Searches for Long-Lived Particles

Wednesday 14 Oct 2020, 15:00 → 16:00 Europe/Zurich

Zoom (CERN)

Rebeca Gonzalez Suarez (Uppsala University (SE))

This meeting will happen in Zoom:

https://uu-se.zoom.us/j/65021247627

Meeting ID: 650 2124 7627

 

Connected:
Alain Blondel, Patrizia Azzi, Arindam Das, Elena Graverini, Marco Drewes, Oleg Ruchayski, Valentina Diolaiti, Emmanuel Perez, Rebeca Gonzalez Suarez

### Round table and Presentation
Proposed questions:
- ex/th/pheno
- prior experience: LLP, FCC-ee?
- Interested in?
- Any other thing?

Valentina
- master student working on master thesis
- Muon system FCC-ee, and validating FastSim delphes
- Interested in using madgraph and delphes with IDEA

Oleg
- Professor, 15 years experience with HNL, SHiP, ATLAS
- FCC-ee experience supervising master theses

Patrizia
- FCC-ee vast experience, working with Emmanuel leading Physics Performance studies
- Interest in detector requirement studies, recostruction algo development...

Marco (and Jan Hajer)
- Theorist, Belgium
- Early universe cosmologist, interest in searches for LLP at colliders
- HNL experience (several papers)

Juliette
- CMS, new CERN fellow
- Extensive LLP experience (displaced leptons, stopped particles, heavy stabled charged particles)
- new to FCC

Emmanuel
- working with Patrizia (see above) connected to FCC for a long time
- attending the meeting to see how this group starts
- Exo experience  

Elena
- Experimentalist, Postdoc at EPFL
- Sterile neutrinos (first to study them in an FCC context)
- SHiP and LHCb

Arindam
- Theory, different models (seesaw) LHC and ILC
- RHN interest

Alain
- Working on FCC-ee since 2011/2012
- 2012: HNL reach at the FCC-ee, motivation for a high lumi Z run  
- Organization of the physics groups ongoing, this meeting will hopefully provide a paper for the Snowmass, and will help covering experimental part.

Rebeca
- ATLAS/CMS
- Interest mostly LLP with respect to hardware/tracking/trigger

Patrizia then goes through the slides that are attached in the indico agenda, which contain an introduction of the LoI and the potential next steps.

### Discussion

Q: (Elena) is there a collection of stata-of-the art material on LLP for the LLP-ee?
A: (Patrizia, Rebeca) there is no official, in the LoI the main trends are summarized, but it would be a good starting point for this forum to index them in a systematic way.
Follow-up offline

Q: (Elena) FCC-ee official working group?
A: (Alain) no, we have not been systematic in categorizing these studies yet. Small discussion happened on different studies.
A possibility to start the work of the group is to complete a table of possible benchmarks.
(Patrizia) the Physics group of the FCC-ee is not very large and we see here a significant critical mass that we can make into a working group.
It is important to know asap what are people favorite topics.

Q: (Alain) one of the goals of this meeting is to discuss what we can put in the agenda for the next meeting, Marco you think it is possible to produce a list of benchmarks?
A: Discussion on this being a good starting point
Elena says there is enough HNL literature already, and it will be good to see what else is there
Marcin (not connected), has some plans, will be invited to the next meeting specifically.
Matthew can be invited to prepare a list of refeences.

Q: (Elena) we need effort on experimental side for improving HNL, see e.g. until where you can reconstruct a vertex
A: agreement

Q: (Elena) status of the simulation/tools for FCC-ee?
A: (Patrizia) for full sim there are two concepts CLD (from CLIC experience) and there is the IDEA (in Geant)
There are some tools but maybe they are not developed enough to be used by undergrad students for example.
Proposal to keep the info on code and tools somehwere (next meeting?)

Q: (Marco) How about the detector design? some interesting unique concepts where discussed sometimes, what is the status?
A: (Alain) Discussion. Something like FASER is not what we want, we want to put things close to the vertex, we could have large detectors (15 m radius) by using the space of the hadron collider detectors in the caverns (very long detector for example) (it needs to be cheap) ()keep charge tagging)
Something like FASER is for the hadron collider, however, one has to dig tunnels for FASER-like things before.

### Organization points
Discussion will go on offline

• Workshop in November, we should have a presentation
  • what is available?
    • literature, code, tools
  • Benchmark list  
  • Linking people/interest
• Meet every 2 weeks, 1 hour
• Bring more people! just add in CC to emails.

 

15:00 → 15:20 Roundtable

We will collect some input:
- are you a theorist or an experimentalist?
- do you have prior experience on LLPs/FCC-ee?
- which kind of signatures are you interested in?

Speakers: Patrizia Azzi (INFN Padova (IT)), Rebeca Gonzalez Suarez (Uppsala University (SE))

15:20 → 15:40 Discussion on potential next steps

• theory/pheno: derive a short list (5-10?) of significant benchmarks that are also challenging in different ways the experimental reconstruction
• experimental:
  • sensitivity estimates using Delphes
  • reconstruction studies and development using FullSim
  • any other ideas (for instance ML approach to reco, use of timing etc... )

Speaker: Patrizia Azzi (INFN Padova (IT))

LLPIntro.pdf