ECFA HTE mini-workshop on e+e- physics at 125 and 160 GeV
Hee coupling (David D'Enterria)
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- what about interference between Z & H?
o Very small: spin-0 component of Z has same m_e dependence as signal, interference is suppressed by 1/(s-mZ^2)
- have you considered e+e- -> Z/gamma* --> qqbar loop --> gluon gluon (cannot happen C-conservation, but can have radiation)
o more problematic is e+e- --> qqbar where the quarks radiate a hard gluon (or are mistagged)
- H->gg most significant, requires 70% tagging efficiency with 99% rejection of quarks
- H->WW*->lvjj next most significant
- if we can have ~MeV spread we can get discovery with ~20/ab luminosity (multiple interactions)
Higgs mass (Jan Eysermans)
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- measure the dimuon or dielectron recoil mass (Z->mu-mu or Z->ee)
o 3.8 MeV statistical uncertainty, dominant systematic is beam enery spread
o what about muon hit/curvature resolution uncertainty? material uncertainty?
o muon momentum scale constrained to 10^-6 using Zs?
- can obtain ~5 MeV uncertainty by measuring rising ZH cross section -- most sensitive energy is at 217 GeV
o suppress systematics by taking ratio of cross sections -- any uncertainty from beam energy spread? small
o can you investigate the gain in precision from using both methods when you have high statistics>
Energy recovery in e+e- linacs at 125 GeV (Vladimir Litvinenko)
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- energy recovery linacs have potential to produce 90/ab of luminosity per year with energy spread of 1.4 MeV
o very interesting for electron Yukawa! but will need to investigate wakefields etc to ensure validity
- is large vertical disruption a concern? should be okay