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Z1 production via Vector Boson Fusion at the LHC in the four-site Higgsless Model

Z1 production via Vector Boson Fusion at the LHC in the four-site Higgsless Model. Andrew Stump University of Rochester Pheno 2012 5-7-2012. Deconstructed Higgsless Models. In Higgsless Models, Electroweak Symmetry Breaking occurs through boundary conditions on 5 dimensional gauge fields.

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Z1 production via Vector Boson Fusion at the LHC in the four-site Higgsless Model

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  1. Z1 production via Vector Boson Fusion at the LHC in the four-site Higgsless Model Andrew Stump University of Rochester Pheno 2012 5-7-2012

  2. Deconstructed Higgsless Models • In Higgsless Models, Electroweak Symmetry Breaking occurs through boundary conditions on 5 dimensional gauge fields. • Lead to extra copies of gauge fields • Theories with discrete 5th dimension called Deconstructed, can cut off KK towers in gauge invariant way • Effective theories, so can include possible scalars in UV completion • Use Moose Diagrams Σ1 Σ2 … GL GR G1 G2

  3. Four-Site Model • Gi is group with transformation Ui • Non-linear sigma fields (Σi) come from 5th dimension gauge field component • Σi fields transform according to Σi→ Ui-1ΣiUi† • Unitary gauge (Σi→ 1) leads to copies of W, Z bosons • Two new sets of bosons, W±1,2 and Z1,2 in the 350 GeV to few TeV range • Unitarity violation delayed to about 5 TeV Σ1 Σ3 Σ2 SU(2)L U(1) SU(2)1 SU(2)2

  4. Four-Site Gauge Lagrangian • Similar to SM but with extra terms for inner groups and sigma fields • Here f1, f2, f3are link coupling constants [Energy]. They parameterize distances in the extra dimension (we set f1= f3 ). • No Higgs!

  5. Four-Site Fermion Lagrangian • Inner gauge couplings set equal • The biparametrize couplings to new gauge fields/movement in new dimensions: . • Here:

  6. Model Parameters • Starting parameters are f1 , f2 , , , and b1,b2 • SM parameters (e, Gf, etc.) depend on the new parameters • Set SM parameters to their measured values partially constrains new parameters • Left with two new boson mass scales (M1/M2 = z) and fermion couplings

  7. Z1 Production • The new gauge bosons are produced through quark and SM gauge boson couplings • Drell-Yan production has been calculated (Accomando, De Curtis, Dominici, and Fedeli), and is assumed to be the dominant mode. • Vector Boson Fusion suppressed from propagators, couplings and phase space Drell-Yan Gauge Boson Fusion

  8. Couplings

  9. Drell Yan Z1 production at 7 TeV LHC

  10. Vector Boson Fusion (7 TeV LHC) • Preliminary • Higher cross section than DY

  11. Conclusions • Higgsless Models break EWS without a physical Higgs • Gauge Boson Fusion ends up being competitive with Drell-Yan • Dominant decays of Z1 are to W bosons when available • Signals could be seen or ruled out at the LHC soon

  12. Extra Slides

  13. Feynman Rules • Coupling to fermions • Tri-gauge boson coupling

  14. Drell-Yan Z1 production (14TeV LHC)

  15. Decays • Because of the weak boson copy structure, signatures can be similar to SM, but Z1/Z2 decay preferentially to bosons. • Widths can be from a few GeV to hundreds • Z2 to WW and W1W1 highly suppressed (Widths to W’s from Accomando, De Curtis, Dominici and Fedeli - Phys. Rev. D 83, 015012 (2011))

  16. Gauge Boson Trilinear Couplings (1) Accomando, De Curtis, Dominici, Fedeli, hep-ph/1010.0171v1

  17. Gauge Boson Trilinear Couplings (2) Accomando, De Curtis, Dominici, Fedeli, hep-ph/1010.0171v1

  18. Gauge Boson Trilinear Couplings (3) Accomando, De Curtis, Dominici, Fedeli, hep-ph/1010.0171v1

  19. Covariant Derivatives

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