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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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Presentation on theme: "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."— Presentation transcript:

1 Universidad Nacional de Colombia Departamento de Física II LAWHEP São Miguel das Missões, Dec II LAWHEP São Miguel das Missões, Dec Grupo de Física Teórica de Altas Energías Z Production in 331 models Fredy A. Ochoa and Roberto Martínez

2 II LAWHEP São Miguel das Missões, Dec Motivations Motivations Z Basics: Theoretical and experimental facts Z Basics: Theoretical and experimental facts The 331 Model The 331 Model Z Production at Tevatron Z Production at Tevatron Z Production at LHC Z Production at LHC Conclusions and Prospects Conclusions and Prospects Outlines

3 The mechanism for breaking the electroweak symmetries and The mechanism for breaking the electroweak symmetries and generating mass generating mass The unification of forces, including gravity. The unification of forces, including gravity. The conection to cosmology (Baryon asymmetry, Cold Dark Matter. ) The conection to cosmology (Baryon asymmetry, Cold Dark Matter. ) The mass hierarchy problem The mass hierarchy problem The existence of 3 families The existence of 3 families The electric charge quantization The electric charge quantization The neutrino masses and mixing The neutrino masses and mixing ¿Why beyond SM? II LAWHEP São Miguel das Missões, Dec. 2007

4 II LAWHEP São Miguel das Missões, Dec Z Boson Basics: Theoretical Facts An observation of the Z would provide information on the GUT group An observation of the Z would provide information on the GUT group and on its symmetry breaking. and on its symmetry breaking. A Z particle is a neutral, spin-1, colorless and self-adjoint gauge boson A 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 the arising 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, 331 Z-models: +U(1) from E6, Left-Right, Little Higgs, Sequential SM, 331 Z and Z bosons are not true mass eigenstates. The physical bosons are Z and Z bosons are not true mass eigenstates. The physical bosons are mixing states Z 1 and Z 2 with a mixing angle, which cause deviations from mixing states Z 1 and Z 2 with a mixing angle, which cause deviations from the SM (Z-pole parameters, shifts in the W couplings, shifts in the Weak the SM (Z-pole parameters, shifts in the W couplings, shifts in the Weak Charge, F-B Asymmetries, etc.) Charge, F-B Asymmetries, etc.) The M Z is not constrained by the theory. It can be anywhere between The M Z is not constrained by the theory. It can be anywhere between Eweak < M Z < E GUT. Eweak < M Z < E GUT.

5 II LAWHEP São Miguel das Missões, Dec Z Boson Basics: Experimental Facts In hadron colliders, the sensitivity to Z production decaying into In hadron colliders, the sensitivity to Z production decaying into quarks pairs is reduced compared to lepton pairs due to the QCD quarks pairs is reduced compared to lepton pairs due to the QCD background background 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 possible A 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 at Present limits from direct production at Tevatron and virtual effects at LEP through mixing with the Z boson, imply that M Z ~ TeV and S ~ 10. LEP through mixing with the Z boson, imply that M Z ~ TeV and S ~ 10. An observation of a Z would serve as a calibration point for future An observation of a Z would serve as a calibration point for future detectors detectors -3

6 II LAWHEP São Miguel das Missões, Dec ¿What is 331? F. Pisano and V. Pleitez, Phys. Rev. D46, (1992) 410 P.H. Frampton, Phys. Rev. Lett. 69 (1992) 2889 q L : (3, 3, Xq ) l L : (1, 3, Xl ) q L : (3, 3, Xq ) l L : (1, 3, Xl ) SM SM q L : (3, 2, 1/6) l L : (1, 2, -1/2) L = L = q R : (3, 1, 2/3) l R : (1, 1, -1) R = R = L = L = q R : (3, 1, X q ) l R : (1, 1, Xl) R = R = L = L = * * * * * * *

7 II LAWHEP São Miguel das Missões, Dec ¿Why 331? From cancelation of Chiral Anomalies and asymptotic freedom, the From cancelation of Chiral Anomalies and asymptotic freedom, the number of families should be 3 number of families should be 3 The third family is different from the two first, which could explain The third family is different from the two first, which could explain 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 of EM. Predict the quantization of electric charge and the vector nature of EM. Contains a natural Peccei-Quinn symmetry Contains a natural Peccei-Quinn symmetry New types of matter relevant at LHC New types of matter relevant at LHC

8 II LAWHEP São Miguel das Missões, Dec Fermion Structure (3 flias.) If = -1/ 3: Q E = 0 E L = ( R ) c

9 Neutral II LAWHEP São Miguel das Missões, Dec. 2007

10 II LAWHEP São Miguel das Missões, Dec Neutral Currents

11 II LAWHEP São Miguel das Missões, Dec Cross section for pp Z f f f q/A : PDFs, Z : Total Z width Z : Total Z width s : C.M Energy g v,a : Z couplings y : rapidity p z : long. momentum E: total energy Scattering angle Scattering angle M = M ff : invariant mass x A,B : momentum fractions K(M) : QED and QCD corrections Z at Tevatron

12 II LAWHEP São Miguel das Missões, Dec Z at Tevatron At NWA aproximation: ( Z /M Z ) << 1 2 Total Z production cross section Branching ratio 331 model with = -1/ 3 : z / Mz ) ~ 4 x 10 z / Mz ) ~ 4 x

13 II LAWHEP São Miguel das Missões, Dec Z at Tevatron Kinematics 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 fb Integrated 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/c Events with invariant mass Mee > 200 GeV/c+ - 2 Central Calorimeter with pseudorapidity < 1.1 Central Calorimeter with pseudorapidity < 1.1 Plug Calorimeter with pseudorapidity 1.2 < < 3.6, Plug Calorimeter with pseudorapidity 1.2 < < 3.6, Transverse energy E T > 25 GeV. Transverse energy E T > 25 GeV.

14 II LAWHEP São Miguel das Missões, Dec Z at Tevatron M Z > 920 GeV T. Aaltonen et.al. (CDF Collaboration), Phys. Rev. Lett. 99, (2007) (CalcHep Package) Z SM Z Z Z Z Z-models 95% C.L. Bounds

15 II LAWHEP São Miguel das Missões, Dec Z at LHC Kinematics at ATLAS pp collisions at C.M. energy s = 14 TeV, pp collisions at C.M. energy s = 14 TeV, Integrated Luminosity = 100 fb Integrated 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 + - Pseudorapidity < 2.5 Pseudorapidity < 2.5 Transverse energy E T > 20 GeV.Transverse energy E T > 20 GeV.

16 Z at LHC for Mz = 1500 GeV N = L

17 Z at LHC LHC Projections for 1 TeV < MZ < 5 TeV N = L Z 331 Z LR Z Z SM bkg Z

18 Conclusions For 331 model with = -1/ 3, we get the limit Mz 331 > 920 GeV at For 331 model with = -1/ 3, we get the limit Mz 331 > 920 GeV at 95% C.L in Tevatron 95% C.L in Tevatron For Mz = 1500 GeV, we get about 800 events for each 20 GeV of For Mz = 1500 GeV, we get about 800 events for each 20 GeV of energy with L = 100 fb at LHC energy with L = 100 fb at LHC At Mz = 1 TeV we found ~ events with low expected SM bcg At Mz = 1 TeV we found ~ events with low expected SM bcg The model pull the LHC dicovery potential up to 5 TeV, with 1 event The model pull the LHC dicovery potential up to 5 TeV, with 1 event

19 Prospects Calculations for other 331 models and other Mz limits Calculations for other 331 models and other Mz limits Effects of exotic decay modes as fermions, charged heavy Effects 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 ILC Extension to ILC

20 Back silides

21 II LAWHEP São Miguel das Missões, Dec Scalar Structure (3 tripletes)

22 8 Gauge Bosons1 Gauge Boson II LAWHEP São Miguel das Missões, Dec Vector Structure (9 campos)

23 NeutralCharged II LAWHEP São Miguel das Missões, Dec. 2007


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