Top Physics at the ILC: A (selective) Review ILC Physics at Florence, GGI , Sept 12-14, 2007

Outline Review of some basic aspects of top physics Top Threshold Scan Top Pair + Higgs QCD Factorization for Top Mass Reconstruction New Physics EWSB Precision Test QCD ILC Physics at Florence, GGI , Sept 12-14, 2007

What we know … Tevatron (Run I+II) Tev, LHC, ILC Room for “fancy” New Physics ideas Tev, LHC, ILC Room for lots of “hard work” Top quark is SM-like ! ILC Physics at Florence, GGI , Sept 12-14, 2007

What ILC can/will do … Tevatron/LHC: ILC: first incisive tests of SM-top discovery potential for new physics: heavy resonances, FCNC decays,.. ILC: high precision measurements clean experimental environment precise theoretical calculations useful in any future scenario ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC EWSB New Physics EWSB Higgs mechanism Top Physics just a heavy quark ? active role in EWSB ? constraint on any model EWSB Higgs mechanism Top Physics Precision Physics QCD Laboratory Summation of QCD effects and polarization essential! 2nd part of talk ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC EWSB New Physics EWSB Higgs mechanism Top Physics just a heavy quark ? active role in EWSB ? constraint on any model EWSB Higgs mechanism Top Physics Precision Physics QCD Laboratory ILC Physics at Florence, GGI , Sept 12-14, 2007

Top FCNC’s ILC luminosity range Any signal clear indication for new physics! ILC luminosity range production more sensitive than decay (larger phase space) beam polarization improves sensitivity for production ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC Precision Physics: New Physics EWSB Top Physics top mass essential parameter for testing small error and precise mass def. needed EWSB any model at the quantum level Top Physics Precision Physics QCD Laboratory more examples see: Heinemeyer etal. hep-ph/0306181 ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC Top, the QCD laboratory: New Physics EWSB Top Physics top mass extremely large: short-distance top width: provides IR cutoff for low-energy EWSB processes have well convergent pert. exp. top quark dynamics Top Physics Precision Physics QCD Laboratory ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC Top, the QCD laboratory: New Physics EWSB Top Physics Chetyrkin, Kuhn, Steinhauser Teubner, AH, etal; Bernreuther etal, Denner, Pozorini etal Penin etal, etc. etc. Top Physics Jezabek, Kuhn, etal, Teubner, Stewart, Manohar, AH; Penin etal, Melnikov etal, Beneke, Signer etal, Sumino, Kiyo etal. Dittmaier etal, Dawson etal,; Denner/Delanger/You etal Farrell, AH Precision Physics QCD Laboratory ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Mass from Threshold Scan Miquel, Martinez; Boogert, Gounaris Threshold Scan “threshold masses” Theoretical Tool: NRQCD sums singularities ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Mass from Threshold Scan Miquel, Martinez; Boogert, Gounaris Threshold Scan “threshold masses” Theoretical Tool: NRQCD Fixed order pert. theory: LL, NLL NNLL (partly) Manohar, Stewart, Teubner; Stahlhofen, AH; Pineda, Signer RGE-improved pert. theory: LO, NLO, NNLO NNNLO (partly) Teubner AH; Melnikov Yelkovski; Yakovlev; Beneke, Signer Smirnov; Penin, Sumino, Kiyo; Schuller; ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Mass from Threshold Scan Miquel, Martinez; Boogert, Gounaris Threshold Scan “threshold masses” Main experimental problem: monitoring (Babbha) parametrization ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Mass from Threshold Scan Miquel, Martinez; Boogert, Gounaris Threshold Scan “threshold masses” “Official” ILC prospect: (Top/QCD working groups) ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Mass from Threshold Scan Miquel, Martinez; Boogert, Gounaris Threshold Scan “threshold masses” Outlook: (Top/QCD working groups) needed for measurements of completion of NNLL (RGE-improved) and NNNLO (fixed-order) total cross section Monte-Carlo for top threshold (total cross section + distribution) finite life-time corrections (non-factorizable, interference, distributions) application to squark pair production, etc. ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC Top, the QCD laboratory: New Physics EWSB Top Physics Chetyrkin, Kuhn, Steinhauser Teubner, AH, etal; Bernreuther etal, Denner, Pozorini etal Penin etal, etc. etc. Top Physics Jezabek, Kuhn, etal, Teubner, Stewart, Manohar, AH; Penin etal, Melnikov etal, Beneke, Signer etal, Sumino, Kiyo etal. Dittmaier etal, Dawson etal,; Denner/Delanger/You etal Farrell, AH Precision Physics QCD Laboratory ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Yukawa Coupling Top quarks are nonrelativistic very sensitive to CP property of Higgs Bhupal, Djuadi, Godbole, etal Top quarks are nonrelativistic Fixed order perturbation theory breaks down NRQCD treatment necessary very sensitive to CP properties of Higgs ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Yukawa Coupling factor 2 from summation of terms Farrell, AH NLL 1-loop tree hard Wilson coeff soft Green fct factor 2 from summation of terms factor 2 from polarization essential for realistic studies Juste ‘02, ‘06 tree-level, no polarization ILC Physics at Florence, GGI , Sept 12-14, 2007

Top at the ILC Top, the QCD laboratory: New Physics EWSB Top Physics Bernreuther, Brandenburg, etal, Parke, Shadmi etal., etc Bernreuther, Bonciani, Gehrmann, Heinesch, Leineweber, Mastrolia, Remiddi etal., Huber Top Physics Fadin, Khoze; Reisser, AH Beneke, Signer, Zanderighi, etal., Reisser AH Precision Physics QCD Laboratory Denner, Dittmaier, Roth, Wieders; Beenakker etal; Jadach etal. ILC Physics at Florence, GGI , Sept 12-14, 2007

Top Mass Measurements ILC Tev +LHC + ILC Threshold Scan Miquel, Martinez; Boogert, Gounaris ILC Threshold Scan “threshold masses” Tev +LHC + ILC Invariant Mass Reconstruction data available soon uncertainties (much) more involved many different methods available error around 1 GeV challenging What mass is measured? How to quantify a theory error? ILC Physics at Florence, GGI , Sept 12-14, 2007

ILC: Ideal Study Case Resonance region: ILC at large c.m. energy: No beam remnant : all soft radiation can be assigned to top or antitop Resonance region: ILC at large c.m. energy: Dijet limit: QCD factorization á la Korchemsky/Sterman related to thrust and heavy jet mass event shapes set up similar to Chekanov/Morgunov analyis except for use of k_T ILC Physics at Florence, GGI , Sept 12-14, 2007

Factorization Theorem Fleming, Mantry, Stewart, AH hep-ph/0703207 SOFT QCD JET JET SCET HQET SOFT LO factorization theorem JET JET SOFT ILC Physics at Florence, GGI , Sept 12-14, 2007

Factorization Theorem Jet functions: perturbative, any mass scheme depends on → “jet” mass Breit-Wigner at tree level Soft function: non-perturbative renormalized due to UV divergences also governs massless dijet thrust and jet mass event distributions Short distance top mass can (in principle) be determined to better than . Korshemsky, Sterman, etal. Bauer, Manohar, Wise, Lee ILC Physics at Florence, GGI , Sept 12-14, 2007

Closing Remarks .. ILC is a precision machine … .. I only touched a few interesting issues … .. plenty of interesting conceptual things to work on … .. QCD aspects of top are no free lunches, needs hard work … .. even in the beyond-SM era… ILC Physics at Florence, GGI , Sept 12-14, 2007

Backup Slides ILC Physics at Florence, GGI , Sept 12-14, 2007

LO Numerical Analysis Single differential distribution: Non-perturbative effects shift the peak to higher energies and broaden the distribution. ILC Physics at Florence, GGI , Sept 12-14, 2007

LO Numerical Analysis Different invariant mass prescriptions/soft functions: Fairly precise determination of jet mass from determination of Q-dependence of the peak position and extrapolation Q to zero ILC Physics at Florence, GGI , Sept 12-14, 2007

Short-distance Top Jet Mass One-loop: shift in the pole scheme 300 MeV shift in the pole scheme contains renormalon jet mass scheme: defined such that peak located at the mass to all orders What mass is measured? Answer: the one that gives the best convergence in the theoretical expansion. Top Jet mass is the scheme where we expect that a LO analysis contains the least theoretical uncertainties. ILC Physics at Florence, GGI , Sept 12-14, 2007

ILC Top Mass Reconstruction Chekanov, Morgunov hep-ex/0301014 All-hadronic channel Event Selection every particle is assigned to top or antitop (fully inclusive !!) ILC special k_T (Durham) jet algorithm all particles are assigned to exactly 6 jets reduces events for massless quark pair production selects hadronic events Top Reconstruction 6 jets with momenta group in pairs of 3: b-tagging massless jet pair mass: both invariant masses close to selects back-to-back events reduces combinatorics Analysis: ILC Physics at Florence, GGI , Sept 12-14, 2007

Event Shapes e.g. Thrust distribution on the peak region: Chekanov; Morgunov hep-ex/0301014 ILC Physics at Florence, GGI , Sept 12-14, 2007

Theory Issues for definition of jet observables initial state radiation final state radiation underlying events color reconnection & soft gluon interactions beam remnant parton distributions summing large logs relation to Lagrangian short distance mass Can be addressed in the framework of the ILC. Requires extensions of ILC concepts and other known concepts Hadron event shapes ILC Physics at Florence, GGI , Sept 12-14, 2007

ATLAS Reconstruction Methods Lepton + Jets Plain Method: W reconstruction + b tagging Inv. mass from 100.000 events after cuts Major error sources: b jet energy scale: FSR jets: Kinematic Fit: reconstruct entire event impose constraints ( e.g. ) vary unknows freely b jet energy scale: FSR jets: Continuous Jet Definition: plain method for varying cone size: take weighted average FSR error reduced Large Events: select events with top pair back-to-back decay products in different hemispheres large cone size around top/antitop jet axes: and from in-cone momenta strong sensitivity to soft jets + Underlying Events Mass scale calibrations (W mass) UE: calibration ILC Physics at Florence, GGI , Sept 12-14, 2007