introduction to universal extra dimensions (ueds)

Introduction to Introduction to universal extra dimensions (UEDs) universal extra dimensions (UEDs)

Mitsuru Kakizaki (ICRR, University of Tokyo)May 10, 2005 @ KEK

Refs: Original idea: Appelquist, Cheng, Dobrescu, PRD67 (2000) 035002 Second KK particle physics: MK, Matsumoto, Sato, Senami, hep-ph/0502059 UED vs SUSY at CLIC: Battaglia, Datta, De Roeck, Kong, Matchev, hep-ph/0502041

Pedagogical introduction to UED models Comparison of UED and SUSY phenomenology

Pedagogical introduction to UED models Comparison of UED and SUSY phenomenology

UED cosmology and astrophysics Dr. Matsumoto’s talk

Probing extra dimensions at linear colliders Prof. Raychaudhuri’s talk

May 10, 2005 Mitsuru Kakizaki 2

Large extra dimensionsWarped extra dimensions

Today’s topic

[Arkani-hamed, Dimopoulos, Dvali PLB 429 (1998) 263][Randall, Sundrum PRL 83 (1999) 3370]

1. Motivation1. Motivation

etc.

Extra-dimension scenarios provide new views of various problemsExtra-dimension scenarios provide new views of various problems

Hierarchy problem:

Fermion mass hierarchy Existence of dark matter

[Arkani-hamed, Schmaltz PRD 61 (2000)]

Universal extra dimensions (UEDs) [Appelquist, Cheng, Dobrescu, PRD67 (2000) 035002]

Universal extra dimensions (UEDs) [Appelquist, Cheng, Dobrescu, PRD67 (2000) 035002]The Lightest Kaluza-Klein particle (LKP) in UED models is an excellent candidate for dark matter due to Kaluza-Klein (KK) parity [Servant, Tait, NPB 650 (2003) 391]


Study at linear colliders is mandatoryStudy at linear colliders is mandatory

UEDSUSY

R parity stabilizes the LSP

Kinematics of 1st KK modes resembles that of superparticles with degenerate mass

KK parity stabilizes the LKP

Attention to spins of new particles and second KK modes

Superparticle mass 1st KK mode mass

UED is similar to SUSYUED is similar to SUSY

SUSY breaking mass

SMSM

SUSY Same spin

Different spin


ContentsContents

1. Motivation2. Universal extra dimensions (UEDs)3. UED vs SUSY4. Summary


2. Universal extra dimensions2. Universal extra dimensions

For definiteness, we concentrate on one-extra dimensional cases in this talk

Idea: All SM particles propagate compact spatial extra dimensionsIdea: All SM particles propagate compact spatial extra dimensions

[Appelquist, Cheng, Dobrescu, PRD67 (2000) 035002]

Dispersion relation: Momentum along the extra dimension Mass in four-dimensional viewpoint

For compactification with radius ,

Mass spectrum for

is quantized

Momentum conservation in the extra dimensionConservation of KK number in each vertex


Parameters in UED modelsParameters in UED models

c.f. minimal SUGRA:

: Cutoff scale: Size of extra dimension : Higgs boson mass

Kaluza-Klein expansion (Fourier expansion):

Parameters in UED models are completely specified in terms of the SM parametersParameters in UED models are completely specified in terms of the SM parameters

and

Only three free parameters in minimal UED model:

Zero modes are identified with SM fields


Minimal UEDMinimal UED

Conservation of KK parity [+ (--) for even (odd) ]The lightest KK particle (LKP) is stable

c.f. R-parity and the LSP in SUSY models

Reflection sym. under

Experimental limit on is weaker than other extra-dimensional models:

Electroweak precision tests

Single KK particle cannot be produced{ Dark matter

In 5D spacetime, spinor representation has 4 complex components

Chiral fermions in 4D e.g.

DiracDiracChiral


Particle contents in minimal Particle contents in minimal UEDUED

Electroweak symmetry breaking effects are suppressed for higher KK modesThere appear infinite towers of KK modes

with quantum numbers identical to SM particlesThere appear infinite towers of KK modes with quantum numbers identical to SM particles

KK level

New particles:

MasslessMassive

Massive(Mass )

Dirac

Gauge boson Fermion (SU(2)L)

Real scalar

Scalar (SU(2)L)

SM particles:(Mass )

DiracChiral

Complex scalar


Interactions in UED modelsInteractions in UED models e.g. gauge interaction of fermion:

KK expansion

5D

Couplings in UED models are determined by corresponding SM onesCouplings in UED models are determined by corresponding SM ones

4DFor

SM

KK


Compactification 5-dimensional Lorentz invariance Orbifolding translational invariance in the 5th dimension Radiative corrections generate KK mass splitting

Compactification 5-dimensional Lorentz invariance Orbifolding translational invariance in the 5th dimension Radiative corrections generate KK mass splitting

Radiative corrections to Radiative corrections to mass spectra of KK modesmass spectra of KK modes

[Cheng, Matchev, Schmaltz, PRD66, 036005 (2002)]

One-loop corrected masses of 1st KK modes

c.f. SUSY: Universal soft mass at cutoff scale Mass splitting at weak scale

Tree level masses spectrum of 1st KK modes


LHC:[Cheng, Matchev, Schmaltz PRD 66 (2002) 056006]

Signals of 1st KK modes are similar to those of superparticles

Discovery reach for minimal UED:

3. UED vs SUSY3. UED vs SUSY

Future colliders is promising for distinguishing UED and SUSY

(UED is called “Bosonic supersymmetry”)

Observation of effects caused by second KK modes Determination of spins of new particles


Contrasting SUSY and UED at CLICContrasting SUSY and UED at CLIC (Multi-TeV collid (Multi-TeV collider)er)

[Battaglia, Datta, De Roeck, Kong, Matchev, hep-ph/0502041]

missing energy > 2.5 TeV transverse energy < 150 GeV event sphericity > 0.05 missing trans. energy > 50 GeV

Event seletion: SM background:

(small polar angle)

MSSM parameters are adjusted to reproduce UED kinematics

Comparison of

with in UED

in SUSY

UED parameters:

Missing

Rad. cor.


Angular distribution Angular distribution and spin measurements and spin measurements

: Spin 1/2

: Spin 0

: signal + background: signal

UED:

SUSY:at

Factor

[From Battaglia, Datta, De Roeck, Kong, Matchev, hep-ph/0502041]


Discrimination of UED from Discrimination of UED from SUSYSUSY Cross section for

resonanceIncludingbeamstrahlung

Photon energy spectrum in

c.f. SUSY: at threshold region, no sharp peak due to resonance



4. Summary4. Summary

LHC would not distinguish UED from SUSY models

Study at linear colliders is mandatory

Attention to Spins of new particles Effects caused by second KK particles

Attention to Spins of new particles Effects caused by second KK particles

Remarkable features of UED models:

Towers of KK modes with spins identical to corresponding SM particlesSmall number of free parametersExcellent dark matter candidate: LKP


Backup slidesBackup slides


Collider signatures at LHCCollider signatures at LHC

The discovery reach: Signals of 1st KK modes are similar to those of superparticles

The discovery reach: Signals of 1st KK modes are similar to those of superparticles

[Cheng, Matchev, Schmaltz PRD66 (2002) 056006]

Discovery reachDecay chains of 1st KK modes


One-loop corrected massesOne-loop corrected masses of 1st KK modes of 1st KK modes

[From Cheng, Matchev, Schmaltz PRD66 (2002) 056006]


Muon energy spectrumMuon energy spectrum



Threshold scanThreshold scan Cross section for



Radiative return toRadiative return to


Photon energy spectrum in


Radiative corrections KK number violating couplings

pair production is naturally enhanced by -resonance in the s-channel

Second KK particle physicsSecond KK particle physics

Signal of 2 lepton + large missing energy is expected to have large cross section and be almost background freeSignal of 2 lepton + large missing energy is expected to have large cross section and be almost background free

(2nd KK mode mass)(1st KK mode mass)

[MK, Matsumoto, Sato, Senami, hep-ph/0502059]

e.g.


Threshold Threshold singularitysingularity

Threshold cross section for KK quarkonium at linear collider

Precise determination of parameters is possible Precise determination of parameters is possible

[MK, Matsumoto, Okada, Yamashita, …]

KK quarkonium

KK quarkonium cross section for small decay width

Energy of bound state:

introduction to universal extra dimensions (ueds)

Documents

extra dimension mass

ued models comparison

kk expansioncouplings

degenerate mass kk parity

kk modes superparticle

probing extra dimensions

kk particle physics

ued modelsc