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The Search for Z* and Excited Bosons in High-Energy Physics

Explore the dynamics, interactions, and theoretical motivations behind the search for excited fermions, chiral bosons like Z*, and other heavy particles in particle physics experiments at LEP, HERA, Tevatron, and the Large Hadron Collider. Theoretical comparisons between Z' and Z*, implications for the Higgs mass hierarchy problem, and model-independent predictions for excitations like W* and Z* are discussed. Discover the significance of invariant mass, transverse momentum, angular distributions, and unique signatures in the hunt for new physics beyond the Standard Model.

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The Search for Z* and Excited Bosons in High-Energy Physics

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  1. Heavy Excited Bosons keywords: Z-prime, Z-star W-prime,W-star M.V. Chizhov (JINR and Sofia University)

  2. Excited particles (compositeness) Searches for excited fermions y*have been performed at LEP, HERA and the Tevatron, and are also continuing by the CMS and ATLAS experiments at the LHC. y* why not Z* ? M. C., V. A. Bednyakov, and J. A. Budagov, Proposal for chiral bosons search at LHC via their unique new signature, Phys. Atom. Nucl. 71 (2008) 2096; arXiv:0801.4235 Z* has differentinteractions than Z’!

  3. Low energy searches • Muon decay → е  е • Radiative pion decay → е е • Neutron decayn→p е е • Kaon decay K → е е • Lepton anomalous magnetic moment • …

  4. Large Hadron Collider or future colliders

  5. Naturalness of the Higgs mass Mr(s). X EW scale—1 Mr. Higgs GUT scale—1 and A. Hoecker

  6. Motivation for SM extension The main theoretical motivation for beyond the StandardModel physics around TeV energies (LHC) is provided by the Hierarchy Problem, an inexplicable the UltraVioletstability of the weak interaction scale (MW,Z = 102 GeV)versus the Planck mass (MP = 1019 GeV), WHY IS M2W,Z/M2P = 10-34 ? Introduction of new spin-1 bosons with the internal quantum numbers identical to the Standard Model Higgs doubletcan help to solve by the Hierarchy Problem. MW,Z MW*,Z* MP M. Chizhov and G. Dvali “Origin and Phenomenology of Weak-Doublet Spin-1 Bosons”, Phys. Lett. B 703 (2011) 593, arXiv:0908.0924 102 GeV 103 GeV 1019 GeV

  7. Standard ModelSU(2)LU(1) Y M.V. Chizhov, Mod. Phys. Lett. A8 (1993) 2753 M.V. Chizhov, G. Dvali, Origin and Phenomenology of Weak-Doublet Spin-1 Bosons, Phys. Lett. B703 (2011) 593

  8. We predict an existence of new excited chiral particles W* and Z* with new unique properties. ATLAS is already looking for them!

  9. k k k j j j Difference b/w Z’ and Z* couplings and R R Z* L L L R L R Z’ L R L R

  10. Theoretical comparision between Z’andZ* invariant mass transverse momentum M. Chizhov, Disentangling between Z’ and Z* with first LHC data, arXiv:0807.5087 angular distribution pseudorapidity difference

  11. Z’ and graviton angular distributions incomplete!

  12. Jacobian factor for cosθ→pT Z’ Z* “The divergence at q = p/2 which is the upper endpoint pTM/2 of the pT distribution stem from the Jacobian factor and is known as a Jacobian peak ; it is characteristic ofalltwo-body decays…” V. Barger “Collider physics” w r o n g !

  13. ATLAS search for a heavy gauge boson decaying to a charged lepton and a neutrino in 4.7 fb-1 of pp collisions at sqrt(s)= 7 TeV ATLAS-CONF-2012-086

  14. Invariant dilepton mass distributions Several models predict new high mass neutral resonances that could decay into dilepton pairs(Z’, G*, TC, KK, …) Z Z’ Z* MZ

  15. M

  16. Δη ≡|η1-η2|distribution M.Chizhov, V. Bednyakov, J.Budagov, Phys. Atom. Nuclei 75 (2012) 90; arXiv: 1106.4161 [hep-ph] =/2 =/4 The excited bosons have a unique model independent  distribution. p p p p QCD Spin 2 Z* (excited spin 1) Spin 0 h ,Z’ ,G* , … Z* Spin 1  =|1-2 |

  17. Δη< 1 cut for DY M.Chizhov, V. Bednyakov, J.Budagov, arXiv:1109.6876v1 [hep-ph] Effectively leads to 20 – 30% of increase of statistics

  18. Proposed list for Snowmass study pp → Z*/W* and ee → Z*/W* production with the following decays: Dilepton channel: Z* →ll, W* → ln (l = e, m, t) Dijet channel: Z*/W* → qq Single top channel: W* → tb Top pair channel: Z* → tt

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