Snowmass energy frontier top group meeting

Europe/Zurich
Vidyo and phone meeting

Vidyo and phone meeting

Description
This is the regularly scheduled meeting of the top quark group for Snowmass 2013. More information can be found on the Snowmass top group web page at http://www.snowmass2013.org/tiki-index.php?page=Fully+Understanding+the+Top+Quark.

The meeting is at 9am Central time, 10am Eastern time. Note that Daylight Savings Time starts on March 10 in the US and on March 31 in Europe, thus the starting time for this meeting is 15:00 at CERN, and hour earlier than usual.
26 participants on vidyo, 4 people in the room at FNAL

Tao Han:
- Ayres: ILC (NLC) numbers old, now estimate less than 10MeV for W mass, less than 100MeV for top mass. But muon collider has other advantages. Tao: note estimated sensitivity on p 34 is quite a bit better than that.
- Why not top-Higgs? Why not more precisely in threshold scan? Assume can do ttH at LHC, then will reach sensitivity better than muon collider. One-loop correction from Higgs exchange in muon collider is small and not dominant at muon collider, thus will not provide sensitivity. But this will depend on well LHC will do eventually.
- top reconstruction at e vs mu collider? More hostile environment at muon collider with much more beam background, neutrinos, scattering decay products. Likely need to be away from beam direction by a 10 degree cone or so. But top physics is central, thus expect top physics not to be impacted much. Also, detectors are not as easy as in e+e-. But still much easier than hadronic collider detectors.
- If cone that has to be excluded goes out to 20 degrees then will likely lose real physics, while 10 degrees is probably manageable for top physics. Tao: there are efforts by muon collider detector people to bring this down to 6 degrees, so 20 degrees unlikely.
- Tao: if need to move forward, happy to direct people and help out.
- Ayres: why not try ttH production at muon collider? XS not big, but should be small bkg. Tao: yes, likely a better process, worthwhile studying.

Andreas Jung:
- yes, will document what else is needed and desirable
- Sergei: will update all samples once the "snowmass LHC detector" has been decided, which will be average of CMS and ATLAS.
- Sergei: previous Delphes version had b-tagging bug, this was fixed by hand, but now Delphes 3 should have this fixed.
- If someone needs to process their own samples for example with different couplings, just provide hep-mc record. Once that is available, Sergei can process the rest and provide samples for analysis.
- Gregory: Have you considered madgraph? Sergei: Yes, would like help from someone in extracting hep-mc record from madgraph.
- Sergei can also provide example analysis code.


Status report from contacts:
1. Mass:
- have invited Frank Simon and Sasha Penin.
- Also hoping to get one of the authors of a new paper that will come out in a week or so with an alternative LHC mass measurement method.

2. Couplings:
- Already have good list for theory discussion (three speakers), for experiment have been working on updating list on twiki, but don't have agenda yet. Looking for speaker who could present top coupling measurement at ILC, which is on DVD for ILC detectors. ILC people are looking for speaker.

3. Kinematics: (Markus Schulze, Jessie Shelton)
- want to look at ttZ, want to repeat Baur analysis at NLO, including spin correlation and corrections.
- Also looking at ttbar mass and ttbar pair pT studies to understand tail of those distributions better.
- also thinking about f/b at LHCb (Andreas), trying to find someone from LHCb to talk about this.
- don't yet have organized slate of people, but have been talking about projects just by email

4. Rare decays: (Nathaniel Craig)
- Sharing with couplings session, need to coordinate, will ask theory speakers to also address rare decays in their talks
- Still working on details of experimental section

5. New particles: (Andrew Ivanov)
- contacted people but don't have many responses yet.
- Might try to get in touch with groups at CMS and ATLAS who are working on the relevant analyses
- Reinhard: Will have to coordinate with NP group as well, they contacted us.

6. Top and detectors: (Sergei, Roman)
- contacts are talking to each other, will discuss Fri
- Right now not much activity,  so far no possible speakers, maybe conveners will give overview presentations


Other:
- Next meeting will be BNL meeting. Everybody is strongly encouraged to attend. Likely will also have vidyo available for those who really cannot make it.
There are minutes attached to this event. Show them.