1. Charged Higgs boson decay in supersymmetric TeV scale seesaw model
Gi-Chol Cho
(Ochanomizu Univ.)
in collaboration with
S. Kaneko (Valencia, Spain) and A. Omote (Ochanomizu)
Joint Meeting of Pacific Region
Particle Physics Communities conference
Oct/30-Nov/03, 2006
Oct/31/2006
Gi-Chol Cho

2. 1. Introduction origin of small neutrino mass?
a smart explanation: seesaw mechanism (Yanagida, Gell-Man etal., )
too heavy “new particle”
hopeless to test the seesaw mechanism directly
Alternative? (testable model)
possible to lower the seesaw scale?
Oct/31/2006
Gi-Chol Cho

3. TeV scale see-saw mechanism associated with the supersymmetry breaking
Arkani-Hamed, Hall, Murayama, Smith, Weiner, PRD64, , 2001
Borzumati, Nomura, PRD64, , 2001
March-Russell, West, PLB593, 181, 2004
framework: hidden sector SUSY breaking scenario (SUGRA)
purpose: lower the right-handed neutrino mass (gauge invariant mass) to be O (1TeV)
tool: Giudice-Masiero mechanism for the “ -problem”
SUSY and gauge invariant mass term in the superpotential
need to be the electroweak scale from the minimization condition of the Higgs potential
Oct/31/2006
Gi-Chol Cho

4. -problem and Giudice-Masiero mechanism
Hu + Hd … massless via a certain global symmetry G
a chiral superfield X: singlet under GSM, but non-trivial under G
v.e.v. of the F-comp. of X :
“small” mu-term arises from the following operator after SUSY breaking
gauge invariant mass (naturally ~Planck mass) could be lowered to the EW scale
Oct/31/2006
Gi-Chol Cho

5. Plan of this talk
study phenomenological consequences of the model in which the right-
handed neutrino mass is lowered by the Giudice-Masiero mechanism
Introduction
Model
corrections to the lightest Higgs boson mass
sneutrino production via charged Higgs decay
Summary
Oct/31/2006
Gi-Chol Cho

6. Model Set-up (Arkani-Hamed etal, 2001)
Arkani-Hamed, Hall, Murayama, Smith, Weiner, PRD64, , 2001
Borzumati, Nomura, PRD64, , 2001
March-Russell, West, PLB593, 181, 2004
Set-up (Arkani-Hamed etal, 2001)
a field X: SM singlet, its v.e.v. breaks SUSY
R-charge
consider high. D operators in the leptonic sector
Oct/31/2006
Gi-Chol Cho

7. Model right-handed neutrino mass:
then, neutrino mass matrix is given as
(v ~ mSUSY )
Oct/31/2006
Gi-Chol Cho

8. Model If a field X develops both A- and F-components v.e.v.
Yukawa coupling ~ 10^-8
A-term ~10^3 GeV
Oct/31/2006
Gi-Chol Cho

9. Model consequences of the model typical see-saw scale is O(TeV)
neutrino Yukawa is naturally suppressed
sneutrino A-term is not suppressed by the Yukawa coupling (in the MSSM, it will appear as a product w/ Yukawa)
Oct/31/2006
Gi-Chol Cho

10. 3. corrections to the lightest Higgs boson mass
large SUSY breaking mass limit: a lightest Higgs mass is determined by the quartic coupling in the (SM) Higgs potential
the scalar tri-linear coupling of 　　　　　　　　　 may affect the lightest Higgs mass through 1-loop correction
Oct/31/2006
Gi-Chol Cho

11. negative contribution from the sneutrino loop diagram
destructively interferes with the corrections in the MSSM (top quark, etc)
Oct/31/2006
Gi-Chol Cho

12. Rh decreases for large Aν
sneutrino loop negatively interferes w/ the top-stop contributions
however, the correction is smaller than 2% for
Oct/31/2006
Gi-Chol Cho

13. 4. Sneutrino production in charged Higgs decay
a typical process by a large (unsuppressed) A-term:
MSSM: suppressed by lepton Yukawa couplings for first two generation
Oct/31/2006
Gi-Chol Cho

14. decay modes of charged Higgs
(top + bottom), (tau + neutrino)  overwhelmingly dominant in the MSSM
selectron + sneutrino: enhanced due to the large A-term
selectron may decay into electron + neutralino  signal?
chargino + neutralino
chargino may decay into electron + sneutrino
could be background of the slepton+sneutrino mode
detectability of the signal may depend on properties of chargino/neutralino
Oct/31/2006
Gi-Chol Cho

15. example 1: higgsino like case
lighter chargino/neutralino are almost higgsino
mode is highly suppressed because of no Higgs-higgsino-higgsino vtx.
Oct/31/2006
Gi-Chol Cho

16. example 2: mixed case
the chargino+neutraino mode is larger than the sneutrino+slepton mode  a serious background
Oct/31/2006
Gi-Chol Cho

17. discussion
Oct/31/2006
Gi-Chol Cho

18. discussion @ILC w/ 100fb^-1 luminosity
production cross section of ch.Higgs pair~10fb
# of charged Higgs pair: /yr
(ex) tanβ=3 and
O(1) electrons: MSSM
~160 electrons (SUSY seesaw)
such a signal can be expected only for tanβ>10 and　　　　　　　　
Oct/31/2006
Gi-Chol Cho

19. Summary phenomenology of the TeV scale SUSY see-saw model
large (unsuppressed) scalar trilinear coupling
sneutrino contribution to the lightest Higgs mass
destructively interferes w/ the top-stop loop, but small
sneutrino production from the charged Higgs decay is enhanced in some parameter space
signal:
excess of electrons from charged Higgs decay in some parameter space (tanβis small and a chargino is almost higgsino)
Oct/31/2006
Gi-Chol Cho