Hadronic production of light colortriplet Higgs

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Hadronic production of light color-triplet Higgs

• Gi-Chol Cho
• (Ochanomizu Univ.)
• Seminar at Tohoku University
• Jan/22, 2004
• in collaboration with K.Cheung (NCTS, Taiwan)
• Phys.Rev.D67075003,2003
• hep-ph/0306068 (to appear in PRD)

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1. Introduction

• three gauge couplings
• _at_ EW scale
• MSSM spectrum
• ? Grand Unification?

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in Grand Unified Theories

• quarks and leptons embedded into a certain
  large representation (e.g., 5, 10 in SU(5) )
• Higgs fields require colored partner fields to
  make a multiplet of SU(5)

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introducing colored Higgs bosons

• weak Higgs doublets Hu Hd in MSSM
• belong to 5 5 of SU(5)

responsible for electroweak symmetry breaking
O(100GeV)
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Constraints on mass of HC proton longevity

• D5 operator induces fast proton decay

• from super-K t? 6.7 x 1032yr
• bound on HC mass
• ? 7.2 x 1016GeV

Goto-Nihei, hep-ph/9909251
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a serious problem in GUTDoublet-Triplet
splitting
O(1016GeV)
O(100GeV)
explain this hierarchy naturally!
conventional approach too many works!
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Alternative approach to DT problem

• make the coupling of HC to the SM quarks/leptons
  small enough
• Three scenarios have been proposed
• Dvali(1996) forbid lowest Yukawa term by
  special discrete symmetry in SO(10)
• Haba, Maru(2002) small overlap of the wave
  functions in extra D direction
• Goldberger, Nomura, Smith(2002)

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Warped SUSY GUT
Goldberger-Nomura-Smith PRD67, 075021 (2003)

• MSSM fields locate on the Planck brane
• color triplets on the TeV brane
• wave function of color triplets is zero _at_ Planck
  brane
• Yukawa couplings to SM matters are suppressed
• mass of the color triplets suppressed by a warp
  factor
• gauge coupling unification is preserved at
  leading order level

• 5D SUSY SU(5) compactified on the orbifold S1/Z2
  AdS space with Planck and TeV branes
  (Randall-Sundrum scenario)

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Model independent consequences of these scenarios

• light (TeV scale) colored Higgs boson and
  higgsino
• they behave like stable particles in detector
• Can we find them at future hadron colliders?

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Outline

• Introduction
• Review of light colored Higgs
• Production at hadron colliders
• Detection
• Summary

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2. Review of light colored Higgs

• Higgs fields 5 5 in SU(5)

SU(3)C
U(1)Y
SU(2)L
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Interactions

• Interactions
• colored higgs/higgsinos cannot decay into SM
  particles directly ? stable particle in detector

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possible decay modes

• lighter one will be hadronized into color-neutral
  states
• electrically neutral
• electrically charged ? heavy muon
• novel signature
• charged track in central track chamber/silicon
  vertex detector
• penetration to the outer muon chamber

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3. Production at hadron colliders
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Pair production of colored Higgs boson
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parton-level cross sectionsHiggs boson
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parton-level cross sectionshiggsino
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total cross section
cut pseudo rapidity
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4. Detection
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two possible scenarios

• in addition to the direct production of the
  lighter state

in either case, a lighter particle will be
hadronized into electrically charged or neutral
state
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massive stable particle in detector

• penetrate the detector material
• energy loss in hadronic elastic scattering is
  negligible because of
• the small momentum transfer
• the huge mass difference between the TeV massive
  particle and the nucleon
• energy loss via hadronic collisions does not lead
  to detection of the massive partilce (no way to
  detect an electrically neutral state! )

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Search for a stable charged particle

• behaves like a heavy muon in detector
• ionizes detector materials with its energy loss
  -dE/dx
• dE/dx function of

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Search for a stable charged particle (2)

• upper limit on sensitivity of small
  dE/dx, from CDF (lt 0.85)
• (hep-ex/0211064)
• lower limit should be enough to penetrate to the
  outer muon chamber

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backgroud

• momentum cut is 250GeV for 1TeV particle
• high enough to be free from background of

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final states

• direct production of colored Higgs boson
• 1 or 2 Massive Charged Particles (MCP)
• decay of colored Higgs boson into colored
  higgsino gluino
• 1 MCP jets
• 2 MCPs jets

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number of observed events

• a factor ½ a half of colored Higgs/higgsinos
  will be hadronized into a charged particle
• an efficiency factor 0.8 for each detected track

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Number of events
more than 10 events for detection
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Number of events
more than 10 events for detection
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6. Summary

• TeV scale colored Higgs boson or higgsino an
  alternative signature of GUTs
• Production and detection of HC and were
  studied
• more than 10 events of pair production can be
  seen at LHC w/

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Life time of colored Higgs?

• May lead to cosmological problems
• relic density?
• exotic nuclei?