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FCC-ee physics zoom meeting -
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Description
Topic: General Monthly FCC-ee physics meeting
Videoconference
FCC-ee physics zoom meeting -
- Zoom Meeting ID
- 61840768429
- Host
- Christos Leonidopoulos
- Useful links
- Join via phone
- Zoom URL
-
Minutes of 29-Mar-21 FCC physics meeting
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Agenda: https://indico.cern.ch/event/1019436/
(1) Patrick Janot, News
Slides: https://indico.cern.ch/event/1019436/contributions/4278604/attachments/2217192/3754519/News_GeneralMeeting_29Mar2021.pdf
* ECFA Detector R&R roadmap:
Several sessions taking place these days discussing R&D and plans
3 working groups: Physics potential, physics analysis methods, and detectors
IAC meeting on 1st April to discuss start-up activities
* PED coordination meeting:
Decision to create a task force to work on the organisation of the Detector Concepts effort (chaired by Mogens Dam)
People wanting to work on FCC can become CERN users by signing FCC MoU form (see slides for details/links)
Proposal to migrate LEP data to EDM4help format to allow PhD students to work with real-collision data in FCC SW environment
Next FCC Week: 28 June to 2 July
Accelerator Study: FCCee calls for four interaction points
Upcoming meetings:
- 7 April (TBD): Detector Concept organisation & mandate
- 15 April: FCC PED coordination meeting
- 19-21 April: FCCee reviews
(2) Chang-Yuan Yao, Searching for heavy neutrinos with tau leptons at future hadron colliders
Slides: https://indico.cern.ch/event/1019436/contributions/4295002/attachments/2217701/3754800/FCChh_HeavyNeutrino.pdf
Lepton number violation at colliders can be probed by U(1) extension of canonical Type-I Seesaw
Flavoured U(1) [B-L]3: weaker experimental constraints
HL-LHC: heavy neutrinos accessible, but not at 5-sigma level
FCChh: LNV signal with tau leptons accessible up to 3 TeV with g' = 0.6 and 30 ab^-1
Discussion
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Patrizia Azzi: could FCCee detect some propagator effects involving Z'
Answer: in this model the Z' can only be produced via b-bquark and decay into tau lepton pairs
Arindam Das: Results shown are from 2015 paper. However, ATLAS has now published newer data (from 2019).
Answer: Only looking at tau channel here, assuming no mixing
Alain Blondel: Sensitivity to heavy Dirac neutrinos?
Answer: This would be a different model, but worth investigating
(3) Andre De Gouve, Can we tell if an HNL discovered in Z decay is a Majorana or Dirac particle?
Slides: https://indico.cern.ch/event/1019436/contributions/4295003/attachments/2217672/3754746/FCCee_Z_decay-Andre-de-Gouvea.pdf
Non-zero neutrino masses imply the existence of new degrees of freedom. These could show up at collider experiments as long as they are not too heavy. May be very weakly coupled.
Definition: heavy neutrinos couple to the W and the Z through their mixing with the SM lepton. Q to ask: do they have anything to do with generating the neutrino masses?
Very difficult to assess whether massless neutrinos are Majorana or Dirac.
Can either:
- Look for phenomena implying Majorana neutrino
- Work with non-ultra-relativistic neutrinos
Majorana & Dirac heavy neutrinos produced differently in e+e- -> heavy-plus-light neutrino pairs.
Angular and energy distributions different enough to do hypothesis testing.
Discussion
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Matthew McCullough: influence on detector design, e.g. specs on angular resolutions etc?
Answer: Direction of heavy neutrino is main priority; Charge of the charged lepton also very important
Alain Blondel: If lifetime of neutrino is short, not possible to measure the direction
Christos Leonidopoulos: any comment about LRSM that requires introduction of right-handed W?
Answer: Only discussing extension of SM to include heavy neutrinos that does not require a new interaction
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