FCCee Top Physics Meeting
1st floor meeting room
Zoom meeting
link: https://cern.zoom.us/j/61529347696?pwd=cGRFUHVrcHNGRjJTNG1xc0pZNWVYUT09
Meeting ID: 615 2934 7696
Passcode: 1234
Notes on FCCee Top Physics Meeting, 06.04.2022
Participants: L. Guerry, A. Monemvassitis, S. Monteil, R. Madar, L. Roehrig
Next meeting: tba
- Laetitia's studies:
- Solved issue of discontinuity at 340 GeV
- m_t = 172 GeV fits the CDR studies better, although it uses m_t = 171.5 GeV
- Before threshold (sqrt(s) = 335 GeV, e+ e- > b W b W): Real and virtual tops (build from decay products) differ in kinematics -> Why is there a dip at m_t in the energy distribution?
- Energy distribution not symmetrical due to beam effects?
- b & W distributions have reasonable shapes
- Top angular distributions show effects of forward-backward asymmetry -> Largest at higher energies (sqrt(s) ~ 400 GeV)
- Comparison between MG & whizard: Very similar shapes but whizard seems to handle top energy better around the threshold: less uncertainty
- Beam effects mainly arise in the tails of the distributions
- Lars's studies:
- Focus on object reconstruction, mainly W bosons in the semileptonic channel
- Clear signature: 1 lepton (e or µ), MET, 4 jets (2 of them b-tagged (j_b))
- Leptonic W boson has sharp peak around m_W
- Hadronic W boson
- m_{j_nb + j_nb}: broad distribution, no clear peak around m_W
- Loose b jet requirement and build W from the jets with minimal distance to m_W: sharp peak around m_W
- Reconstructed top-quarks have similar shapes due to W-boson distributions
-> Get in contact with Julie Torndal (did top-quark studies at FCCee)
- Athina's studies:
- First tests to sample the EFT likelihood with the discrete PDMP algorithm in 3 dimensions
- Cross-check: parameterisations of the observables as function of the C_i's match the ones in the paper
- Sampling one coefficient onto one observable works good -> distributions look similar
- Sampling of more coefficients at a time for one observable more challenging but good agreement, except C_uB marginal distribution with BR-measurement
- Use hard bounds on C_i range, similar to Uniform distributions between [-1, 1]
- Future meeting beginning of next week planned to directly use discrete PDMP (implemented in BAT.jl) in the EFTfitter framework -> better comparison, already in contact with Cornelius