Top/QCD program

(b)

Higher Order EW + QCD

Fixed order vs resummed Normalization (and peak position) stabilised by higher orders; –summation of leading logs important –N 3 LO improves NNLO considerably Pineda

Instability Effects

Experimental threshold complicated by beam effects –Luminosity spectrum –Absolute beam energy Machine parameters (interaction point beam sizes) change beamstrahlung component of luminosity spectrum Increase beamstrahlung reduces effective luminosity at threshold –Small modification to shape Threshold top quark production Boogert, Gournaris

ILC accelerator parameters Parameter group question Is there any impact of decreasing (increasing) beamstrahlung by a factor of two relative to the standard parameters ? Simulated 5 possible scenarios Low-Q, Nominal, Large-Y, Low-P, High-L Simulated using Guinea-Pig –Fitted using CIRCE-like parameterization Total luminosity spectrum also includes –Intrinsic energy spread –Initial state radiation Bhabha acolinearity –Theoretical developments New 2 loop calculations Monte Carlo generators –Beamstrahlung extraction Statistical error small Systematic errors being evaluated Boogert, Gournaris

Projected total top mass error Statistical error –Obtained directly from threshold fit  m t (stat-fit) = 100 to 15 MeV –Depends on parameter set Theory error (estimate) –From theoretical uncertainty in threshold cross section  m t (theory) = 35 MeV Absolute beam energy scale –Assumed precision of beam energy diagnostics 1 part in 10 4  m t (e-beam) = 35 MeV Luminosity spectrum –Beamstrahlung component can be well measured –K. Mönig & S. Boogert –Systematic error studies ongoing  m t (spectrum) = 2 MeV and 70 MeV Boogert, Gournaris

At the ILC with, several hundred events are expected. Statistical error is less than 10 %. Therefore the effect of dim.6 couplings can be observed. –We discuss the W-fusion with the non-SM Y t which are characterized by dim.6 operators. –They are constrained by experimental data and unitarity. Our calculations have been checked by ET. The W-fusion has been analyzed by EWA and CalcHEP. Dim.6 couplings can enhance. Dimension 6 top-Higgs coupling Conclusion Koji Tsumura