Ratio measurements for indirect searches for new physics

1. Ratio measurements for indirect searches for new physics • Precision measurements @LHC • Understand theory at level of EW and QCD radiative corrections  will be useful for disentangling these effects from new physics • Compare • Low p T and high p T phase space • Agreement at low p T and disagreement at high p T  strong evidence for new physics. • Ratio measurements are good for cancelling systematics • Luminosity • Jet energy scale and MET. discuss direct and indirect searches for new physics

2. First Example: Rjets • Rjets = s(Wln + 1-jet)/s(Zl+ l- + 1-jet) • Low p T region gives calibration • High p T region  model independent sensitivity to new physics but easy to think of models which would change Rjets, e.g. • SUSY c±would give more events with one lepton, increase Rjets • SUSY c0 could give more events with two leptons, decrease Rjets discuss direct and indirect searches for new physics

3. Rjets result from ATLAS • Rjets combined e and m channels • Agreement with SM • Decrease with pT because scale for two processes becomes more similar at high pT. discuss direct and indirect searches for new physics

4. Other Ratios • More inclusive Rjets, more variables. • Rbjets: same as Rjets with an identified b-jet. • Good for disentangling QCD effects because Wb and Zb very different. • Zinv = s(Znn+ jets)/s(Zl+l-+ jets) • Low pT  SM measurement • Deviation at high pT evidence for new physics. • Model independent dark matter search. • Other ratio we could study: s(g + jets)/s(Z + jets). • Sensitive to EW radiative corrections. discuss direct and indirect searches for new physics

5. Outlook • Ratios provide high precision measurements • Higher energy and luminosity running open up phase space for discovery. discuss direct and indirect searches for new physics