Report on New Physics Subgroup Activities

Nobuchika Okada (KEK)

5th general meeting of the ILC physics working group

May 31, 2008 @ 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:0802.3943 [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

Exp Th

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/0512053

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 exampleFlavor-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