FCCee Top Physics Meeting

mercredi 6 avr. 2022, 15:00 → 18:00 Europe/Paris

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

1 Introduction

Orateur: Romain Madar (Laboratoire de Physique Corpusculaire de Clermont-Ferrand (LPC))

2 Update on event generation with Whizard

Orateur: Laetitia Guerry

FCC.pdf

3 Update EFT and FCCee samples

Orateur: Lars Röhrig

meeting.pdf

4 Update on PDF sampling methods

Orateur: Athina Monemvassitis

athina.pdf