Phenomenology of supersymmetric TeV scale seesaw models

1
Phenomenology of supersymmetric TeV scale see-saw
models

• Gi-Chol Cho
• (Ochanomizu Univ.)
• in collaboration with
• Satoru Kaneko and Aya omote
• Seminar at MSU, Oct. 27, 2005

2
Tips

• Ochanomizu University
• womens university in Tokyo
• Location of Ochanomizu (????) area center of
  Tokyo
• Ocha (??) Tea
• mizu (?) water

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Phenomenology of supersymmetric TeV scale see-saw
models

• Gi-Chol Cho
• (Ochanomizu Univ.)
• in collaboration with
• Satoru Kaneko and Aya omote
• Seminar at MSU, Oct. 27, 2005

4
1. Introduction

• Origin of neutrino mass?
• effective operators for the lepton masses under
  the gauge group of SM
• then, the electron and neutrino masses are given
  as

L lepton doublet E right-handed electron H
Higgs
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1. Introduction

• a simple model which leads to a tiny neutrino
  mass
• mass matrix of neutrinos
• neutrino mass

N right-handed neutrino
see-saw mechanism Yanagida (79), Gell-Mann et
al (79)
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1. Introduction

• the see-saw mechanism
• neutrino Yukawa coupling O(1)
• right-handed neutrino mass 108 GeV
• hopeless to test the see-saw mechanism directly
• Alternative? (testable model)
• possible to lower the see-saw scale?

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TeV scale see-saw mechanism associated with the
supersymmetry breaking

• Arkani-Hamed, Hall, Murayama, Smith, Weiner,
  PRD64, 115011, 2001
• Borzumati, Nomura, PRD64, 053005, 2001
• March-Russell, West, PLB593, 181, 2004
• framework hidden sector SUSY breaking scenario
  (SUGRA)
• tool Giudice-Masiero mechanism for the
  -problem
• scale of the right-handed neutrino is given as a
  result of SUSY breaking
• the neutrino Yukawa is naturally suppressed

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-problem and Giudice-Masiero mechanism
Giudice, Masiero, 1988

• -problem in the minimal SUSY-SM
• superpotential
• scalar potential
• its scale must be O(mw) for EWSB
• however, an operator is invariant
  under the SM gauge group
• natural scale of the -term Planck scale?

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-problem and Giudice-Masiero mechanism

• introduce a global symmetry G
• Hu Hd massless via G
• superfield X singlet under GSM, but non-trivial
  under G
• v.e.v. of the F-comp. of X
• the following operator leads to small mu-term
  after SUSY breaking

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in this talk

• gauge invariant mass (i.e. right-handed neutrino)
  can be small owing to the Giudice-Masiero
  mechanism
• right-handed (s)neutrinos appear in the TeV (or
  EW) scale
• we discuss some phenomenological aspects of this
  framework

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Plan of this talk

• Introduction
• Model
• corrections to the lightest Higgs boson mass
• sneutrino production via charged Higgs decay
• Summary

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Model
Arkani-Hamed etal, (2001)

• Set-up
• a field X SM singlet, its v.e.v. breaks SUSY
• R-charges
• consider high. D operators in the leptonic sector

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Model

• If a field X develops both A- and F-component
  v.e.v.

Yukawa coupling 10-8
A-term 103 GeV
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Model

• right-handed neutrino mass
• then, neutrino mass matrix is given as

(v mSUSY )
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Model

• consequences of the model
• typical see-saw scale is O(TeV)
• neutrino Yukawa is naturally suppressed
• sneutrino A-term (SUSY breaking scalar trilinear
  coupling) is unsuppressed by the Yukawa coupling

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3. corrections to the lightest Higgs boson mass

• note that the lightest Higgs mass is determined
  by the Higgs quartic coupling
• since the scalar tri-linear coupling for
  , it may affect the lightest Higgs mass via
  1-loop correction

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destructively interferes with the corrections in
the MSSM (top quark, etc)
however, the correction is suppressed O(10-3) for

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4. sneutrino production via charged Higgs decay

• a typical process by a large (unsuppressed)
  A-term
• MSSM suppressed by lepton Yukawa couplings
• if slepton is ligter than chargino, it decays
  into charged lepton neutralino
• excess of charged lepton via charged Higgs decay
  can be expected as compared to MSSM/2HDM

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Interactions

• sources
• D-term int.
• scalar tri-linear int.
• in the MSSM, it is suppressed by charged lepton
  Yukawa coupling

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Interaction of TeV sneutrino

• sneutrino A-term is not suppressed by the Yukawa
  coupling
• decay rate could be increased for large A?

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decay modes of charged Higgs

• possible decay modes in SUSY-SM
• top bottom
• tau neutrino
• slepton sneutrino
• chargino neutralino
• hadronic decay squark quark
• squarks are assumed to be heavier than charged
  Higgs
• decay into gauge bosons
  is forbidden at the tree level because of the
  custodial symmetry

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Numerical study

• charged Higgs mass 250 or 350 GeV
• chargino neutralino mass
• chargino mass matrix
• inputs
• neutralino mass GUT relation
• slepton mass input ? sneutrino in MSSM is fixed
  through the SU(2) relation

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mH 250GeV
slepton mode in MSSM is kinematically forbidden
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mH 350GeV
slepton mode in MSSM is kinematically forbidden
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• therefore,
• is smaller than 56
• on the other hand,
• is 10
• therefore, excess of the number of charged lepton
  in the final state is expected

• decay to sleptonsneutrino overwhelms or is
  comparable with the tau mode because of large
  A-term for small tanß(3)
• when slepton is lighter than chargino, it
  dominantly decays into leptonneutralino
• chargino mode even if it has leptonic decay mode
  only, BR is 30 per each lepton flavor.

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discussion detectability

• measurement of the charged Higgs pair production
• a linear collider can do it at its threshold
• one of them can be confirmed through tb decay
• then we know that there is another charged Higgs
• typical size of production cross section of
  charged Higgs pair is O(fb)

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excess of charged leptons

• when the integrated luminocity is 100 fb-1,
  100-1000 charged Higgs pair is produced
• when tanß3, 1000 charged Higgs leads to
• 30 electrons (MSSM)
• 130 electrons (TeV seesaw)
• However we never see any excess if tanßgt10

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Recipe

• after discovery of charged Higgs, chargino,
  slepton
• in principle, MSSM prediction on of charged
  lepton can be made as a function of tanbeta and
  µ/M2
• determine tanbeta and µ/M2 from some hadronic
  processes
• if excess of leptons on (tanß,µ/M2) plan is
  found, it gives constraint on (A?, MR)

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Summary

• a possibility of TeV scale see-saw induced by
  SUSY breaking
• some phenomenological aspects have been discussed
• lightest Higgs boson mass is not affected (could
  not be a source to rise it)
• collider phenomenology charged Higgs decay
• signal could be an excess of charged leptons for
  small tanß
• how to test the model in the case of large tanß?
• flavor structure (neutrino mixing)?
• RGE with universal SUSY breaking terms?