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Phenomenology of Warped Models with Custodial Symmetry

Explore the motivations and expectations of studying warped models with custodial symmetry, focusing on the bosonic and fermionic spectra, model details, low energy effects, and decay channels. Discuss implications for Higgs physics, fermion discovery, and vector boson detection. References key studies by Agashe, Delgado, Carena, and others.

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Phenomenology of Warped Models with Custodial Symmetry

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  1. Phenomenology of Warped Models with Custodial Symmetry José Santiago Fermilab Budapest, June 27, 2007

  2. Outline • Motivation (... hope you were at Eduardo’s talk!) • What to expect: • Bosonic spectrum • Fermionic spectrum • Capturing the essentials: SM + vector-like quarks • The model: Bidoublets and singlets • Low energy effects and decay channels • Phenomenological implications: • Fermion discovery • Implications for Higgs physics • Vector boson discovery • Conclusions

  3. Motivation • Warped models with custodial symmetry: • Natural theory of EWSB • Compelling theory of flavor • Realistic models (custodial protection of Zbb) have very characteristic spectrum • Randall-Sundrum phenomenology revisited: • New vector-like fermions • Discovery of the fingerprints of custodial protection • Implications for Higgs physics • Implications for discovery of vector resonances Agashe, Delgado, May, Sundrum JHEP (03) Agashe, Contino, Da Rold, Pomarol PLB (06)

  4. What to expect? • Bosonic spectrum • Tower of bosonic resonances • Fermionic spectrum • Naturalness (cancellation of top loops) and custodial protection of Zbb predict light quarks with well defined quantum numbers that mix strongly with third generation quarks Carena, Pontón, J.S., Wagner NPB(06) + hep-ph/0701055

  5. What to expect? • Bosonic spectrum • Tower of bosonic resonances • Fermionic spectrum • Naturalness (cancellation of top loops) and custodial protection of Zbb predict light quarks with well defined quantum numbers that mix strongly with third generation quarks

  6. Capturing the essentials • Extend the SM with the relevant vector-like quarks • With mass matrix (assume no mixing to b)

  7. Capturing the essentials • Extend the SM with the relevant vector-like quarks • With mass matrix (assume no mixing to b)

  8. Capturing the essentials • Extend the SM with the relevant vector-like quarks • With mass matrix (assume no mixing to b)

  9. Low Energy Effects • Top (bottom) couplings

  10. Low Energy Effects Particular (but well motivated) limit: degenerate bidoublet and heavy singlet • Top (bottom) couplings Suppressed low energy effects!!

  11. Main Decay Channels • Singlet • Non-degenerate bidoublet • Charge 2/3 • Charges 5/3 and -1/3

  12. Main Decay Channels • Singlet • Non-degenerate bidoublet • Charge 2/3 • Charges 5/3 and -1/3

  13. Phenomenological implications (I) • Vector-like quark discovery • T has been extensively studied (recently in LH models) • Bidoublets have been less studied (but are far more interesting!) • Exotic decay channels • Large BR of charge 2/3 into Z Dennis, Ünel, Servant, Tseng ‘07

  14. Phenomenological implications (II) • Implications for Higgs physics • Top Yukawa reduced due to mixing • Reduction of gluon fusion Higgs production • Small enhancement of (not enough to compensate for the decrease in gluon fusion) Recall vector-like quark masses (mostly) not from EWSB small contribution to gluon fusion

  15. Phenomenological implications (II) • Implications for Higgs physics • But new (strong) production mechanisms through decay of vector-like quarks (with large BR into Higgs)

  16. Phenomenological implications (II) • Implications for Higgs physics • But new (strong) production mechanisms through decay of vector-like quarks (with large BR into Higgs) Aguilar-Saavedra JHEP (06) • 8 fb-1 can allow for a 5σ Higgs discovery for mH=115 GeV and a vector-like singlet T with MT=500 GeV • Better prospects for bidoublets!

  17. Phenomenological implications (III) • Discovery of KK gluons • Studies done assuming gluons decay only to (RH) tops • Very hard tops, pT~TeV, difficult to reconstruct (top jets) • Realistic models have a richer structure (new decay channels open) • Not all tops come directly from the KK gluon (can miss peak) • New decays produce softer tops (easier to reconstruct) • If light bidoublets: large number of fermions with strong coupling to KK gluons very wide resonance (BKTs probably necessary) Agashe, Belyaev, Krupovnickas, Perez, Virzi ph/0612015 Lillie, Randall, Wang ph/0701166 Lillie, Su, Tait, to appear

  18. Phenomenological implications (III) • Discovery of KK gluons

  19. Phenomenological implications (III) • Discovery of KK gluons

  20. Phenomenological implications (III) • Discovery of KK gluons

  21. Conclusions • Realistic models with warped extra dimensions have a very rich fermionic spectrum • SM+ vector-like quarks captures the main features • Time to revisit RS phenomenology • New fermions as fingerprints of custodial symmetry • Implications for Higgs physics • Implications for the discovery of bosonic resonances

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