Report on New Physics Subgroup Activities Nobuchika Okada (KEK) 5th general meeting of the ILC physics working group May 31, KEK Past activities Members: K. Fujii, H. Hano, H.Itoh, N. Okada, T. Yoshioka Result: One paper which is currently being reviewed in PRD ``Hidden particle production at the ILC,'' arXiv: [hep-ex] New Members (since April 3, 2008) K. Fujii, K. Ikematsu, H.Itoh, N. Okada, T. Suehara, R. Yonamine, T. Yoshioka

Current Activities ILC studies on tau & top in the final states What can we do with the ILC for the processes? ( We have meetings once two weeks ) Precision measurements of differential cross sections, polarizations of the final states, top quark decay width, …..anything else?  information on couplings for each helicity states Realistic Monte Carlo Simulations  precision goal Precision tests of the SM at high energy & Precision measurements of New Physics parameters ExpTh

Examples of new physics models relevant to our studies 1. Z’ models with flavor-dependent couplings A simple model: In general, Y_1,2 can be flavor dependent, keeping Y to be the same as in the SM  Z’ coupling can be flavor-dependent

Ex) Assume the same for the lepton sector

2. Bulk SM in Randall-Sundrum background geomentry Solution to gauge hierarchy problem  Higgs around TeV brane Fermion mass hierarchy  non-trivial bulk configurations C_i : order one parameter (bulk fermion mass)  changing a factor  creates hierarchy

Gauge hierarchy: Fermion mass hierarchy: Flavor-dependent couplings w/ KK gauge bosons

Light fermions  localized around Planck brane Heavy fermions  localized around TeV brane KK modes  localized around TeV brane  KK modes (KK gluon, KK Z- and W-bosons) strongly couple with top quark KK Z suppressed enhanced 10% shift for KK mass around a few TeV is possible

2. Little Higgs model (via mixing between heavy top and SM top) Little Higgs model: Higgs doublet is provided as NG modes Ex) Littlest Higgs model subgroup of global symmetry is gauged to be the SM gauge group Nonlinear sigma model under No quadratic divergence of Higgs mass^2 at 1-loop level with Little Higgs partner (heavey top) corrections via VEV

Vector-like SU(2) singlet top quark ``LH partner’’ is introduced Cancellation of quadratic divergence via T contributions Mass spectrum:

Anomalous top coupling with Z and W via t and T mixing Berger et al., hep-ph/ Anomalous coupling Anomalous top decay width

Quantities we can measure: By using (1) initial beam polarization (2) decomposition of differential cross section into that for each helicity final states (3) anomalous top quark decay width Precision level to achieve with the ILC  interpretations of New Physics model parameters

Signature of New Physics models Each new physics model predicts characteristic deviations of couplings from the SM ones Model example Flavor-dependent Z’ model Bulk SM in RS Little Higgs with T parity none none none none none none none none none Simulation studies  precision reach New physics parameters  model discrimination, search reach