FCC-ee physics zoom meeting -

Monday 26 Apr 2021, 15:00 → 17:45 Europe/Zurich

Christos Leonidopoulos (The University of Edinburgh (GB)), Matthew Philip Mccullough (CERN)

Topic: General Monthly FCC-ee physics meeting

Minutes of 26-Apr-21 FCC physics meeting
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Agenda: https://indico.cern.ch/event/1019437/

(1) News, Q&A, general discussion (Alain Blondel)
Slides: https://indico.cern.ch/event/1019437/contributions/4278605/attachments/2233202/3784500/AB-PJ-news.pdf

ECFA Detectors Experiments and Physics Workshops

Three working groups defined and conveners agreed for WG 1 and 2.
Group 1, Physics Potential: Juan Alcaraz, Jenny List, Fabio Maltoni and James Wells
Group 2, Physics Analysis Methods : Patrizia Azzi, Dirk Zerwas, Fulvio Piccinini
Group 3 Detectors (pending ECFA road map completion)

Next workshops scheduled:
Task Force 1: Gaseous Detectors: 29 April
Task Force 9: Training: 30 April
Task Force 4: Photon Detectors and Particle Identification Detectors: 6 May
Task Force 6: Calorimetry: 7 May

FCC sw news: LEP data being migrated into EDH4hep format

Events of FCC interest:
0. FCC-nordic meeting took place March 22
1. Next FCC week: 28 June – 2 July
2. Νext FCC-France workshop Annecy: 30 Nov to 2 Dec. In person???
3. Next FCC-PED workshop (all FCC flavours): Liverpool February 2022

(2) Untangling the spin of a dark boson in Z decays (Emidio Gabrielli)
Slides: https://indico.cern.ch/event/1019437/contributions/4329713/attachments/2233234/3784546/Talk_CERN-FCC-ee-physics-EG.pdf

Z --> gamma + X, X: light long-lived dark (invisible) boson

Main signature: monochromatic photon + missing energy

Potential scenarios:
- spin-1 Dark Photon: massless case allowed by LY theorem
- massive spin-0 ALP (axion-like particles)
- massive spin-2 particles (KK gravitons, composite spin-2, etc)

Best place to search for this signature in high-lumi e+e- colliders (FCC: 10^13 Z boons)

Different photon-angular distributions: spin-1 vs spin-0/2
(spin-2 can be disentangled from spin-0 only for large spin-2 masses)

Matthew McCullough: Is the EFT for spin-2 definitely valid for small masses.
Answer: Yes.

Roy Aleksan: left plot on pg. 25, why is the photon non-monochromatic
Answer: This is due to detector resolution

(3) Jet clustering interface in FCC Analyses & b-tagging (Julie Munch Tornda)
Slides: https://indico.cern.ch/event/1019437/contributions/4329732/attachments/2233233/3784547/JetClustering_and_bTagging.pdf

Motivation: physics analysis of t-tbar events in semileptonic channel at FCCeee

Development of just clustering interface in (sw package) FCCAnalyses (on github). Can run multiple jet reconstructions in one go.

Jet definition uses a combination of algorithm and recombination scheme.

Next steps:
b-tagging a la Delphes: start with a jet, look for a b-parton within Delta-R < 0.3
b-tagging using b-hadron decay products
b-tagging with vertexing

This is still work in progress, expect more updates to be reported at future Physics Performance meetings.
 

15:00 → 15:20 News, Q&A and general discussion

Speakers: Alain Blondel (Universite de Geneve (CH)), Patrick Janot (CERN)

AB-PJ-news.pdf

AB-PJ-news.pptx

15:20 → 15:50 Untangling the spin of a dark boson in Z decays

Speaker: Dr Emidio Gabrielli (Nat. Inst. of Chem.Phys. & Biophys. (EE))

Talk_CERN-FCC-ee-physics-EG.pdf

15:50 → 16:10 Jet clustering interface in FCC Analyses & b-tagging

Speakers: Julie Munch Torndal (University of Copenhagen (DK)), Julie Munch Torndal (CERN)

JetClustering_and_bTagging.pdf