Preon physics at LHC

Preon physics at LHC
Philippe Mermod
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• Dark matter
• Unification
• Hierarchy
SM problems and weaknesses
• Neutrino masses
• Matter/Antimatter Ass.
• Gravitation
• Elementary particles :
! Too many
! Unstable
! Unpredictable masses
! Oscillations/mixing
! Charge quantization
! Lepton and baryon number conservation
" W and Z are massive
! Higgs still escapes detection
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Possible remedy : composite leptons,
• Dark matter
quarks and vector bosons
# preon stars and new neutrinos
• Unification
# no fundamental weak force
• Hierarchy
# no higgs mechanism
• Neutrino masses
# neutrinos are composite
• Matter/Antimatter Ass.
# as many preons as antipreons
• Gravitation
• Elementary particles :
! Too many
# 3 preons
! Unstable
# rearrangement among preons
! Unpredictable masses
# preon dynamics ?
! Oscillations/mixing
# same net preon flavour
! Charge quantization
# only 1/3e and 2/3e
! Lepton and baryon number conservation
# explained but can be broken
$ W and Z are massive
# preon-antipreon states
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Preon-trinity model
J.-J. Dugnes, S. Fredriksson and J. Hansson,
Europhys. Lett. 60, 188 (2002)
• Three preons in total
• They can form tight dipreon pairs
• Lepton = preon + dipreon
• Quark = preon + anti-dipreon
• Vector boson = preon + anti-preon
• The model is qualitative, it still lacks a dynamics
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Model predictions (1)
• One new charged heavy lepton
• Two new neutrinos
• Three new heavy quarks (one with charge 4/3)
• Two new heavy vector bosons
• Good sign : the top quark is among the super-heavies
(with isolated !)
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• No Higgs boson
Model predictions (2)
• The third oscillating neutrino is not the ! " :
instead it is a new one, which does not couple to
the Z
• The top quark decay involves a new heavy
• ...
vector boson
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The neutrino front
• Neutrino masses and oscillations easily
explained in the model
• On the CNGS beam, experiments like OPERA
plan to measure directly " leptons from ! "
interactions " not expected to happen in the
preon model !
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Tevatron and LHC front
• New exotic heavy particles
• New exotic decay channels
• Richer top sector
• Lepton and quark excited states
• New interpretation in case of non-discovery of
Higgs
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• # + lepton :
New heavy lepton
– Very weak production at hadron colliders
– Decay involves very hard single #$%&'( with very large MET
and no jets
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• t quark :
Heavy quark decays
– Decay involves a W' (which in turn might decay into W +
neutrinos)
• e, $ and " are not on the same footing
• can try to reconstruct the W' invariant mass if lighter than
the top mass
– New decay mode involving a Z*
• specific signature : 1 hard jet (not a b-jet) + large MET
• h and g quarks :
– Same decays as t, but with no b-jets
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Summary
• The preon trinity model can qualitatively
explain all features of the SM
• It solves many problems of the SM
• It predicts new physics which are expected to
show up at LHC
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Outlook
• The model can easily be killed (Higgs
discovery, OPERA experiment, refined top
decays)
• We can produce a paper on potential
signatures at LHC
• If deviations from SM are seen, they might be
interpreted in terms of compositeness
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