Search for the 2nd KK statesof the mUED model

at the LHC

Kang Young LeeKonkuk U.

Seoul

YongPyong 2012@ Greenpia, Yong Pyong 2012. 2. 20-23

Based on

Sanghyeon Chang, Kang Young Lee, Jeonghyeon Song

• Phys. Lett. B708, 144 (2012).

• Phys. Rev. D, to appear

• In preparation

Outlines

• Introduction

• mUED model

• Search for the 2nd KK Higgs bosons

• Search for the 2nd KK W boson

• Search for the 2nd KK Gluon (preliminary)

• Summary

Introduction : mUED at the LHC

• The phenomenology of the mUED model is definitely fixed with only one model parameter, 1/R.

• The 2nd KK states are comparable to (or better than?) the 1st KK states to be studied at colliders.

• Only the 2nd KK CP-odd Higgs can be found at the LHC.

• The 2nd KK W boson is a good candidate to be found at the early LHC.

• The ttbar resonance can give a (first) direct bound on the mUED at the Tevatron via the 2nd KK gluon.

The universal extra dimension model (UED)

Virtues and drawbacks

The first vs. the second KK states

• m(2) ~ 2 m(1) (m(n) ~ )

• The first KK states are KK parity-odd, while the second KK states are KK parity-even.

• The first KK states are produced in pairs, while the second

KK states are singly produced due to the KK parity.

• The first KK states decay into the LKP + soft SM particles.

• The second KK states can decay into SM particles via loops.

• Comparable masses, less productions (loops), better detections (resonances).

20

2)/( mRn

KK expansions

Particle Spectra

1/R = 500 GeV, mh = 120 GeV, ΛR = 20

Search for the 2nd KK Higgs bosons

Higgs masses

where

Top quark masses

where

diagonalized by

In 4D, the effective lagrangian is given by

CP-odd KK state is produced via gluon fusion,while CP-even state canNOT.

The peak is very sharpcompared with the SM Higgs.

Productions

Assuming ∫L~ 100 fb-1,

about 10,000 will be

produced

for 1/R = 400 GeV.

About hundred events of

are expected.

Background study

Irreducible background is small. (e.g. )

Reducible background is huge from QCD events. ( of order mb)

Search for the 2nd KK W boson

W(2) masses

where

Direct production

indirect production

pp → W’ → eν / μν at the early LHC

Selection criteria

ET > 30 GeV

Isolation radius

CMS collab., PLB 698, 20 (2011)

MT distribution

Soft SM particles

We expect that the

direct bound of the

mUED will be obtained

from the search for the

W’ boson at the early

LHC.

Soft SM particles

It is difficult to probe

the mUED through this

channel at the

Tevatron.

Search for the 2nd KK Gluon (preliminary)

pp → G(2) → ttbar (resonance)

Summary

• The loop-induced decays of the 2nd KK states can be substantial in the mUED model.

• The CP-odd 2nd neutral KK Higgs can be observed at the LHC in the future.

• The 2nd KK W bosons will provide a direct bound on the mUED model at the early LHC (2012?).

• The 2nd KK gluon provide a direct bound on the mUED model at the Tevatron through the resonant ttbar channel when Λ=50/R.

t1 – t2 mixing angle