Looking at the T’-> tH decay b q W- g T’ H t W l ν

3. Roadblock 33 TeV background files are currently unavailable
Owned by CMS and stored at Fermilab
Currently working to get access to more than a few files
In the mean time I have been working with ~3.5 million events on the BU SCC
Backgrounds are BB, BBB, tB, ttB, tt
All have 0 pile up and are generated with 33 TeV center of mass energy

4. Efficiency of Cuts
Need to ensure the cuts we are making save as much signal as possible and eliminate as much background as possible
Looking at efficiency as S’/√B’
S’ = εS * cross section * integrated luminosity
B’ = εB * cross section * integrated luminosity
ε = # of events before / # of events after

5. Efficiency of Cuts Decided that the most efficient cuts for:
MET = 25 GeV
HT = 600 GeV
However our efficiency was still too low ≈
Looking for ways to improve the number of signal events kept

6. Signal Masses Before I was using a signal with a mass of 500 GeV
Added in signal data with masses 1000, 1500, 2000, GeV
This means the T-prime particle was simulated with these five different masses
In general the efficiencies dropped for the greater masses

7. Number of b-jets
The theory for T’ -> tH predicts that there will be 3 b-jets produced
But after the b-jet cut we went from 80-90% of events to 1- 2% b q W- g T’ H t W l ν

8. Changing the b-jet Cut
Decided to try requiring only 2 b-jets to allow for one jet being missed by the detector
But the efficiency dropped lower -> need to keep the 3 b-jet requirement

9. Next Cut?
Unfortunately the list of cuts doesn’t allow for many other changes

10. Ideas?
Looking at the T’->tH decay but we have only looked at the decay that creates a Higgs that decays as H-> bb
This is the most likely Higgs decay but not the only one we can look at

11. Higgs Decays

12. Next Steps
While we wait for the background monte carlo samples I will be looking at different Higgs decays to see if there is a more efficient decay
Most likely looking at H->gg
Need a decay with a large branching ratio as well as decay products that are easy to see in ATLAS