# Presentation: 209203

## New Ideas in Randall-Sundrum Phenomenology

- José Santiago
- Fermilab

## Randall-Sundrum 101

- RS offers a nice solution to the hierarchy problem

## Randall-Sundrum 101

- RS offers a nice solution to the hierarchy problem

## Randall-Sundrum 101

- Fermions (and gauge bosons) in the bulk
- nice flavor theory: hierarchical masses + FCNC
- Higher-dimensional operators suppressed

## Randall-Sundrum 101

- Fermions (and gauge bosons) in the bulk
- nice flavor theory: hierarchical masses + FCNC
- Higher-dimensional operators suppressed
- Fermion localization from bulk mass

- zero mode

- zero mode

- Agashe, Servant JCAP (05)

- It is also possible to use different b.c.

- KK modes might be light

## Randall-Sundrum faces reality

- Gauge boson KK modes localized towards IR brane

- Large mixing with the Z and W zero modes through the Higgs

- Large T parameter

## Randall-Sundrum faces reality

- Top (bottom) zero modes localized towards IR brane

- Large gauge and Yukawa couplings to GB and fermion KK modes

- Large anomalous Zbb coupling

## Randall-Sundrum faces reality

**Large corrections to the ****T parameter**** and the   ****Zbb coupling**** force   to be ****beyond the LHC reach**** **

- No Randall-Sundrum physics at the LHC
- The model becomes very fine-tuned

## RS needs protection: call custodial symmetry

- Custodial protection of Randall-Sundrum
- Bulk gauge symmetry:

- Agashe, Delgado, May, Sundrum JHEP (03)

## RS needs protection: call custodial symmetry

- Custodial protection of Randall-Sundrum
- Bulk gauge symmetry:

- Agashe, Contino, Da Rold, Pomarol PLB (06)

- Symmetry broken by b.c. to                             on the UV

## Fermion Quantum Numbers

- The simplest option is bidoublets under

- The Higgs is also a bidoublet with

## Calculable corrections to T and Zbb

- T and Zbb protected (at tree level) by custodial symmetry broken on the UV brane:
- Quantum corrections are calculable (finite)
- T and Zbb are insensitive to physics above
- One loop corrections are important
- Bidoublets contribute negative to T
- Singlets contribute positive to T
- Large positive T leads to large positive

- Carena, Pontón, J.S., Wagner NPB (06)

## Calculable corrections to T and Zbb

- UV         singlet localization         IR

- T negative in most of parameter space:  the RH top is almost flat (LH top/bottom near IR)

## Calculable corrections to T and Zbb

- UV         singlet localization         IR

- T negative in most of parameter space:  the RH top is almost flat (LH top/bottom near IR)

- Positive T leads to large deviations in Zbb

## Gobal Fit to Electroweak Observables

- We have performed a global fit to all EW observables including:
- All tree-level effects at leading order in
- Leading one loop effects on: T, Zbb and S
- We compute the     as a function of the localization parameter of the fermions                                        and
- To reduce number of parameters we optimize with respect to

- Carena, Pontón, J.S., Wagner hep-ph/0701055
- Han, Skiba PRD (05-06)

## Gobal Fit to Electroweak Observables

- IR         light localization         UV

## Gobal Fit to Electroweak Observables

- New measurements of     and       generate a tension in the SM
- The contribution in our model goes in the right direction

**PRELIMINARY**

## Fermion Spectrum

- First two generation KK modes

- Not a necessary prediction

## Fermion Spectrum

- First two generation KK modes

- Not a necessary prediction

## Fermion Spectrum

- First two generation KK modes

- Not a necessary prediction

## Fermion Spectrum

- Solid prediction

## Fermion Spectrum

- Solid prediction

## Fermion Spectrum

- Solid prediction

## Collider Phenomenology

- Tevatron
- Searches for new quarks
- Interesting possibilities for Higgs physics
- LHC
- GB KK modes discovery up to ~5 TeV
- Exotic decay channels
- t’ discovery up to ~1 TeV
- Exciting Higgs physics

## Tevatron searches

- New quark searches

## Tevatron searches

- Higgs physics

- Top mixing with KK modes        reduced top Yukawa

## Tevatron searches

- Higgs physics

- But new production mechanism mediated by q’

## Tevatron searches

- LS dileptons: SUSY vs q’ (MH=170 GeV)

- D0 Note 5126-CONF (1fb-1)

## Tevatron searches

- LS dileptons: SUSY vs q’ (MH=170 GeV)

- D0 Note 5126-CONF (1fb-1)

**PRELIMINARY**

- Simulations using MG/ME+Pythia+PGS4

## Tevatron searches

- LS dileptons: SUSY vs q’ (MH=170 GeV)

- D0 Note 5126-CONF (1fb-1)

- Alternative cuts: signal is harder than backgrounds

**PRELIMINARY**

## Tevatron searches

- LS dileptons: SUSY vs q’ (MH=170 GeV)

- D0 Note 5126-CONF (1fb-1)

- Alternative cuts: signal is harder than backgrounds

**PRELIMINARY**

## Tevatron searches

- LS dileptons: SUSY vs q’ (MH=170 GeV)

- D0 Note 5126-CONF (1fb-1)

- Result of the analysis for 1 fb-1

- Main backgrounds considered

- Our signal, assuming improved analysis is 2.5 events per fb-1

- In the absence of signal ~2 fb-1 could set a 95% C.L. bound

## LHC searches

-              accessible at the LHC in Drell-Yan up to
- KK gluons require careful treatment of *top jets *and improved fake jet efficiencies but
- Exotic decay channels with 4 or more W’s may allow early discovery of q’ with Mq’=500 GeV with 10 fb-1
- t’ with masses             can be discovered at the LHC

- Ledroit, Moreau, Morel ph/0703262

- Agashe, Belyaev, Krupovnickas, Perez, Virzi  ph/0612015
- Lillie, Randall, Wang ph/0701166

- Dennis, Ünel, Servant, Tseng ph/0701158

## LHC Higgs physics

- Gluon fusion production reduced up to a factor 0.65
-            slightly enhanced (up to 1.12 for light Higgs)

## LHC Higgs physics

- Gluon fusion production reduced up to a factor 0.65
-            slightly enhanced (up to 1.12 for light Higgs)
- But new production mechanism mediated by q’

## LHC Higgs physics

- Gluon fusion production reduced up to a factor 0.65
-            slightly enhanced (up to 1.12 for light Higgs)
- But new production mechanism mediated by q’
- New possibilities for early discovery
- 5σ discovery for mT=500 GeV and mH=115 GeV with 8 fb-1
- T is a vector-like singlet

- Aguilar-Saavedra JHEP (06)

- But need dedicated analysis!

## Conclusions

- Custodial protection of T and Zbb: new opportunities for Randall-Sundrum models
- Quantum corrections calculable and relevant:
- Fix some features of the model (       near IR brane)
- Help ease the tension after new Mtop, MW measurements
- Very rich,interesting and new phenomenology
- Light (                ) gauge boson KK modes
- Light (                  ) quarks, some with exotic charges
- Spectacular signatures: multigauge bosons, LS leptons, ...
- Important effects in Higgs physics

## Slide 38

## Backup slides

## Observables used in the global fit

- Bottom considered independently

## Custodial protection of Zbb

- Fermion coupling to Z at zero momentum
-      can be protected by a subgroup of the custodial symmetry

## A model of gauge-Higgs unification

- Bulk gauge symmetry                   broken to                     	             on the IR and to the SM on the UV
- A5 along                has a zero mode with the Higgs quantum numbers exponentially localized towards the IR brane
- Calculable Higgs potential
- Solution to the little hierarchy problem
- Yukawa couplings through gauge couplings: fermion masses and mixings from non-trivial b.c.
- Bidoublet embedding:

- Contino, Nomura, Pomarol NPB (03)
- Agashe, Contino, Da Rold, Pomarol (05-06)