Looking for the mirror world at ATLAS

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Looking for the mirror world at ATLAS

• Sandor Kazi

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The Standard Model
Group SU(3)C SU(2)L U(1)Y
Transformations Leptons lL
(1,2,-1) e-R (1,1,-2) Quarks
qL (3,2,1/3) uR (3,1,4/3) dR
(3,1,-2/3)
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The Exact Parity Model

• Add a set of mirror particles
• same charge
• same mass
• undergo same form and strength of interactions
• EXCEPT
• that the particles undergo right-handed weak
  interactions instead of left-handed ones.

The mirror matter transforms as a singlet in
ordinary matter space and vice versa.
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The Exact Parity Model
Group (SU(3)C SU(2)L U(1)Y) (SU(3)CM
SU(2)R U(1)YM)
Transformations Ordinary
matter Mirror matter Leptons
lL (1,2,-1)(1,1,0) lmR
(1,1,0)(1,2,-1) e-R
(1,1,-2)(1,1,0) e-mL (1,1,0)(1,1,-2)
Quarks qL (3,2,1/3)(1,1,0) qmR
(1,1,0)(3,2,1/3) uR
(3,1,4/3)(1,1,0) umL (1,1,0)(3,1,4/3)
dR (3,1,-2/3)(1,1,0)
dmL (1,1,0)(3,1,-2/3)
We have a discrete Z2 symmetry.
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Finding mirror particles
Conservation laws for ordinary matter and
mirror matter prevent particles with colour and
charge from interacting between the two forms.
But, interaction between colourless neutral
particles is allowed.
So lets look at a colourless neutral particle,
the Higgs boson.
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Finding mirror particles
Higgs Boson Ordinary matter Higgs FO
(1,2,1)(1,1,0) Mirror matter Higgs FM
(1,1,0)(1,2,1)
The 2 eigenstates of this symmetry are not the
physical Higgs bosons, but a superposition of the
two. F
(FO FM) Since this is an unbroken
symmetry, these states are also the mass
eigenstates.
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Ordinary Matter Higgs
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Searching for the Higgs
Higgs production mechanisms at ATLAS Dominant
channel is gluon fusion which includes LO gg
H Virtual gg
H gg Hg
qg Hq
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Higgs decay channels
LEP2 results indicate that the mH gt 115 GeV 95
C.L. From unitarity arguments, mH lt 1 TeV
115 GeV lt mH lt 150 GeV H gg Narrow peak
above irreducible background
130 GeV lt mH lt 200 GeV qq Hqq then H WW
emuu
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Including Mirror Matter
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EPM Higgs parameters
In the Exact Parity Model, the ordinary matter
propagator has two parameters, m and
m-. Convenient to express as Average mass (m
m-)/2 Separation in terms of width of SM
resonance (m - m-) nG
Since the width is not constant, but a function
of Higgs mass, the propagator needs to be
modified to allow for this. First approximation,
replace mG by sG/m.
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Finding the Mirror World

• Code the new physics cross-section into a Monte
  Carlo generator for instance, Pythia.
• Allow the Higgs to decay within the MC generator.
• Use ATLFAST to simulate the ATLAS detector.
• Write analysis routine to reconstruct the Higgs.
• Compare with SM.

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Finding the Mirror World
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Some further Investigations

• When is EPM distinguishable from the SM?
• What average Higgs mass
• What mass eigenstate separation
• Look at other decay channels that are in the SM.
• Also look at decays not present in SM but are in
  EPM.
• For example, if m gt 2m- then this is a possible
  decay path.