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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