universidad nacional de colombia departamento de física
DESCRIPTION
Universidad Nacional de Colombia Departamento de Física. Grupo de Física Teórica de Altas Energías. Z’ Production in 331 models. Fredy A. Ochoa and Roberto Martínez. II LAWHEP São Miguel das Missões , Dec. 2007. Outlines. Motivations Z’ Basics: Theoretical and experimental facts - PowerPoint PPT PresentationTRANSCRIPT
Universidad Nacional de ColombiaUniversidad Nacional de Colombia
Departamento de FísicaDepartamento de Física
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São Miguel das MissõesSão Miguel das Missões, , Dec. 2007Dec. 2007
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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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Z’ Boson Basics:Z’ Boson Basics: Theoretical Theoretical FactsFacts
• 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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Z’ Boson Basics:Z’ Boson Basics: Experimental Experimental FactsFacts
• In hadron colliders, the sensitivity to Z’ production decaying intoIn hadron colliders, the sensitivity to Z’ production decaying into
quarks pairs is reduced compared to lepton pairs due to the QCDquarks pairs is reduced compared to lepton pairs due to the QCD backgroundbackground
• A Z’ particle is a resonance, which is more massive than the SM Z,A Z’ particle is a resonance, which is more massive than the SM Z,
observed in the Drell-Yan process pp(pp ) l l + X.observed in the Drell-Yan process pp(pp ) l l + X.
• A Z’ can be directly observed through its decay products. It is possibleA Z’ can be directly observed through its decay products. It is possible
in lepton collisions (ILC) or in hadron collisions (Tevatron, LHC).in lepton collisions (ILC) or in hadron collisions (Tevatron, LHC).
• Present limits from direct production at Tevatron and virtual effects atPresent limits from direct production at Tevatron and virtual effects at
LEP through mixing with the Z boson, imply that MLEP through mixing with the Z boson, imply that MZZ’ ~ TeV and S’ ~ TeV and S ~ 10. ~ 10.
• An observation of a Z’ would serve as a calibration point for futureAn observation of a Z’ would serve as a calibration point for future
detectorsdetectors
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¿What is ¿What is 331?331?
F. Pisano and V. Pleitez, Phys. Rev. D46, (1992) 410
P.H. Frampton, Phys. Rev. Lett. 69 (1992) 2889
qqLL : : (3, 3, Xq )(3, 3, Xq )
llLL : : (1, 3, Xl )(1, 3, Xl )
qqLL : : (3, 3, Xq )(3, 3, Xq )
llLL : : (1, 3, Xl )(1, 3, Xl )
SMSMSMSM 3-3-3-3-113-3-3-3-11
qqLL : : (3, 2, 1/6)(3, 2, 1/6)
llLL : : (1, 2, -1/2)(1, 2, -1/2) LL ==
qqRR : : (3, 1, 2/3)(3, 1, 2/3) llRR : : (1, 1, -1)(1, 1, -1)
R R ==
L =L =
qqRR : : (3, 1, X(3, 1, Xqq))
llRR : : (1, 1, Xl)(1, 1, Xl) R R ==
L =L =****
**
**
**
**
**
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¿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,
ZZ’ : Total Z’ width’ : Total Z’ width
s : C.M Energys : C.M Energy
ggv,a : v,a : Z’ couplingsZ’ couplings
y : rapidityy : rapidity
ppzz : long. momentum : long. momentum
E: total energyE: total energy
Scattering angleScattering angle
M = MM = Mffff : invariant mass : invariant mass
xxA,BA,B : momentum fractions : momentum fractions
K(M) : QED and QCD K(M) : QED and QCD correctionscorrections
Z’ at Z’ at TevatronTevatron
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Z’ at Z’ at TevatronTevatron
At NWA aproximation: (At NWA aproximation: (ZZ’/M’/MZZ’) << 1 ’) << 1 22
Total Z’ production Total Z’ production cross sectioncross section
Branching ratioBranching ratio
331 model with = -1/ 3 :
z’ / Mz’ ) ~ 4 x 10z’ / Mz’ ) ~ 4 x 1022 -- 4 4
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Z’ at Z’ at TevatronTevatron
Kinematics at CDF IIKinematics at CDF II
• pp collisions at C.M. energy s = 1.96 TeV,pp collisions at C.M. energy s = 1.96 TeV,
• Integrated Luminosity = 1.3 fbIntegrated Luminosity = 1.3 fb
• 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
• Events with invariant mass Mee > 200 GeV/cEvents with invariant mass Mee > 200 GeV/c
++ --
-1-1
22
• Central Calorimeter with pseudorapidity Central Calorimeter with pseudorapidity < 1.1 < 1.1
• Plug Calorimeter with pseudorapidity 1.2 < Plug Calorimeter with pseudorapidity 1.2 < < 3.6, < 3.6,
• Transverse energy ETransverse energy ETT > 25 GeV. > 25 GeV.
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Z’ at Z’ at TevatronTevatron
MMZZ’ > 920 GeV ’ > 920 GeV
T. Aaltonen et.al. (CDF Collaboration), T. Aaltonen et.al. (CDF Collaboration),
Phys. Rev. Lett. 99, (2007) 171802Phys. Rev. Lett. 99, (2007) 171802
331331(CalcHep Package)(CalcHep Package)Z’Z’SMSM
Z’Z’
Z’Z’
Z’Z’
Z’Z’331331
923923
822822
891891
822822
920920
Z’-modelsZ’-models 95% C.L. 95% C.L. BoundsBounds
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Z’ at Z’ at LHCLHC
Kinematics at ATLASKinematics at ATLAS
• pp collisions at C.M. energy s = 14 TeV,pp collisions at C.M. energy s = 14 TeV,
• Integrated Luminosity = 100 fbIntegrated Luminosity = 100 fb
• 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
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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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Scalar Structure (3 Scalar Structure (3 tripletes)tripletes)
8 Gauge Bosons
1 Gauge Boson
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Vector Structure (9 Vector Structure (9 campos)campos)
NeutralNeutralChargeChargedd
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