Bi-weekly meeting of Snowmass energy frontier topical group EF03 (top and heavy flavor production). We will give a chance for everyone to prepare 5-minute presentations to show their plans. We will also have plenty of time for discussion.
The meeting will be on zoom at https://msu.zoom.us/j/93067817156?pwd=YlY2S04xMzd5ODBvUkVoWmtJc1MvZz09. The meeting password on zoom is 202021.
Intro:
- Comment from Marcel on many years without top quarks being produced: This focus on lower-energy lepton collider hurts the important top-quark program, need to emphasize that we need two colliders, one (for example circular) machine for Z and Higgs, and one that can reach top threshold for broader explorations - ILC or CLIC.
Clement:
- No specific studies done for HE-LHC, here focus on HL-LHC. HE-LHC is in any case not a priority.
- 4-top: simpler analysis than evidence announced by ATLAS - which had evidence (>3 sigma), though expected significance not as large as 3 sigma.
- Scaling assumption of systematic uncertainties - will likely differ case by case. For example (ttgamma, page 11), is this realistic? ttbar would be dominated by lumi uncertainty, which wouldn’t scale.
- upgrade studies in ATLAS and CMS would benefit from studies or more careful evaluations done in the context of Snowmass.
- More realistic study of what could be achieved at HL-LHC could be a LOI for Snowmass, just scale existing studies and work out dependence on systematic uncertainties. - Marcel interested in this, we could also put out a call for volunteers on this - low threshold to start.
- studies shown here could also be extended, and anything that didn’t finish on time, can be done for Snowmass.
- Other analyses (that didn’t finish but are interested in finishing) could also contribute, some of which may be done from inside ATLAS, eg s-channel single top. Others might be done by anyone.
- mass extrapolation - for several of these, we now have results (Run 1, and alternative measurements in Run 2.
- lot of space for Snowmass studies on top physics for HL-LHC and FCC-hh
Discussion:
- Clement has slides, gives the disclaimer that he’s been an advocate of FCC for many years.
- Running plan for FCC-ee is not clear, nominally top physics (threshold scan) after 10 years, but there are competing programs that are interesting, and high energy requires a lot of RF cavities and electrical power, i.e.money.
- ESG emphasizes need for Higgs factory, but doesn’t actually say that it has to be built in Europe. Of course it also discusses Higgs factory followed by hadron machine (FCC) in the next paragraph.
- Intervening years before Higgs factory might bring theoretical improvements that would help top results from HL-LHC. And Higgs factory itself would improve for example hadronization uncertainties, which would also improve HL-LHC top results.
- Would be great if outcome of Snowmass is that having an e+e- top-producing machine is important, not just for top physics, but also if this can help improve parameters that will be needed elsewhere (for FCC-hh for example).
- there was a study by Blondel and Janot on complimentarity of ILC and circular Higgs factory (https://inspirehep.net/literature/1773245)
- Ratios of cross-sections will help in reducing uncertainties at lepton colliders, but this also requires additional assumptions.