Universidad Nacional de Universidad Nacional de Colombia Colombia Departamento de Física Departamento de Física II LAWHEP II LAWHEP São Miguel das Missões São Miguel das Missões , , Dec. Dec. 2007 2007 Grupo de Física Teórica de Altas Grupo de Física Teórica de Altas Energías Energías Z’ Production in 331 models Z’ Production in 331 models Fredy A. Ochoa and Roberto Martínez
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Universidad Nacional de Colombia Departamento de Física II LAWHEP São Miguel das Missões, Dec. 2007 II LAWHEP São Miguel das Missões, Dec. 2007 Grupo de.
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Universidad Nacional de ColombiaUniversidad Nacional de Colombia
Departamento de FísicaDepartamento de Física
II LAWHEPII LAWHEP
São Miguel das MissõesSão Miguel das Missões, , Dec. 2007Dec. 2007
II LAWHEPII LAWHEP
São Miguel das MissõesSão Miguel das Missões, , Dec. 2007Dec. 2007
Grupo de Física Teórica de Altas EnergíasGrupo de Física Teórica de Altas Energías
Z’ Production in 331 modelsZ’ Production in 331 models
Fredy A. Ochoa and Roberto Martínez
II LAWHEPII LAWHEP
São Miguel das MissõesSão Miguel das Missões, , Dec. 2007Dec. 2007
• Motivations Motivations
• Z’ Basics: Theoretical and experimental factsZ’ Basics: Theoretical and experimental facts
• The 331 ModelThe 331 Model
• Z’ Production at TevatronZ’ Production at Tevatron
• Z’ Production at LHCZ’ Production at LHC
• Conclusions and ProspectsConclusions and Prospects
OutlineOutliness
• The mechanism for breaking the electroweak symmetries andThe mechanism for breaking the electroweak symmetries and generating massgenerating mass
• The unification of forces, including gravity.The unification of forces, including gravity.
• The conection to cosmology (Baryon asymmetry, Cold Dark The conection to cosmology (Baryon asymmetry, Cold Dark Matter. ) Matter. )
• The mass hierarchy problemThe mass hierarchy problem
• The existence of 3 familiesThe existence of 3 families
• The electric charge quantizationThe electric charge quantization
• The neutrino masses and mixingThe neutrino masses and mixing
¿Why beyond ¿Why beyond SM?SM?
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II LAWHEPII LAWHEP
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• An observation of the Z’ would provide information on the GUT groupAn observation of the Z’ would provide information on the GUT group and on its symmetry breakingand on its symmetry breaking..
• A Z’ particle is a neutral, spin-1, colorless and self-adjoint gauge bosonA Z’ particle is a neutral, spin-1, colorless and self-adjoint gauge boson arising from some extensions of the SM, which is more massive than thearising from some extensions of the SM, which is more massive than the
SM Z boson.SM Z boson.
• Z’-models: +U(1) from E6, Left-Right, Little Higgs, Sequential SM, 331Z’-models: +U(1) from E6, Left-Right, Little Higgs, Sequential SM, 331
• Z and Z’ bosons are not true mass eigenstates. The physical bosons areZ and Z’ bosons are not true mass eigenstates. The physical bosons are
mixing states Zmixing states Z11 and Z and Z22 with a mixing angle with a mixing angle , which cause deviations from, which cause deviations from the SM (Z-pole parameters, shifts in the W couplings, shifts in the Weakthe SM (Z-pole parameters, shifts in the W couplings, shifts in the Weak Charge, F-B Asymmetries, etc.)Charge, F-B Asymmetries, etc.)
• The MThe MZZ’ is not constrained by the theory. It can be anywhere between’ is not constrained by the theory. It can be anywhere between
Eweak < MEweak < MZZ’ < E’ < EGUTGUT..
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São Miguel das MissõesSão Miguel das Missões, , Dec. 2007Dec. 2007
São Miguel das MissõesSão Miguel das Missões, , Dec. 2007Dec. 2007
¿Why 331?¿Why 331?
• From cancelation of Chiral Anomalies and asymptotic freedom, From cancelation of Chiral Anomalies and asymptotic freedom, thethe number of families should be 3number of families should be 3
• The third family is different from the two first, which could The third family is different from the two first, which could explainexplain why the t and b quarks are so heavy (hierarchy problem)why the t and b quarks are so heavy (hierarchy problem)
• Predict the quantization of electric charge and the vector nature Predict the quantization of electric charge and the vector nature of EM.of EM.
• Contains a natural Peccei-Quinn symmetry Contains a natural Peccei-Quinn symmetry
• New types of matter relevant at LHCNew types of matter relevant at LHC
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Fermion Structure (3 flias.)
If = -1/ 3:QE = 0 EL = (R) c
NeutralNeutral
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Neutral Neutral CurrentsCurrents
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Cross section for pp Z’ f fCross section for pp Z’ f fffq/A q/A : PDFs,: PDFs,
• Azimuthally and F-B symmetric,Azimuthally and F-B symmetric,
• Search for Z’ in the channel qq Z’ e e Search for Z’ in the channel qq Z’ e e ++ --
-1-1
• Pseudorapidity Pseudorapidity < 2.5 < 2.5
•Transverse energy ETransverse energy ETT > 20 GeV. > 20 GeV.
Z’ at Z’ at LHCLHC
for Mz’ = 1500 GeVfor Mz’ = 1500 GeV
N = N = LL
Z’ at Z’ at LHCLHC
LHC Projections for 1 TeV < MZ’ < 5 TeVLHC Projections for 1 TeV < MZ’ < 5 TeV
N = N = LL
Z’331
Z’LR
Z’
Z’
SM bkg
Z’
ConclusioConclusionsns
• For 331 model with For 331 model with = -1/ 3, we get the limit Mz’= -1/ 3, we get the limit Mz’331331 > 920 > 920 GeV atGeV at 95% C.L in Tevatron95% C.L in Tevatron
• For Mz’ = 1500 GeV, we get about 800 events for each 20 GeV For Mz’ = 1500 GeV, we get about 800 events for each 20 GeV
ofof energy with L = 100 fb at LHCenergy with L = 100 fb at LHC
• At Mz’ = 1 TeV we found ~ 10.000 events with low expected SM At Mz’ = 1 TeV we found ~ 10.000 events with low expected SM
bcgbcg
• The model pull the LHC dicovery potential up to 5 TeV, with 1 The model pull the LHC dicovery potential up to 5 TeV, with 1
event event
-1-1
ProspectsProspects
• Calculations for other 331 models and other Mz’ limitsCalculations for other 331 models and other Mz’ limits
• Effects of exotic decay modes as fermions, charged heavyEffects of exotic decay modes as fermions, charged heavy bosons, higss, etc (smaller branching ratios)bosons, higss, etc (smaller branching ratios)
• Effects on the lepton F-B Asymmetries Effects on the lepton F-B Asymmetries
• Extension to ILCExtension to ILC
Back Back silidessilides
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